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Sato H, Sugimoto T. Direct Operando Identification of Reactive Electron Species Driving Photocatalytic Hydrogen Evolution on Metal-Loaded Oxides. J Am Chem Soc 2024. [PMID: 39189394 DOI: 10.1021/jacs.3c14558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
Performing operando spectroscopy under practical reaction conditions and extracting spectral components correlating with reaction activity are crucial in elucidating the reactive species in photocatalysis. However, the observation of weak signals corresponding to reactive photogenerated species is frequently hampered under reaction conditions owing to intense background signals originating from thermally induced species unrelated to the photoinduced reactions. Herein, by synchronizing the millisecond periodic excitations of photocatalysts with a Michelson interferometer used for FT-IR spectroscopy, we succeeded in significantly suppressing the signals derived from thermally excited electrons and observing the reactive photogenerated electrons contributing to the photocatalytic hydrogen evolution. This demonstration was achieved for metal-loaded oxide photocatalysts under steam methane reforming and water splitting conditions. Although it has long been conventionally believed that loaded metal cocatalysts function as sinks for reactive photogenerated electrons and active sites for reduction reactions, we found that the free electrons in the metal cocatalysts were not directly involved in the reduction reaction. Alternatively, the electrons shallowly trapped in the in-gap states of oxides contributed to enhancing the hydrogen evolution rate upon the loading of metal cocatalysts. We verified that the electron abundance in the in-gap states was clearly correlated to the reaction activity, suggesting that metal-induced semiconductor surface states formed in the periphery of the metal cocatalyst play key roles in the photocatalytic hydrogen evolution. Our microscopic insights shift a paradigm on the traditionally believed role of metal cocatalysts in photocatalysis and provide a fundamental basis for rational design of the metal/oxide interfaces as promising platforms for nonthermal hydrogen evolution.
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Affiliation(s)
- Hiromasa Sato
- Department of Materials Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
| | - Toshiki Sugimoto
- Department of Materials Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Okazaki, Aichi 444-8585, Japan
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2
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Liu C, Wang C, Wang R, Li D, Jin D, Ohtani B, Liu B, Ma H, Du J, Liu Y, Zhang X. Ultrasonic-Induced Surface Disordering Promotes Photocatalytic Hydrogen Evolution of TiO 2. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 39191507 DOI: 10.1021/acsami.4c10977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/29/2024]
Abstract
Surface disordering has been considered an effective strategy for tailoring the charge separation and surface chemistry of semiconductor photocatalysts. A simple but reliable method to create surface disordering is, therefore, urgently needed for the development of high-performance semiconductor photocatalysts and their practical applications. Herein, we report that the ultrasonic processing, which is commonly employed in the dispersion of photocatalysts, can induce the surface disordering of TiO2 and significantly promote its performance for photocatalytic hydrogen evolution. A 40 min ultrasonic treatment of TiO2 (Degussa P25) enhances the photocatalytic hydrogen production by 42.7 times, achieving a hydrogen evolution rate of 1425.4 μmol g-1 h-1 without any cocatalyst. Comprehensive structural, spectral, and electrochemical analyses reveal that the ultrasonic treatment induces the surface disordering of TiO2, and consequently reduces the density of deep electron traps, extends the separation of photogenerated charges, and facilitates the hydrogen evolution reaction relative to oxygen reduction. The ultrasonic treatment manifests a more pronounced effect on disordering the surface of anatase than rutile, agreeing well with the enhanced photocatalysis of anatase rather than rutile. This study demonstrates that ultrasonic-induced surface disordering could be an effective strategy for the activation of photocatalysts and might hold significant implications for the applications in photocatalytic hydrogen evolution, small molecule activation, and biomass conversion.
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Affiliation(s)
- Chunyao Liu
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, Changchun 130024, China
| | - Changhua Wang
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, Changchun 130024, China
| | - Rui Wang
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, Changchun 130024, China
| | - Dashuai Li
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, Changchun 130024, China
| | - Dexin Jin
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, Changchun 130024, China
| | - Bunsho Ohtani
- Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Baoshun Liu
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, No. 122, Luoshi Road, Wuhan 430070, China
| | - He Ma
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, Changchun 130024, China
| | - Jinglun Du
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, Changchun 130024, China
| | - Yichun Liu
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, Changchun 130024, China
| | - Xintong Zhang
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, Changchun 130024, China
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3
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Hyun Kim Y, Gyeong Bae Y, Yong Sohn W. Uncovering Energetic Positions of Surface Trap States in α-Fe 2O 3 Treated with Cobalt Phosphate (Co-Pi) Using Charge Carrier-Selective Heterodyne Transient Grating Technique. Chemphyschem 2024; 25:e202300894. [PMID: 38369879 DOI: 10.1002/cphc.202300894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 02/17/2024] [Accepted: 02/18/2024] [Indexed: 02/20/2024]
Abstract
Near-field heterodyne transient grating (NF-HD-TG) responses of hematite (α-Fe2O3) treated with cobalt phosphate (Co-Pi) were measured with the burn lasers inducing the depletion of the response by the removal of the trapped charge carriers in the target state, which is called charge carrier-selective heterodyne transient grating (CS-HD-TG) spectroscopic technique. We found that two distinct trap states co-existed in Co-Pi loaded on the surface of α-Fe2O3. One of them named r-SS2, of which potential was similar to that of r-SS1 in the surface of α-Fe2O3, acted as a recombination centre but could increase the lifetime of the trapped holes by the charge separation. We also revealed that the energetic position of the other (i-SS2), which has been regarded as the intermediate state for oxygen evolution reaction with low overpotential, was higher than that of i-SS1 in α-Fe2O3 but lower than those of r-SS1 and r-SS2.
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Affiliation(s)
- Young Hyun Kim
- Department of Chemistry, Chungbuk National University, Chungdae-ro 1, Cheongju, Chungbuk 28644, Korea
| | - Yu Gyeong Bae
- Department of Chemistry, Chungbuk National University, Chungdae-ro 1, Cheongju, Chungbuk 28644, Korea
| | - Woon Yong Sohn
- Department of Chemistry, Chungbuk National University, Chungdae-ro 1, Cheongju, Chungbuk 28644, Korea
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4
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Garcia‐Esparza AT, Qureshi M, Skoien D, Hersbach TJP, Sokaras D. A multimodal flow reactor for photocatalysis under atmospheric conditions. J Chem Phys 2023; 159:244201. [PMID: 38153150 PMCID: PMC10756709 DOI: 10.1063/5.0179259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 12/05/2023] [Indexed: 12/29/2023] Open
Abstract
Photocatalysis is a promising concept for the direct conversion of solar energy into fuels and chemicals. The design, experimental protocol, and performance of a multimodal and versatile flow reactor for the characterization of powdered and immobilized photocatalysts are herein presented. Ultimately, this instrument enables rigorous evaluation of photocatalysis performance metrics. The apparatus quantifies transient gas-phase reaction products via online real-time gas analyzer mass spectrometry (RTGA-MS). For H2, the most challenging gas, the photocatalytic system's RTGA-MS gas detection sensitivity spans over three orders of magnitude and can detect down to tens of parts per million under atmospheric conditions. Using Pt nanoparticles supported on anatase TiO2 photocatalyst via wet impregnation, the instrument's capability for the characterization of photocatalytic H2 evolution is demonstrated, resulting in an apparent quantum yield (AQY) of 48.1% ± 0.9% at 320 nm, 45.7% ± 0.3% at 340 nm and 31% ± 1% at 360 nm. The photodeposition of Pt on anatase TiO2 was employed to demonstrate the instrument's capability to track the transient behavior of photocatalysts, resulting in an improved 55% ± 2% AQY for H2 evolution at 340 nm from aqueous methanol. This photocatalytic instrument enables systematic study of a wide variety of photocatalytic reactions such as water splitting and CO2 reduction to valuable C2+ fuels and chemicals.
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Affiliation(s)
- Angel T. Garcia‐Esparza
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Muhammad Qureshi
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Dean Skoien
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Thomas J. P. Hersbach
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Dimosthenis Sokaras
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
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Shenoy S, Chuaicham C, Shanmugam M, Okumura T, Balijapalli U, Li W, Balakumar V, Sasaki K, Sekar K. Tailoring Interfacial Physicochemical Properties in Cu 2O-TiO 2@rGO Heterojunction: Insights from EXAFS and Electron Trap Distribution Analysis. ACS APPLIED MATERIALS & INTERFACES 2023; 15:54105-54118. [PMID: 37948059 DOI: 10.1021/acsami.3c12130] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
In this study, a solution-based synthesis technique was utilized to produce Cu2O nanoparticles (NPs) on TiO2 nanofibers (TNF), which were then subsequently coated with reduced graphene oxide (rGO) nanosheets. In the absence of any cocatalyst, CTNF@rGO-3% composite displayed an ideal photocatalytic H2 evolution rate of 96 μmol g-1 h-1 under visible light irradiation, this was 10 times higher than that of pure TNF. At 420 nm, the apparent quantum efficiency of this composite reached a maximum of 7.18%. Kelvin probe force microscopy demonstrated the formation of an interfacial electric field that was oriented from CTNF to rGO and served as the driving force for interfacial electron transfer. The successful establishment of an intimate interface between CTNF@rGO facilitated the efficient transfer of charges and suppressed the rate of recombination of photogenerated electron-hole pairs, leading to a substantial enhancement in photocatalytic performance. X-ray photoelectron spectroscopy, photoluminescence spectra, and electrochemical characterization provide further confirmation that formation of a heterojunction between CTNF@rGO leads to an extension in the lifetimes of the photogenerated charge carriers. The experimental evidence suggests that a p-n heterojunction is the mechanism responsible for the significant photocatalytic activity observed in the CTNF@rGO composite during H2 evolution.
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Affiliation(s)
- Sulakshana Shenoy
- Department of Earth Resources Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Chitiphon Chuaicham
- Department of Earth Resources Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Mariyappan Shanmugam
- Sustainable Energy and Environmental Research Laboratory, Department of Chemistry, Faculty of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India
| | - Takamasa Okumura
- Faculty of Information Science and Electrical Engineering, Kyushu University, Fukuoka 819-035, Japan
| | - Umamahesh Balijapalli
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan
| | - Wei Li
- School of Engineering, Institute for Materials & Processes, The University of Edinburgh, Robert Stevenson Road, Edinburgh EH9 3FB, United Kingdom
| | - Vellaichamy Balakumar
- Department of Chemistry, Sri Ramakrishna College of Arts & Science, Coimbatore 641006, Tamil Nadu, India
| | - Keiko Sasaki
- Department of Earth Resources Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Karthikeyan Sekar
- Sustainable Energy and Environmental Research Laboratory, Department of Chemistry, Faculty of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India
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6
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Lei W, Wang H, Khan S, Suzuki N, Takagi K, Katsumata KI, Teshima K, Terashima C, Fujishima A. Interfacial molecular regulation of TiO 2 for enhanced and stable cocatalyst-free photocatalytic hydrogen production. J Colloid Interface Sci 2023; 645:219-226. [PMID: 37149996 DOI: 10.1016/j.jcis.2023.04.118] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/11/2023] [Accepted: 04/23/2023] [Indexed: 05/09/2023]
Abstract
On the basis of the inherent property limitations of commercial P25-TiO2, many surface interface modification methods have attracted substantial attention for further improving the photocatalytic properties. However, current strategies for designing and modifying efficient photocatalysts (which exhibit complicated manufacturing processes and harsh conditions) are not efficient for production that is low cost, is nontoxic, and exhibits good stability; and therefore restrict practical applications. Herein, a facile and reliable method is reported for in situ amine-containing silane coupling agent functionalization of commercial P25-TiO2 by covalent surface modification for constructing a highly efficient photocatalyst. As a consequence, a high efficiency of H2 evolution was achieved for TiO2-SDA with 0.95 mmol h-1 g-1 (AQE ∼45.6 % at 365 nm) under solar light irradiation without a co-catalyst. The amination modification broadens the light absorption range of the photocatalyst, inhibits the binding of photogenerated carriers, and improves the photocatalytic efficiency; which was verified by photochemical properties and DFT theoretical calculations. This covalent modification method ensures the stability of the photocatalytic reaction. This work provides an approach for molecularly modified photocatalysts to improve photocatalytic performance by covalently modifying small molecules containing amine groups on the photocatalyst surface.
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Affiliation(s)
- Wenwei Lei
- Hebei Key Laboratory of Nano-Biotechnology, School of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, Hebei, China.
| | - Hongji Wang
- Hebei Key Laboratory of Nano-Biotechnology, School of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, Hebei, China
| | - Sovann Khan
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395, Japan
| | - Norihiro Suzuki
- Hebei Key Laboratory of Nano-Biotechnology, School of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, Hebei, China
| | - Kai Takagi
- Research Center for Space System Innovation, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Ken-Ichi Katsumata
- Department of Materials Science and Technology, Faculty of Advanced Engineering Industrial Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Katsuya Teshima
- Research Initiative for Supra-Materials, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Chiaki Terashima
- Research Center for Space System Innovation, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan; Research Initiative for Supra-Materials, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan.
| | - Akira Fujishima
- Research Center for Space System Innovation, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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Akiyama T, Nagakawa H, Tatsuma T. Well-dispersed Au co-catalyst deposited on a rutile TiO 2 photocatalyst via electron traps. Phys Chem Chem Phys 2023; 25:9031-9035. [PMID: 36928706 DOI: 10.1039/d2cp06064g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
We deposited Au nanoparticles as a co-catalyst onto a TiO2 photocatalyst by reducing [AuCl4]- using electrons trapped in the oxygen vacancies of TiO2. The dispersibility and hydrogen production ability of the Au co-catalyst are higher than those prepared using the conventional photodeposition method.
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Affiliation(s)
- Tomoki Akiyama
- Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan.
| | - Haruki Nagakawa
- Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan.
| | - Tetsu Tatsuma
- Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan.
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8
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Khedr TM, El-Sheikh SM, Endo-Kimura M, Wang K, Ohtani B, Kowalska E. Development of Sulfur-Doped Graphitic Carbon Nitride for Hydrogen Evolution under Visible-Light Irradiation. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 13:62. [PMID: 36615972 PMCID: PMC9824438 DOI: 10.3390/nano13010062] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/16/2022] [Accepted: 12/18/2022] [Indexed: 06/17/2023]
Abstract
Developing eco-friendly strategies to produce green fuel has attracted continuous and extensive attention. In this study, a novel gas-templating method was developed to prepare 2D porous S-doped g-C3N4 photocatalyst through simultaneous pyrolysis of urea (main g-C3N4 precursor) and ammonium sulfate (sulfur source and structure promoter). Different content of ammonium sulfate was examined to find the optimal synthesis conditions and to investigate the property-governed activity. The physicochemical properties of the obtained photocatalysts were analyzed by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), scanning transmission electron microscopy (STEM), specific surface area (BET) measurement, ultraviolet-visible light diffuse reflectance spectroscopy (UV/vis DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and reversed double-beam photo-acoustic spectroscopy (RDB-PAS). The as-prepared S-doped g-C3N4 photocatalysts were applied for photocatalytic H2 evolution under vis irradiation. The condition-dependent activity was probed to achieve the best photocatalytic performance. It was demonstrated that ammonium sulfate played a crucial role to achieve concurrently 2D morphology, controlled nanostructure, and S-doping of g-C3N4 in a one-pot process. The 2D nanoporous S-doped g-C3N4 of crumpled lamellar-like structure with large specific surface area (73.8 m2 g-1) and improved electron-hole separation showed a remarkable H2 generation rate, which was almost one order in magnitude higher than that of pristine g-C3N4. It has been found that though all properties are crucial for the overall photocatalytic performance, efficient doping is probably a key factor for high photocatalytic activity. Moreover, the photocatalysts exhibit significant stability during recycling. Accordingly, a significant potential of S-doped g-C3N4 has been revealed for practical use under natural solar radiation.
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Affiliation(s)
- Tamer M. Khedr
- Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan
- Nanomaterials and Nanotechnology Department, Central Metallurgical Research and Development Institute (CMRDI), Cairo 11421, Egypt
| | - Said M. El-Sheikh
- Nanomaterials and Nanotechnology Department, Central Metallurgical Research and Development Institute (CMRDI), Cairo 11421, Egypt
| | - Maya Endo-Kimura
- Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan
| | - Kunlei Wang
- Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan
| | - Bunsho Ohtani
- Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan
| | - Ewa Kowalska
- Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
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9
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Is Black Titania a Promising Photocatalyst? Catalysts 2022. [DOI: 10.3390/catal12111320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Five different (commercial and self-synthesized) titania samples were mixed with NaBH4 and then heated to obtain black titania samples. The change in synthesis conditions resulted in the preparation of nine different photocatalysts, most of which were black in color. The photocatalysts were characterized by various methods, including X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), photoacoustic and reverse-double beam photoacoustic spectroscopy (PAS/RDB-PAS). The photocatalytic activity was tested for oxidative decomposition of acetic acid, methanol dehydrogenation, phenol degradation and bacteria inactivation (Escherichia coli) under different conditions, i.e., irradiation with UV, vis, and NIR, and in the dark. It was found that the properties of the obtained samples depended on the features of the original titania materials. A shift in XRD peaks was observed only in the case of the commercial titania samples, indicating self-doping, whereas faceted anatase samples (self-synthesized) showed high resistance towards bulk modification. Independent of the type and degree of modification, all modified samples exhibited much worse activity under UV irradiation than original titania photocatalysts both under aerobic and anaerobic conditions. It is proposed that the strong reduction conditions during the samples’ preparation resulted in the partial destruction of the titania surface, as evidenced by both microscopic observation and crystallographic data (an increase in amorphous content), and thus the formation of deep electron traps (bulk defects as oxygen vacancies) increasing the charge carriers’ recombination. Under vis irradiation, a slight increase in photocatalytic performance (phenol degradation) was obtained for only four samples, while two samples also exhibited slight activity under NIR. In the case of bacteria inactivation, some modified samples exhibited higher activity under both vis and NIR than respective pristine titania, which could be useful for disinfection, cancer treatment and other purposes. However, considering the overall performance of the black titania samples in this study, it is difficult to recommend them for broad environmental applications.
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Wang R, Che G, Wang C, Liu C, Liu B, Ohtani B, Liu Y, Zhang X. Alcohol Plasma Processed Surface Amorphization for Photocatalysis. ACS Catal 2022. [DOI: 10.1021/acscatal.2c03427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rui Wang
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024, People’s Republic of China
| | - Guangshun Che
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024, People’s Republic of China
| | - Changhua Wang
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024, People’s Republic of China
| | - Chunyao Liu
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024, People’s Republic of China
| | - Baoshun Liu
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, No. 122, Luoshi Road, Wuhan 430070, People’s Republic of China
| | - Bunsho Ohtani
- Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Yichun Liu
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024, People’s Republic of China
| | - Xintong Zhang
- Key Laboratory of UV-Emitting Materials and Technology of Chinese Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024, People’s Republic of China
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11
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Reversed double-beam photoacoustic spectroscopic analysis of photoinduced change in absorption of cellulose fibres. Sci Rep 2022; 12:14475. [PMID: 36008458 PMCID: PMC9411129 DOI: 10.1038/s41598-022-18749-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/18/2022] [Indexed: 11/20/2022] Open
Abstract
Photoabsorption properties of cellulose fibres under continuous and modulated irradiation were investigated in situ by the use of reversed double-beam photoacoustic spectroscopy (RDB-PAS). This photoacoustic (PA) measurement enabled observation of ultraviolet- and visible light-induced, electron trap filling, and reductive change on the surface of the fibres. Energy-resolved measurements and analysis of the kinetics of photoinduced de-excitation suggested that electrons that accumulated in the different cellulose crystalline phases had moderate reactivity toward molecular oxygen. Saturation limits of the intensities of the PA and RDB-PAS signals under de-aerated conditions in the presence of surface-adsorbed methanol were estimated for softwood and hardwood cellulose samples. The results suggest that the RDB-PAS technique is a feasible method for the estimation of the electron trap distribution, which is a potential measure of the density of crystalline cellulose defects.
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12
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TiO2/Au/TiO2 Plasmonic Photocatalysts: The Influence of Titania Matrix and Gold Properties. INVENTIONS 2022. [DOI: 10.3390/inventions7030054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Plasmonic photocatalysts have gained more and more attention because of possible applications for solar energy conversion, environmental decontamination, and water treatment. However, the activity under visible light is usually very low, and the property-governed activity as well as the mechanisms are not fully understood yet. Accordingly, this study examines four different titania photocatalysts (anatase and rutile with fine and large crystallites) modified with gold by photodeposition. Three kinds of samples were prepared, as follows: (i) gold-modified titania (Au/TiO2), (ii) physically mixed Au/TiO2 samples (Au/TiO2(1) + Au/TiO2(2)), and (iii) Au/(TiO2(1) + Au/TiO2(2)) samples, prepared by subsequent deposition of gold on the mixture of bare and gold-modified titania. In total, twelve samples were prepared and well characterized, including diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM). The photocatalytic activity was examined in three reaction systems: (i) methanol dehydrogenation during gold photodeposition under UV/vis irradiation, (ii) oxidative decomposition of acetic acid (UV/vis), and (iii) oxidation of 2-propanol to acetone under visible light irradiation (λ > 450 nm). It was found that during subsequent deposition, gold is mainly formed on the surface of pre-deposited Au nanoparticles (NPs), localized on fine titania NPs, through the electrostatic attractions (negatively charged gold resulting from photogenerated electrons’ accumulation). This gold aggregation, though detrimental for UV activity (many “naked” large titania with low activity), is highly beneficial for vis activity because of efficient light harvesting and increased interface between gold and titania (gold deposits surrounded by fine titania NPs). Moreover, it was found that rutile is more active than anatase for plasmonic photocatalysis, probably due to easier electron transfer from gold via titania to adsorbed oxygen (more negative conduction band), which might hinder the back reaction (electron transfer: Au→TiO2→Au).
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13
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Yoshiiri K, Karabiyik B, Wang K, Wei Z, Colbeau-Justin C, Kowalska E. The property-governed activity of silver-modified titania photocatalysts: The influence of titania matrix. J Chem Phys 2022; 156:244706. [DOI: 10.1063/5.0097762] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Commercial titania photocatalysts were modified with silver nanoparticles (NPs) by the photodeposition method in the presence/absence of methanol. The obtained photocatalysts were characterized by XRD, XPS, diffuse reflectance spectroscopy, STEM, and time-resolved microwave conductivity (TRMC) methods. The photocatalytic activity was tested under UV/vis irradiation for (i) methanol dehydrogenation (during silver deposition), (ii) oxygen evolution with in situ silver deposition, and (iii) oxidative decomposition of acetic acid, as well as under vis irradiation for 2-propanol oxidation. The action spectra of 2-propanol oxidation were also performed. It has been confirmed that modification of titania with silver causes significant improvement of photocatalytic activity under both UV and vis irradiation as silver works as an electron scavenger (TRMC data) and vis activator (possibly by an energy transfer mechanism). The obtained activities differ between titania samples significantly, suggesting that the type of crystalline phase, particle/crystallite sizes, and electron traps’ density are crucial for both the properties of formed silver deposits and resultant photocatalytic activity. It might be concluded that, under UV irradiation, (i) high crystallinity and large specific surface area are recommended for rutile- and anatase-rich samples, respectively, during hydrogen evolution, (ii) mixed crystalline phases cause a high rate of oxygen evolution from water, and (iii) anatase phase with fine silver NPs results in efficient decomposition of acetic acid, whereas under vis irradiation the aggregated silver NPs (broad localized surface plasmon resonance peak) on the rutile phase are promising for oxidation reactions.
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Affiliation(s)
- Kenta Yoshiiri
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan
- Institute for Catalysis (ICAT), Hokkaido University, Sapporo, Japan
| | - Baris Karabiyik
- Institute for Catalysis (ICAT), Hokkaido University, Sapporo, Japan
| | - Kunlei Wang
- Institute for Catalysis (ICAT), Hokkaido University, Sapporo, Japan
- Northwest Research Institute, Co. Ltd. of C.R.E.C., Lanzhou, China
| | - Zhishun Wei
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan, People's Republic of China
| | | | - Ewa Kowalska
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan
- Institute for Catalysis (ICAT), Hokkaido University, Sapporo, Japan
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14
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Uesugi Y, Nagakawa H, Nagata M. Highly Efficient Photocatalytic Degradation of Hydrogen Sulfide in the Gas Phase Using Anatase/TiO 2(B) Nanotubes. ACS OMEGA 2022; 7:11946-11955. [PMID: 35449917 PMCID: PMC9016837 DOI: 10.1021/acsomega.1c07294] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 03/22/2022] [Indexed: 06/14/2023]
Abstract
Hydrogen sulfide (H2S) is a highly toxic and corrosive gas that causes a foul odor even at very low concentrations [several parts per billion (ppb)]. However, industrially discharged H2S has a concentration range of several tens of ppb to several parts per million (ppm), which conventional methods are unable to process. Therefore, advanced and sustainable methods for treating very low concentrations of H2S are urgently needed. TiO2-based photocatalysts are eco-friendly and have the ability to treat environmental pollutants, such as low-concentration gases, using light energy. However, there are no reports on H2S decomposition or oxidation at concentrations below several ppb. Therefore, in this study, we employed anatase/TiO2(B) nanotubes, which have a high specific surface area and an efficient charge-transfer interface, to treat H2S. We successfully reduced 10 ppm of H2S to 1 ppb or less at a kinetic rate of 75 μmol h-1 g-1. The suitability of our method was further demonstrated by the generation of sulfate ions and sulfur (as detected by X-ray photoelectron spectroscopy and ion chromatography), which are industrially useful as oxidation products, whereas sulfur dioxide, a harmful substance, was not produced. This is the first study to report H2S decomposition down to the ppb level, providing meaningful solutions for malodor problems and potential health hazards associated with H2S.
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15
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Ohtani B, Takashima M. Happy photocatalysts and unhappy photocatalysts: electron trap-distribution analysis for metal oxide-sample identification. Catal Sci Technol 2022. [DOI: 10.1039/d1cy01955d] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An attempt to identify inorganic solids, such as metal oxides, using ERDT (energy-resolved distribution of electron traps)/CBB (conduction-band bottom) patterns, measured by reversed double-beam spectroscopy, as a “fingerprint” is introduced.
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Affiliation(s)
- Bunsho Ohtani
- Institute for Catalysis, Hokkaido University, Sapporo 001-0021, Japan
| | - Mai Takashima
- Institute for Catalysis, Hokkaido University, Sapporo 001-0021, Japan
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16
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Kojima R, Ohtani B, Tada H. Photocatalytic Activity of Radial Rutile Titanium(IV) Oxide Microspheres for Aerobic Oxidation of Organics. Chemphyschem 2021; 23:e202100793. [PMID: 34918451 DOI: 10.1002/cphc.202100793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 12/08/2021] [Indexed: 11/07/2022]
Abstract
Radial rutile TiO2 nanorod homomesocrystals (TiO2 -NR HOMCs) or the so-called "sea urchin-like TiO2 microspheres" were synthesized by using a hydrothermal method. TiO2 -NR HOMCs show photocatalytic activity for aerobic oxidative degradation of 2-naphthol under irradiation of UV- and visible light. Furthermore, extremely small iron oxide clusters were formed on the surface of TiO2 -NR HOMCs (FeOx /TiO2 -NR HOMCs) by the chemisorption-calcination technique to reduce the band gap. The FeOx -surface modification gives rise to drastic enhancement of the UV- and visible-light activity. Reversed double-beam photoacoustic spectroscopy measurements were performed for TiO2 -NR HOMCs and FeOx /TiO2 -NR HOMCs to obtain the ERDT (energy-resolved distribution of electron traps)/CBB (conduction-band bottom) patterns. The ERDT/CBB pattern of TiO2 -NR HOMCs consists of two components derived from rutile (C1) and amorphous TiO2 (C2). In the pattern, the surface electron traps in C2 exist near the CBB to be removed by the FeOx -surface modification. By taking this finding into consideration, the striking surface modification effect is ascribable to the electrocatalytic activity (or the action as an electron reservoir) of the FeOx clusters for multiple ORR, the suppression of recombination, and the increase in the visible-light harvesting efficiency.
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Affiliation(s)
- Ryota Kojima
- Graduate School of Science and Engineering, Kindai University, 3-4-1, Kowakae, 577-8502, Higashi-Osaka, Osaka, Japan
| | - Bunsho Ohtani
- Graduate School of Environmental Science, Hokkaido University, 060-0810, Sapporo, Hokkaido, Japan.,Institute for Catalysis, Hokkaido University, 001-0021, Sapporo, Hokkaido, Japan
| | - Hiroaki Tada
- Graduate School of Science and Engineering, Kindai University, 3-4-1, Kowakae, 577-8502, Higashi-Osaka, Osaka, Japan
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17
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Abstract
Decahedral anatase particles (DAPs) have been prepared by the gas-phase method, characterized, and analyzed for property-governed photocatalytic activity. It has been found that depending on the reaction systems, different properties control the photocatalytic activity, that is, the particle aspect ratio, the density of electron traps and the morphology seem to be responsible for the efficiency of water oxidation, methanol dehydrogenation and oxidative decomposition of acetic acid, respectively. For the discussion on the dependence of the photocatalytic activity on the morphology and/or the symmetry other titania-based photocatalysts have also been analyzed, that is, octahedral anatase particles (OAP), commercial titania P25, inverse opal titania with and without incorporated gold NPs in void spaces and plasmonic photocatalysts (titania with deposits of gold). It has been concluded that though the morphology governs photocatalytic activity, the symmetry (despite its importance in many cases) rather does not control the photocatalytic performance.
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18
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Chen G, Takashima M, Ohtani B. Direct Amorphous-structure Analysis: How are Surface/Bulk Structure and Activity of Titania Photocatalyst Particles Changed by Milling? CHEM LETT 2021. [DOI: 10.1246/cl.200825] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Guangyi Chen
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Mai Takashima
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
- Institute for Catalysis, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan
| | - Bunsho Ohtani
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
- Institute for Catalysis, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan
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19
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Kobielusz M, Nitta A, Macyk W, Ohtani B. Combined Spectroscopic Methods of Determination of Density of Electronic States: Comparative Analysis of Diffuse Reflectance Spectroelectrochemistry and Reversed Double-Beam Photoacoustic Spectroscopy. J Phys Chem Lett 2021; 12:3019-3025. [PMID: 33733790 PMCID: PMC8041308 DOI: 10.1021/acs.jpclett.1c00262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 03/04/2021] [Indexed: 06/12/2023]
Abstract
The diffuse reflectance spectroelectrochemistry (SE-DRS) and reversed double-beam photoacoustic spectroscopy (RDB-PAS) provide unique, complementary information on the density of electronic states (DOS) in the vicinity of the conduction band bottom. The measurements are performed under quite different conditions, representing the solid/liquid and solid/gas interfaces in SE-DRS and RDB-PAS, respectively. DOS profiles obtained from both types of measurements can be considered as unique "fingerprints" of the tested materials. The analysis of DOS profiles recorded for 16 different TiO2 samples confirms that both methods similarly describe the shapes of DOS profiles around the conduction band edges. The states characterized by energy higher than VBT (valence-band top) + Eg can be considered as electronic states within the conduction band. Recognition of the potential of the conduction band bottom allows one to classify the electronic states as deep or shallow electron traps or conduction band states, which play different roles in photocatalysis. The comparative analysis shows that both methods provide very useful information which can be used in understanding and predicting the photo(electro)catalytic reactivity of semiconductors.
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Affiliation(s)
- Marcin Kobielusz
- Faculty
of Chemistry, Jagiellonian University, ul. Gronostajowa 2, 30-387 Kraków, Poland
| | - Akio Nitta
- Institute
for Catalysis, Hokkaido University, Sapporo 001-0021, Japan
- Graduate
School of Environmental Science, Hokkaido
University, Sapporo 060-0810, Japan
| | - Wojciech Macyk
- Faculty
of Chemistry, Jagiellonian University, ul. Gronostajowa 2, 30-387 Kraków, Poland
| | - Bunsho Ohtani
- Institute
for Catalysis, Hokkaido University, Sapporo 001-0021, Japan
- Graduate
School of Environmental Science, Hokkaido
University, Sapporo 060-0810, Japan
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20
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Nagakawa H, Nagata M. Elucidating the Factors Affecting Hydrogen Production Activity Using a CdS/TiO 2 Type-II Composite Photocatalyst. ACS OMEGA 2021; 6:4395-4400. [PMID: 33644552 PMCID: PMC7906583 DOI: 10.1021/acsomega.0c05749] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 01/20/2021] [Indexed: 06/12/2023]
Abstract
CdS/TiO2 is a composite photocatalyst that has been studied over many years and in which electron transfer from CdS to TiO2 is believed to lead to high photocatalytic activity. However, most reports on improved activity involve hydrogen production in the presence of a sulfide reducing agent. In this study, we comprehensively examined the effects of electron transfer, hydrogen overvoltage, substrate adsorption, and the cocatalyst from relationships between hydrogen production ability and the total number of trapped electrons in the presence of various reducing agents. As a result, we clarified that the electron transfer between CdS and TiO2 does not necessarily lead to high activity. We showed that the composite photocatalyst needs to be designed for the intended purpose and that evaluating the hydrogen production ability using sacrificial reagents provides insufficient information for use in an actual environment.
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Affiliation(s)
- Haruki Nagakawa
- Department of Industrial Chemistry, Graduate School of Engineering, Tokyo University of Science, 12-1 Ichigayafunagawara-cho, Shinjuku-ku, Tokyo 162-0826, Japan
| | - Morio Nagata
- Department of Industrial Chemistry, Graduate School of Engineering, Tokyo University of Science, 12-1 Ichigayafunagawara-cho, Shinjuku-ku, Tokyo 162-0826, Japan
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21
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Shen Y, Nitta A, Takashima M, Ohtani B. Do Particles Interact Electronically? —Proof of Interparticle Charge-transfer Excitation between Adjoined Anatase and Rutile Particles. CHEM LETT 2021. [DOI: 10.1246/cl.200636] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yang Shen
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Akio Nitta
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Mai Takashima
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
- Institute for Catalysis, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan
| | - Bunsho Ohtani
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
- Institute for Catalysis, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan
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22
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Velo-Gala I, Torres-Pinto A, Silva CG, Ohtani B, Silva AMT, Faria JL. Graphitic carbon nitride photocatalysis: the hydroperoxyl radical role revealed by kinetic modelling. Catal Sci Technol 2021. [DOI: 10.1039/d1cy01657a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The behaviour of graphitic carbon nitride photocatalysis for phenol removal and H2O2 evolution was fully analysed by kinetic modelling, rediscovering the contribution of oxygen, reactive oxygen species, photogenerated holes and intermediate products.
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Affiliation(s)
- Inmaculada Velo-Gala
- Laboratory of Separation and Reaction Engineering – Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia, Universidade do Porto, Porto 4200-465, Portugal
| | - André Torres-Pinto
- Laboratory of Separation and Reaction Engineering – Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia, Universidade do Porto, Porto 4200-465, Portugal
| | - Cláudia G. Silva
- Laboratory of Separation and Reaction Engineering – Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia, Universidade do Porto, Porto 4200-465, Portugal
| | - Bunsho Ohtani
- Institute for Catalysis, Hokkaido University, Sapporo 001-0021, Japan
| | - Adrián M. T. Silva
- Laboratory of Separation and Reaction Engineering – Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia, Universidade do Porto, Porto 4200-465, Portugal
| | - Joaquim L. Faria
- Laboratory of Separation and Reaction Engineering – Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia, Universidade do Porto, Porto 4200-465, Portugal
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23
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Sano K, Kuttassery F, Shimada T, Ishida T, Takagi S, Ohtani B, Yamakata A, Honma T, Tachibana H, Inoue H. Optically Transparent Colloidal Dispersion of Titania Nanoparticles Storable for Longer than One Year Prepared by Sol/Gel Progressive Hydrolysis/Condensation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:44743-44753. [PMID: 32915534 DOI: 10.1021/acsami.0c12951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The molecular catalyst sensitized system (MCSS), where an excited molecular catalyst adsorbed on a semiconductor such as TiO2 injects electrons to the conduction band of the semiconductor leading to hydrogen evolution/CO2 reduction coupled with an oxidation of water on the molecular catalyst, has been one of the most probable candidates in the approach to artificial photosynthesis. For a full utilization of visible light, however, a serious light scattering of the aqueous suspension of TiO2 in the visible region, which is generally experienced, should be avoided. Here, we report a preparation of optically transparent colloidal dispersion of TiO2 by the sol/gel reaction of TiCl4 through progressive hydrolysis/condensation under the basic condition without any calcination processes. The TiO2 nanoparticles (TiO2(NPs)) obtained were characterized as an amorphous particle (∼10-15 nm) having a microcrystal domain of anatase within several nm by XRD, Raman spectroscopies, XRF, XAFS, TG/DTA, and HRTEM, respectively. The energy-resolved distribution of carrier electron traps in TiO2(NPs) as a fingerprint of TiO2 was characterized through reversed double-beam photo-acoustic spectroscopy to have a close similarity to that of TiO2(ST-01) as well as the observation of carrier traps by transient absorption spectroscopy. Though the powder TiO2(NP) itself was not dispersed well in aqueous solution, the wet TiO2(NPs) as prepared before being dried up provided a completely transparent aqueous dispersion under the acidic condition (1 M HCl). Addition of methanol enabled the colloidal dispersion (TiO2(NPs, MeOH/H2O, 0.1 M HCl)) to keep the optical transparency for longer than 1 year (550 days), which is the first example of TiO2 dispersion storable for such a long period. TiO2(NPs, MeOH/H2O) exhibited a moderate photocatalytic reactivity of H2 evolution with a quantum yield of ∼2.6% upon 365 nm light irradiation. An optically transparent thin film of TiO2(NPs, MeOH/H2O) was also successfully prepared on a glass plate to exhibit an enhanced hydrophilicity upon UV light irradiation.
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Affiliation(s)
- Keito Sano
- Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachiohji, Tokyo 192-0397, Japan
| | - Fazalurahman Kuttassery
- Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachiohji, Tokyo 192-0397, Japan
| | - Tetsuya Shimada
- Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachiohji, Tokyo 192-0397, Japan
| | - Tamao Ishida
- Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachiohji, Tokyo 192-0397, Japan
| | - Shinsuke Takagi
- Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachiohji, Tokyo 192-0397, Japan
| | - Bunsho Ohtani
- Institute for catalysis Hokkaido University, North 21, West 10, Sapporo 001-0021, Japan
| | - Akira Yamakata
- Toyota Technological Institute, 2-12-1, Hisakata, Tempaku, Nagoya 468-8511, Japan
| | - Tetsuo Honma
- Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Hiroshi Tachibana
- Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachiohji, Tokyo 192-0397, Japan
| | - Haruo Inoue
- Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachiohji, Tokyo 192-0397, Japan
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24
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Yu F, Wang C, Li Y, Ma H, Wang R, Liu Y, Suzuki N, Terashima C, Ohtani B, Ochiai T, Fujishima A, Zhang X. Enhanced Solar Photothermal Catalysis over Solution Plasma Activated TiO 2. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2000204. [PMID: 32832348 PMCID: PMC7435248 DOI: 10.1002/advs.202000204] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 05/25/2020] [Indexed: 05/22/2023]
Abstract
Colored wide-bandgap semiconductor oxides with abundant mid-gap states have long been regarded as promising visible light responsive photocatalysts. However, their catalytic activities are hampered by charge recombination at deep level defects, which constitutes the critical challenge to practical applications of these oxide photocatalysts. To address the challenge, a strategy is proposed here that includes creating shallow-level defects above the deep-level defects and thermal activating the migration of trapped electrons out of the deep-level defects via these shallow defects. A simple and scalable solution plasma processing (SPP) technique is developed to process the presynthesized yellow TiO2 with numerous oxygen vacancies (Ov), which incorporates hydrogen dopants into the TiO2 lattice and creates shallow-level defects above deep level of Ov, meanwhile retaining the original visible absorption of the colored TiO2. At elevated temperature, the SPP-treated TiO2 exhibits a 300 times higher conversion rate for CO2 reduction under solar light irradiation and a 7.5 times higher removal rate of acetaldehyde under UV light irradiation, suggesting the effectiveness of the proposed strategy to enhance the photoactivity of colored wide-bandgap oxides for energy and environmental applications.
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Affiliation(s)
- Fei Yu
- Key Laboratory of UV‐Emitting Materials and Technology of Chinese Ministry of EducationNortheast Normal UniversityChangchun130024China
| | - Changhua Wang
- Key Laboratory of UV‐Emitting Materials and Technology of Chinese Ministry of EducationNortheast Normal UniversityChangchun130024China
| | - Yingying Li
- Key Laboratory of UV‐Emitting Materials and Technology of Chinese Ministry of EducationNortheast Normal UniversityChangchun130024China
| | - He Ma
- Key Laboratory of UV‐Emitting Materials and Technology of Chinese Ministry of EducationNortheast Normal UniversityChangchun130024China
| | - Rui Wang
- Key Laboratory of UV‐Emitting Materials and Technology of Chinese Ministry of EducationNortheast Normal UniversityChangchun130024China
| | - Yichun Liu
- Key Laboratory of UV‐Emitting Materials and Technology of Chinese Ministry of EducationNortheast Normal UniversityChangchun130024China
| | - Norihiro Suzuki
- Photocatalysis International Research CenterResearch Institute for Science & TechnologyTokyo University of Science2641 YamazakiNodaChiba278‐8510Japan
| | - Chiaki Terashima
- Photocatalysis International Research CenterResearch Institute for Science & TechnologyTokyo University of Science2641 YamazakiNodaChiba278‐8510Japan
| | - Bunsho Ohtani
- Graduate School of Environmental ScienceHokkaido UniversitySapporo060‐0810Japan
| | - Tsuyoshi Ochiai
- Materials Analysis GroupKawasaki Technical Support DepartmentLocal Independent Administrative Agency Kanagawa Institute of industrial Science and Technology (KISTEC)Kanagawa213‐0012Japan
| | - Akira Fujishima
- Photocatalysis International Research CenterResearch Institute for Science & TechnologyTokyo University of Science2641 YamazakiNodaChiba278‐8510Japan
| | - Xintong Zhang
- Key Laboratory of UV‐Emitting Materials and Technology of Chinese Ministry of EducationNortheast Normal UniversityChangchun130024China
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25
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Zheng Z, Murakami N, Liu J, Teng Z, Zhang Q, Cao Y, Cheng H, Ohno T. Development of Plasmonic Photocatalyst by Site‐selective Loading of Bimetallic Nanoparticles of Au and Ag on Titanium(IV) Oxide. ChemCatChem 2020. [DOI: 10.1002/cctc.202000366] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Zhi Zheng
- Department of Applied Chemistry Faculty of EngineeringKyushu Institute of Technology 1-1 Sensuicho, Tobata Kitakyushu 804-8550 Japan
- School of Mechanical EngineeringYangzhou University Yangzhou 225127 P.R. China
| | - Naoya Murakami
- Department of Applied Chemistry Faculty of EngineeringKyushu Institute of Technology 1-1 Sensuicho, Tobata Kitakyushu 804-8550 Japan
- Graduate School of Life Science and Systems EngineeringKyushu Institute of Technology 2-4 Hibikino, Wakamatsu-ku Kitakyushu 808-0196 Japan
| | - Jingjing Liu
- School of Mechanical EngineeringYangzhou University Yangzhou 225127 P.R. China
| | - Zhenyuan Teng
- Department of Applied Chemistry Faculty of EngineeringKyushu Institute of Technology 1-1 Sensuicho, Tobata Kitakyushu 804-8550 Japan
| | - Qitao Zhang
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education Institute of Microscale OptoelectronicsShenzhen University Shenzhen 518060 P.R. China
| | - Yu Cao
- Department of Applied Chemistry Faculty of EngineeringKyushu Institute of Technology 1-1 Sensuicho, Tobata Kitakyushu 804-8550 Japan
| | - Honghui Cheng
- School of Mechanical EngineeringYangzhou University Yangzhou 225127 P.R. China
| | - Teruhisa Ohno
- Department of Applied Chemistry Faculty of EngineeringKyushu Institute of Technology 1-1 Sensuicho, Tobata Kitakyushu 804-8550 Japan
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26
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Nagakawa H, Ochiai T, Ma H, Wang C, Zhang X, Shen Y, Takashima M, Ohtani B, Nagata M. Elucidation of the electron energy structure of TiO 2(B) and anatase photocatalysts through analysis of electron trap density. RSC Adv 2020; 10:18496-18501. [PMID: 35517202 PMCID: PMC9053729 DOI: 10.1039/d0ra02587a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 05/07/2020] [Indexed: 11/21/2022] Open
Abstract
A clear understanding of the electron energy structure of TiO2(B)/anatase is needed to study the related catalytic reactions and design new composite photocatalysts. In this study, the electron energy structures of TiO2(B) and anatase were estimated by analyzing the energy-resolved distribution of electron traps measured by reversed double-beam photoacoustic spectroscopy. In the mixture of TiO2(B) and anatase, interfacial charge-transfer excitation from anatase to electron traps of TiO2(B) was suggested. By analyzing this for TiO2(B), the electron level with a relatively high density of states was found to be located ∼0.07 eV deeper than that for anatase. Furthermore, a similar electron energy structure was suggested for a composite photocatalyst having a mixed phase of TiO2(B) and anatase. The electron energy structures of TiO2(B) and anatase were estimated by analyzing the energy-resolved distribution of electron traps.![]()
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Affiliation(s)
- Haruki Nagakawa
- Department of Industrial Chemistry, Graduate School of Engineering, Tokyo University of Science 12-1 Ichigayafunagawara-cho, Shinjuku-ku Tokyo 162-0826 Japan
| | - Tsuyoshi Ochiai
- Materials Analysis Group, Research and Development Department, Local Independent Administrative Agency, Kanagawa Institute of industrial Science and TEChnology (KISTEC) Kanagawa 213-0012 Japan.,Photocatalysis International Research Center, Tokyo University of Science Chiba 278-8510 Japan
| | - He Ma
- Center for Advanced Optoelectronic Functional Materials Research, Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University Changchun 130024 China
| | - Changhua Wang
- Center for Advanced Optoelectronic Functional Materials Research, Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University Changchun 130024 China
| | - Xintong Zhang
- Center for Advanced Optoelectronic Functional Materials Research, Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University Changchun 130024 China
| | - Yang Shen
- Graduate School of Environmental Science, Hokkaido University Sapporo 060-0810 Japan
| | - Mai Takashima
- Graduate School of Environmental Science, Hokkaido University Sapporo 060-0810 Japan.,Institute for Catalysis, Hokkaido University Sapporo 001-0021 Japan +81-11-706-9133
| | - Bunsho Ohtani
- Graduate School of Environmental Science, Hokkaido University Sapporo 060-0810 Japan.,Institute for Catalysis, Hokkaido University Sapporo 001-0021 Japan +81-11-706-9133
| | - Morio Nagata
- Department of Industrial Chemistry, Graduate School of Engineering, Tokyo University of Science 12-1 Ichigayafunagawara-cho, Shinjuku-ku Tokyo 162-0826 Japan
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Chuaicham C, Karthikeyan S, Pawar RR, Xiong Y, Dabo I, Ohtani B, Kim Y, Song JT, Ishihara T, Sasaki K. Energy-resolved distribution of electron traps for O/S-doped carbon nitrides by reversed double-beam photoacoustic spectroscopy and the photocatalytic reduction of Cr(vi). Chem Commun (Camb) 2020; 56:3793-3796. [PMID: 32129327 DOI: 10.1039/c9cc09988c] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report for the first time to our knowledge the identification of heteroatom-doped and undoped C3N4 with the energy-resolved distribution of electron traps (ERDT) near the conduction band bottom position (CBB) using reversed double-beam photoacoustic spectroscopy. The ERDT/CBB pattern is used to classify the type of elemental doping in C3N4, related to photocatalytic efficiency.
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Affiliation(s)
- Chitiphon Chuaicham
- Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan.
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Chuaicham C, Karthikeyan S, Song JT, Ishihara T, Ohtani B, Sasaki K. Importance of ZnTiO 3 Phase in ZnTi-Mixed Metal Oxide Photocatalysts Derived from Layered Double Hydroxide. ACS APPLIED MATERIALS & INTERFACES 2020; 12:9169-9180. [PMID: 32064859 DOI: 10.1021/acsami.9b18785] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this study, ZnTi-mixed metal oxides (ZTM), such as ZnTiO3, were synthesized from ZnTi layered double hydroxides by varying the molar ratio of Zn/Ti, calcination temperatures, and synthesis methods (hydrothermal or reflux). The surface electronic characteristics of ZTM were investigated by the energy-resolved distribution of electron traps (ERDTs) using reversed double-beam photoacoustic spectroscopy. The ZTM samples obtained by conducting hydrothermal synthesis at 500 °C showed similar ERDT patterns independent of the molar ratio of Zn/Ti, although ZnTiO3 phase was not observed in the X-ray diffraction pattern, when the Zn/Ti ratio was high. When the ERDT patterns demonstrated a high electron accumulation level near the conduction band bottom in hydrothermal products at 500 °C, a higher photocatalytic phenol degradation efficiency was observed due to the formation of ZnTiO3 phase. This suggested that the product with the high Zn/Ti molar ratio (Zn/Ti = 6) constituted amorphous ZnTiO3.The enhanced photocatalytic performance of ZTM could be attributed to the heterojunction of electrons among ZnO, TiO2, and ZnTiO3, which enabled electron transfer in the composites, prevented charge recombination, and promoted a wider visible light adsorption by ZnTiO3 phase irrespective of its crystallinity.
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Affiliation(s)
- Chitiphon Chuaicham
- Department of Earth Resources Engineering, Faculty of Engineering , Kyushu University , 744 Motooka, Nishiku , Fukuoka 819-0395 , Japan
| | - Sekar Karthikeyan
- Department of Earth Resources Engineering, Faculty of Engineering , Kyushu University , 744 Motooka, Nishiku , Fukuoka 819-0395 , Japan
| | - Jun Tae Song
- Department of Applied Chemistry, Faculty of Engineering , Kyushu University , 744 Motooka, Nishiku , Fukuoka 819-0395 , Japan
- International Institute for Carbon-Neutral Energy Research (I2CNER) , 744 Motooka, Nishiku , Fukuoka 819-0395 , Japan
| | - Tatsumi Ishihara
- Department of Applied Chemistry, Faculty of Engineering , Kyushu University , 744 Motooka, Nishiku , Fukuoka 819-0395 , Japan
- International Institute for Carbon-Neutral Energy Research (I2CNER) , 744 Motooka, Nishiku , Fukuoka 819-0395 , Japan
| | - Bunsho Ohtani
- Institute for Catalysis , Hokkaido University , Sapporo 001-0021 , Japan
| | - Keiko Sasaki
- Department of Earth Resources Engineering, Faculty of Engineering , Kyushu University , 744 Motooka, Nishiku , Fukuoka 819-0395 , Japan
- Institute for Catalysis , Hokkaido University , Sapporo 001-0021 , Japan
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29
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Carbon/Graphene-Modified Titania with Enhanced Photocatalytic Activity under UV and Vis Irradiation. MATERIALS 2019; 12:ma12244158. [PMID: 31835760 PMCID: PMC6947090 DOI: 10.3390/ma12244158] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 11/28/2019] [Accepted: 12/09/2019] [Indexed: 11/18/2022]
Abstract
Laser synthesis was used for one-step synthesis of titania/graphene composites (G-TiO2 (C)) from a suspension of 0.04 wt% commercial reduced graphene oxide (rGO) dispersed in liquid titanium tetraisopropoxide (TTIP). Reference titania sample (TiO2(C)) was prepared by the same method without graphene addition. Both samples and commercial titania P25 were characterized by various methods and tested under UV/vis irradiation for oxidative decomposition of acetic acid and dehydrogenation of methanol (with and without Pt co-catalyst addition), and under vis irradiation for phenol degradation and inactivation of Escherichia coli. It was found that both samples (TiO2(C) and G-TiO2(C)) contained carbon resulting from TTIP and C2H4 (used as a synthesis sensitizer), which activated titania towards vis activity. The photocatalytic activity under UV/vis irradiation was like that by P25. The highest activity of TiO2(C) sample for acetic acid oxidation was probably caused by its surface enrichment with hydroxyl groups. G-TiO2(C) was the most active for methanol dehydrogenation in the absence of platinum (ca. five times higher activity than that by TiO2(C) and P25), suggesting that graphene works as a co-catalyst for hydrogen evolution. High activity under both UV and vis irradiation for decomposition of organic compounds, hydrogen evolution and inactivation of bacteria suggests that laser synthesis allows preparation of cheap (carbon-modified) and efficient photocatalysts for broad environmental applications.
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Correlation of the Photocatalytic Activities of Cu, Ce and/or Pt-Modified Titania Particles with their Bulk and Surface Structures Studied by Reversed Double-Beam Photoacoustic Spectroscopy. Catalysts 2019. [DOI: 10.3390/catal9121010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Modified titania photocatalyst powder samples were prepared using the sol-gel method for copper (Cu) and cerium (Ce) doping and impregnation for platinum (Pt) loading. Their bulk crystalline structures were investigated using X-ray diffractometry (XRD) with the Rietveld analysis. The surface/bulk structure, surface properties, and morphologies were observed using reversed double-beam photoacoustic spectroscopy (RDB-PAS), nitrogen adsorption, and scanning electron microscopy, respectively. The results from the XRD revealed that all samples were mainly anatase (ca. 80% or higher) with small amounts of rutile and non-crystalline components. The specific surface areas of all samples were in the range of 115–155 m2 g−1. Ce and Cu species were mainly distributed, while Pt was potentially loaded as a partially oxidized form on the titania surface. The results from the RDB-PAS indicated the changing of the energy-resolved distribution of electron traps (ERDT) from the original titania surface upon doping of the metals (Cu, Ce, and Pt), which altered their catalytic activities. The metals photocatalytic activities with UV irradiation were measured in two representative reactions; (a) CO2 evolution from acetic acid under the aerobic condition and (b) H2 evolution from deaerated aqueous methanol. In reaction (a), the Cu and/or Ce modification gave almost the same or slightly lower activity compared to the non-modified titania samples, while platinum loading yielded ca. 5–6 times higher activity. For reaction (b), the photocatalytic tests were divided into two sets; without (b1) and with (b2) Pt deposition during the reaction. Similar enhancements of activity from the Pt loading sample (and by Cu modification) were observed in reaction (b1) without in-situ platinum deposition, while the unmodified and Ce-doped samples were almost inactive. For the activities of reaction (b2) with in-situ platinum deposition, the unmodified samples showed the highest activity while the Cu-modified samples showed significantly lower activity.
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Das A, Saha S, Panigrahi K, Ghorai UK, Chattopadhyay KK. Enhanced Photoluminescence Properties of Low-Dimensional Eu 3+-Activated Y 4Al 2O 9 Phosphor Compared to Bulk for Solid-State Lighting Applications and Latent Fingerprint Detection-Based Forensic Applications. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2019; 25:1422-1430. [PMID: 31025617 DOI: 10.1017/s143192761900028x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In recent years, nanoscale phosphors have become vital in optoelectronic applications and to understand the improved performance of nanophosphors over bulk material, detailed investigation is essential. Herein, trivalent europium-activated Y4Al2O9 phosphors were developed by solid-state reaction and solvothermal reaction methods and their performance as a function of their dimension was studied for various applications. Under 394 nm optical excitation, the photoluminescence (PL) emission, excited state lifetime of the nanophosphor, exhibits greater performance than its bulk counterpart. The homogeneous spherical structure of the nanophosphors as compared with solid lumps of bulk phosphors is the basis for almost 40% of the enhancement in nanophosphors' intense red emission compared to the bulk. Moreover, the thermal stability of the nanophosphor is much better than the bulk phosphor, which clearly indicates a key advantage of nanophosphor. The superior performance of Eu3+-doped Y4Al2O9 nanophosphors over their bulk counterparts has been demonstrated for industrial phosphor-converted light-emitting diodes and visualization of latent fingerprint.
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Affiliation(s)
- Antika Das
- School of Materials Science and Nanotechnology, Jadavpur University, Kolkata-700032, West Bengal, India
| | - Subhajit Saha
- School of Materials Science and Nanotechnology, Jadavpur University, Kolkata-700032, West Bengal, India
| | - Karamjyoti Panigrahi
- School of Materials Science and Nanotechnology, Jadavpur University, Kolkata-700032, West Bengal, India
| | - Uttam Kumar Ghorai
- Department of Industrial Chemistry and Applied Chemistry, Swami Vivekananda Research Centre, Ramakrishna Mission Vidyamandira, Belurmath, Howrah-711202, West Bengal, India
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Walenta CA, Tschurl M, Heiz U. Introducing catalysis in photocatalysis: What can be understood from surface science studies of alcohol photoreforming on TiO 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:473002. [PMID: 31342942 DOI: 10.1088/1361-648x/ab351a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Mechanisms in heterogeneous photocatalysis have traditionally been interpreted by the band-structure model and analogously to electrochemistry. This has led to the establishment of 'band-engineering' as a leading principle for the discovery of more efficient photocatalysts. In such a picture, mainly thermodynamic aspects are taken into account, while kinetics are often ignored. This holds in particular for chemical kinetics, which are, other than those for charge carrier dynamics, often not at all considered for the interpretation of the catalysts' photocatalytic performance. However, while being usually neglected in photocatalyis, they are a traditional and powerful tool in thermal catalysis and are still applied with great success in this field. While surface science studies made substantial contributes to thermal catalysis, analogous studies in heterogeneous photocatalysis still play only a minor role. In this review, the authors show that the photo-physics of defined materials in well-defined environments can be correlated with photochemical events on a surface, highlighting the importance of well-characterized semiconductors for the interpretation of mechanisms in heterogeneous photochemistry. The work focuses on contributions from surface science, which were obtained for the model system of a titania single crystal and alcohol photo-reforming. It is demonstrated that only surface science studies have so far enabled the elucidation of molecularly precise reaction mechanisms, the determination of reaction intermediates and assignment of reactive sites. As the identification of these properties remain major prerequisites for a breakthrough in photocatalysis research, the work also discusses the implications of the findings for applied systems. In general, the results from surface science demonstrate that photocatalytic systems shall also be approached by a perspective originating from heterogeneous catalysis rather than solely from an electrochemical point of view.
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Wei Z, Endo-Kimura M, Wang K, Colbeau-Justin C, Kowalska E. Influence of Semiconductor Morphology on Photocatalytic Activity of Plasmonic Photocatalysts: Titanate Nanowires and Octahedral Anatase Nanoparticles. NANOMATERIALS 2019; 9:nano9101447. [PMID: 31614677 PMCID: PMC6835321 DOI: 10.3390/nano9101447] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/04/2019] [Accepted: 10/04/2019] [Indexed: 02/07/2023]
Abstract
Octahedral anatase particles (OAP) with eight exposed and thermodynamically most stable (101) facets were prepared by an ultrasonication-hydrothermal (US-HT) reaction from potassium titanate nanowires (TNW). The precursor (TNW) and the product (OAP) of US-HT reaction were modified with nanoparticles of noble metals (Au, Ag or Pt) by photodeposition. Samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), scanning transmission electron microscopy (STEM) and time-resolved microwave conductivity (TRMC). The photocatalytic activity was investigated in three reaction systems, i.e., anaerobic dehydrogenation of methanol and oxidative decomposition of acetic acid under UV/vis irradiation, and oxidation of 2-propanol under vis irradiation. It was found that hydrogen liberation correlated with work function of metals, and thus the most active were platinum-modified samples. Photocatalytic activities of bare and modified OAP samples were much higher than those of TNW samples, probably due to anatase presence, higher crystallinity and electron mobility in faceted NPs. Interestingly, noble metals showed different influence on the activity depending on the semiconductor support, i.e., gold-modified TNW and platinum-modified OAP exhibited the highest activity for acetic acid decomposition, whereas silver- and gold-modified samples were the most active under vis irradiation, respectively. It is proposed that the form of noble metal (metallic vs. oxidized) as well as the morphology (well-organized vs. uncontrolled) have a critical effect on the overall photocatalytic performance. TRMC analysis confirmed that fast electron transfer to noble metal is a key factor for UV activity. It is proposed that the efficiency of plasmonic photocatalysis (under vis irradiation) depends on the oxidation form of metal (zero-valent preferable), photoabsorption properties (broad localized surface plasmon resonance (LSPR)), kind of metal (silver) and counteraction of “hot” electrons back transfer to noble metal NPs (by controlled morphology and high crystallinity).
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Affiliation(s)
- Zhishun Wei
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China.
- Institute for Catalysis (ICAT), Hokkaido University, N21 W10, Sapporo 001-0021, Japan.
| | - Maya Endo-Kimura
- Institute for Catalysis (ICAT), Hokkaido University, N21 W10, Sapporo 001-0021, Japan.
| | - Kunlei Wang
- Institute for Catalysis (ICAT), Hokkaido University, N21 W10, Sapporo 001-0021, Japan.
| | | | - Ewa Kowalska
- Institute for Catalysis (ICAT), Hokkaido University, N21 W10, Sapporo 001-0021, Japan.
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34
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Maitani MM, Tateyama A, Boix PP, Han G, Nitta A, Ohtani B, Mathews N, Wada Y. Effects of energetics with {001} facet-dominant anatase TiO2 scaffold on electron transport in CH3NH3PbI3 perovskite solar cells. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.01.102] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Parrino F, De Pasquale C, Palmisano L. Influence of Surface-Related Phenomena on Mechanism, Selectivity, and Conversion of TiO 2 -Induced Photocatalytic Reactions. CHEMSUSCHEM 2019; 12:589-602. [PMID: 30387918 DOI: 10.1002/cssc.201801898] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 09/28/2018] [Indexed: 06/08/2023]
Abstract
Heterogeneous photocatalysis is the result of an inextricable connection of several factors differently contributing to the overall process. Photon absorption is the "sine qua non" condition for the reaction to occur. In fact, photons can be considered as immaterial reactants, and all of the phenomena related to the interaction of light-matter play a prominent role. However, other factors contribute in a concerted way to address the reaction, so that the relative contribution of each of them is often difficult to evaluate. In this framework, the present paper highlights some aspects of the interaction of TiO2 surface-adsorbate species that could be underestimated and their influence on the conversion, selectivity, and mechanisms of photocatalytic reactions. To this aim, some paradigmatic examples on the adsorption of water and organics on TiO2 are reported.
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Affiliation(s)
- Francesco Parrino
- Dipartimento di Scienze Agrarie, Alimentari e Forestali, Università degli Studi di Palermo, viale delle Scienze 8, 90128, Palermo, Italy
- Dipartimento di Energia, Ingegneria dell'informazione e Modelli Matematici (DEIM), Università degli Studi di Palermo, viale delle Scienze Ed. 6, 90128, Palermo, Italy
- Dipartimento di Ingegneria Industriale (DII), Università di Trento, via Sommarive 9, 38123, Trento, Italy
| | - Claudio De Pasquale
- Dipartimento di Scienze Agrarie, Alimentari e Forestali, Università degli Studi di Palermo, viale delle Scienze 8, 90128, Palermo, Italy
| | - Leonardo Palmisano
- Dipartimento di Energia, Ingegneria dell'informazione e Modelli Matematici (DEIM), Università degli Studi di Palermo, viale delle Scienze Ed. 6, 90128, Palermo, Italy
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36
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Identification and characterization of titania photocatalyst powders using their energy-resolved distribution of electron traps as a fingerprint. Catal Today 2019. [DOI: 10.1016/j.cattod.2017.12.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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37
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Wei Z, Janczarek M, Endo M, Wang K, Balčytis A, Nitta A, Méndez-Medrano MG, Colbeau-Justin C, Juodkazis S, Ohtani B, Kowalska E. Noble metal-modified faceted anatase titania photocatalysts: Octahedron versus decahedron. APPLIED CATALYSIS. B, ENVIRONMENTAL 2018; 237:574-587. [PMID: 30532348 PMCID: PMC6100264 DOI: 10.1016/j.apcatb.2018.06.027] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/03/2018] [Accepted: 06/09/2018] [Indexed: 05/23/2023]
Abstract
Octahedral anatase particles (OAP, with eight equivalent {101} facets) and decahedral anatase particles (DAP, with two additional {001} facets) were modified with nanoparticles of noble metals (Au, Ag, Cu). The titania morphology, expressed by the presence of different arrangements of exposed crystal facets, played a key role in the photocatalytic properties of metal-modified faceted titania. In the UV/vis systems, two-faceted configuration of DAP was more favorable for the reaction efficiency than single-faceted OAP because of an efficient charge separation described by the transfer of electrons to {101} facets and holes to {001} facets. Time-resolved microwave conductivity (TRMC) and reversed double-beam photoacoustic spectroscopy (RDB-PAS) confirmed that distribution of electron traps (ET) and mobility of electrons were key-factors of photocatalytic activity. In contrast, metal-modified OAP samples had higher photocatalytic activity than metal-modified DAP and metal-modified commercial titania samples under visible light irradiation. This indicates that the presence of single type of facets ({101}) is favorable for efficient electron transfer via shallow ET, whereas intrinsic properties of DAP result in fast charge carriers' recombination when gold is deposited on {101} facets (migration of "hot" electrons: Au→{101}→Au).
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Affiliation(s)
- Zhishun Wei
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan, 430068, China
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| | - Marcin Janczarek
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
- Department of Chemical Technology, Gdansk University of Technology, G. Narutowicza 11/12, 80-233, Gdansk, Poland
| | - Maya Endo
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| | - Kunlei Wang
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| | - Armandas Balčytis
- Center for Micro-Photonics, Swinburne University of Technology, John St., Hawthorn, 3122 Vic, Australia
| | - Akio Nitta
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| | - Maria G. Méndez-Medrano
- Laboratory of Physical Chemistry, UMR 8000, University of Paris-Saclay, 91405, Orsay, France
| | | | - Saulius Juodkazis
- Center for Micro-Photonics, Swinburne University of Technology, John St., Hawthorn, 3122 Vic, Australia
| | - Bunsho Ohtani
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
| | - Ewa Kowalska
- Institute for Catalysis, Hokkaido University, N21, W8, 001-0021, Sapporo, Japan
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OHTANI B. Physicochemical Mechanistic Studies on Photocatalysis–Extension of Semiconductor Photoelectrochemistry Concept beyond Its Limitation. ELECTROCHEMISTRY 2018. [DOI: 10.5796/electrochemistry.18-6-e2667] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Miyasato R, Fujiwara M, Sato H, Yano T, Hashimoto H. Correlation between surface carrier dynamics and water oxidation activity of commercially available rutile-type TiO2 powders. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2018.09.063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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40
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Murakami N, Shinoda T. Mid-infrared absorption of trapped electrons in titanium(iv) oxide particles using a photoacoustic FTIR technique. Phys Chem Chem Phys 2018; 20:24519-24522. [PMID: 30226232 DOI: 10.1039/c8cp04885a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mid-infrared absorption of titanium(iv) oxide (TiO2) under ultraviolet (UV) irradiation was studied by Fourier transform infrared spectroscopy using a photoacoustic (PA) technique. UV irradiation induced an upward shift of the PA spectra, which is due to the trivalent titanium (Ti3+) species produced by electron accumulation. The PA spectra under UV irradiation mainly depend on the crystal structure, indicating that the energy levels of Ti3+ are largely determined by crystal structures.
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Affiliation(s)
- Naoya Murakami
- Department of Applied Chemistry, Faculty of Engineering, Kyushu Institute of Technology, 1-1 Sensuicho, Tobata, Kitakyushu 804-8550, Japan.
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Kobielusz M, Pilarczyk K, Świętek E, Szaciłowski K, Macyk W. Spectroelectrochemical analysis of TiO 2 electronic states – Implications for the photocatalytic activity of anatase and rutile. Catal Today 2018. [DOI: 10.1016/j.cattod.2017.11.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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42
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Influence of an Electronic Structure of N-TiO2 on Its Photocatalytic Activity towards Decomposition of Acetaldehyde under UV and Fluorescent Lamps Irradiation. Catalysts 2018. [DOI: 10.3390/catal8020085] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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43
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Nitta A, Takashima M, Murakami N, Takase M, Ohtani B. Reversed double-beam photoacoustic spectroscopy of metal-oxide powders for estimation of their energy-resolved distribution of electron traps and electronic-band structure. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2017.12.160] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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44
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45
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Chamtouri M, Kenens B, Aubert R, Lu G, Inose T, Fujita Y, Masuhara A, Hofkens J, Uji-i H. Facet-Dependent Diol-Induced Density of States of Anatase TiO 2 Crystal Surface. ACS OMEGA 2017; 2:4032-4038. [PMID: 28782054 PMCID: PMC5537687 DOI: 10.1021/acsomega.6b00473] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 06/21/2017] [Indexed: 05/13/2023]
Abstract
Owing to their fundamental importance and practical applications, anatase TiO2 crystals with well-defined {001} and {101} facets attracted intensive research interests. In this study, we systematically investigated solvent dependence of the photoreaction of the different coexposed crystal facets during noble metal photodeposition. By examining the deposition position in each solvent, we revealed that solvents play a pivotal role on the facet selectivity. On the basis of density functional theory calculations, the solvent molecules were found to modify both the crystal facet electronic structure and the {001}-{001} heterojunction. These modifications are not only the origin of diverse charge-carrier pathways but are also responsible for carrier accumulation at specific facets that increase their reductive power. These findings are vital for a better understanding of photocatalytic materials and an improved design for the next-generation materials.
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Affiliation(s)
- Maha Chamtouri
- Department
of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Heverlee, Belgium
| | - Bart Kenens
- Department
of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Heverlee, Belgium
| | - Remko Aubert
- Department
of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Heverlee, Belgium
| | - Gang Lu
- Department
of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Heverlee, Belgium
- Nanjing
Tech University, KLOFE, SICAM, 30 South Puzhu Road, Nanjing 211816, Jiangsu, People’s Republic of China
| | - Tomoko Inose
- RIES, Hokkaido University, N20W10, Kita-Ward Sapporo 001-0020, Japan
| | - Yasuhiko Fujita
- Department
of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Heverlee, Belgium
| | - Akito Masuhara
- Graduate
School of Science and Engineering, Yamagata
University, 4-13-16, Jonan, Yonezawa 992-8510, Japan
| | - Johan Hofkens
- Department
of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Heverlee, Belgium
- RIES, Hokkaido University, N20W10, Kita-Ward Sapporo 001-0020, Japan
| | - Hiroshi Uji-i
- Department
of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Heverlee, Belgium
- RIES, Hokkaido University, N20W10, Kita-Ward Sapporo 001-0020, Japan
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Hidden but Possibly Fatal Misconceptions in Photocatalysis Studies: A Short Critical Review. Catalysts 2016. [DOI: 10.3390/catal6120192] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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