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Huang X, Yang G. Enhanced immobilization of Arsenic(III) and Auto-oxidation to Arsenic(V) by titanium oxide (TiO 2), due to Single-Atom vacancies and oxyanion formation. J Colloid Interface Sci 2023; 650:1327-1338. [PMID: 37478750 DOI: 10.1016/j.jcis.2023.07.103] [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: 04/11/2023] [Revised: 06/28/2023] [Accepted: 07/16/2023] [Indexed: 07/23/2023]
Abstract
Pollution control of As(III), a naturally occurring carcinogen, has recently gained a global attention, while due to the dominance of neutral H3AsO3 over a wide pH range, As(III) immobilization by most minerals is not efficient as As(V) immobilization. TiO2 shows promise for controlling As(III) pollution, and herein, a comprehensive study about As(III) adsorption by TiO2 and oxyanion formation is conducted by means of DFT + D3 methods. Both anatase and rutile are effective for As(III) adsorption, while As(III) adsorption affinities differ significantly and are -1.48 and -3.79 eV for pristine surfaces, ascend to -3.85 and -5.08 eV for O vacancies, and further to -5.37 and -5.26 eV for Ti vacancies, respectively. The bidentate binuclear complexes dominate for pristine surfaces, and O vacancies prefer OAs insertion into TiO2 lattice, while for Ti vacancies, all As(III) centers are auto-oxidized to As(V). Ti-3d, O-2p or/and As-4p rather than other orbitals contribute significantly to As adsorption, and O and Ti vacancies promote adsorption through stronger orbital hybridization. The superior adsorption for Ti vacancies originates from As(V) formation instead of bonding interactions. The formation of As oxyanions, which may occur spontaneously at pristine surfaces and is greatly promoted by O and Ti vacancies, enhances As(III) adsorption pronouncedly and becomes a viable strategy for As(III) immobilization. H2AsO3- and HAsO32- dominate for pristine surfaces and O vacancies, and for Ti vacancies, H2AsO4- and HAsO42- dominate over anatase whereas AsO43- also makes an important contribution over rutile. Results rationalize experimental observations available, and provide significantly new insights about the migration, bioavailability and fate of As(III) over TiO2 surfaces that facilitate the exploration of scavengers for As and other pollutants.
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Affiliation(s)
- Xiaoxiao Huang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Gang Yang
- College of Resources and Environment, Southwest University, Chongqing 400715, China.
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Yang F, Zhang L, Li F, Zhang Z, Cui L, Li R, Fan C, Liu J. Enhanced photocatalytic hydrogen evolution of Ru/TiO 2-x via oxygen vacancy-assisted hydrogen spillover process. J Colloid Interface Sci 2023; 650:294-303. [PMID: 37413863 DOI: 10.1016/j.jcis.2023.06.206] [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: 04/13/2023] [Revised: 06/23/2023] [Accepted: 06/30/2023] [Indexed: 07/08/2023]
Abstract
Hydrogen spillover effects will significantly improve the activity of photocatalytic hydrogen evolution reactions (HER), while their introduction and optimization require the construction of an excellent metal/support structure. In this study, we have synthesized Ru/TiO2-x catalysts with controlled oxygen vacancy (OVs) concentrations using a simple one-pot solvothermal method. The results show that Ru/TiO2-x3 with the optimal OVs concentration exhibits an unprecedentedly high H2 evolution rate of 13604 μmol·g-1·h-1, which was 45.7 and 2.2 times higher than that of TiO2-x (298 μmol·g-1·h-1) and Ru/TiO2 (6081 μmol·g-1·h-1). Controlled experiments, detailed characterizations, and theoretical calculations have revealed that the introduction of OVs on the carrier contributes to the hydrogen spillover effect in the metal/support system photocatalyst and that the process of hydrogen spillover in this system can be optimized by modulating the OVs concentration. This study proposes a strategy to decrease the energy barrier of hydrogen spillover and enhance photocatalytic HER activity. Moreover, it investigates the effect of OVs concentration on the hydrogen spillover effect in the photocatalytic metal/supports system.
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Affiliation(s)
- Fan Yang
- College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, PR China
| | - Lulu Zhang
- College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, PR China
| | - Feifei Li
- College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, PR China
| | - Zhipeng Zhang
- College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, PR China
| | - Luyao Cui
- College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, PR China
| | - Rui Li
- College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, PR China; College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, PR China
| | - Caimei Fan
- College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, PR China
| | - Jianxin Liu
- College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, PR China.
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Li JQ, Hu JY, Cheng J. Water effect on the band edges of anatase TiO 2 surfaces: A theoretical study on charge migration across surface heterojunctions and facet-dependent photoactivity. Phys Chem Chem Phys 2023; 25:29143-29154. [PMID: 37869989 DOI: 10.1039/d3cp03662f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
The charge migration mechanism across the surface heterojunction constructed on an anatase TiO2 nanocrystal is still under debate. To solve this longstanding question, we present a systematic study of the band edges (vs. standard hydrogen electrode, SHE) of aqueous TiO2 interfaces with anatase (101), (100) and (001) surfaces, using a combination of density functional theory-based molecular dynamics (DFTMD) and efficient computational SHE (cSHE) methods. Our calculations show that the conduction band minimum (CBM) of the (101) surface is lower than that of (001) and (100) surfaces, which is thermodynamically favorable for electrons migrating to the (101) surface through the surface heterojunction, while the hole preferentially accumulates on the (100) surface due to its highest valence band minimum (VBM). In addition, we qualitatively explore the facet-dependent photocatalytic activity of anatase TiO2. Due to the possession of both the beneficial atomic structure (with 100% undercoordinated Ti5c atoms at the surface) and electronic structure (more strongly oxidizing holes in the VBM and efficient electron-hole spatial separation separation), the (001) surface exhibits the most efficient photocatalytic performance for water oxidation. Furthermore, it is confirmed that the use of simplified theoretical models neglecting the detailed atomic structures of water at the aqueous interface is inadequate to predict the band alignment of semiconductors relative to water redox potentials, so that it may result in substantial errors in evaluating the photocatalytic performance of materials to be used for water splitting.
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Affiliation(s)
- Jie-Qiong Li
- State Henan Engineering Center of New Energy Battery Materials, Henan D&A Engineering Center of Advanced Battery Materials, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000, China.
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Jin-Yuan Hu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Jun Cheng
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
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Dong Z, Hu S, Li Z, Xu J, Gao D, Yu F, Li X, Cao X, Wang Y, Zhang Z, Liu Y, Wang X. Biomimetic Photocatalytic System Designed by Spatially Separated Cocatalysts on Z-scheme Heterojunction with Identified Charge-transfer Processes for Boosting Removal of U(VI). SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300003. [PMID: 36807523 DOI: 10.1002/smll.202300003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 01/30/2023] [Indexed: 05/18/2023]
Abstract
Designing highly efficient photocatalysts with rapid migration of photogenerated charges and surface reaction kinetics for the photocatalytic removal of uranium (U(VI)) from uranium mine wastewater remains a significant challenge. Inspired by natural photosynthesis, a biomimetic photocatalytic system is assembled by designing a novel hollow nanosphere MnOx @TiO2 @CdS@Au (MTCA) with loading MnOx and Au nano particles (Au NPs) cocatalysts on the inner and outer surfaces of the TiO2 @CdS. The spatially separated cocatalysts efficiently drive the photogenerated charges to migrate in opposite directions, while the Z-scheme heterogeneous shell further separates the interfacial charges. Theoretical calculation identifies multiple consecutive forward charge transfers without charge recombination within MTCA. Thus, MTCA could efficiently remove 99.61% of U(VI) after 15 min of simulated sunlight irradiation within 3 mmol L-1 NaHCO3 with 0.231 min-1 of the reduction rate constant, outperforming most previously reported photocatalysts. MTCA further significantly removes 91.83% of U(VI) from the natural uranium mining wastewater under sunlight irradiation. This study provides a novel approach to designing an ideal biomimetic photocatalyst for remediating environmental pollution.
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Affiliation(s)
- Zhimin Dong
- State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang, 330013, P. R. China
- Institute of Geology, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, 100037, Beijing, P. R. China
| | - Shuxian Hu
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Zifan Li
- State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang, 330013, P. R. China
| | - Jinhao Xu
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Donglin Gao
- State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang, 330013, P. R. China
| | - Fengtao Yu
- State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang, 330013, P. R. China
| | - Xiaoyan Li
- State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang, 330013, P. R. China
| | - Xiaohong Cao
- State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang, 330013, P. R. China
| | - Youqun Wang
- State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang, 330013, P. R. China
| | - Zhibin Zhang
- State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang, 330013, P. R. China
| | - Yunhai Liu
- State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang, 330013, P. R. China
| | - Xiangke Wang
- MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, P. R. China
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Khaja Hussain S, Bang JH. Overview of the oxygen vacancy effect in bimetallic spinel and perovskite oxide electrode materials for high-performance supercapacitors. Phys Chem Chem Phys 2023; 25:11892-11907. [PMID: 37097013 DOI: 10.1039/d3cp00472d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
Bimetallic spinel and perovskite metal oxide materials are advanced electrode materials for supercapacitor (SC) applications because of their low-cost, distinct crystal structures, eco-friendly nature, and high conductivity. However, they suffer from the disadvantages of poor ion-diffusion kinetics and pulverization issues during cyclability tests. Along with a deeper understanding of redox chemistry, the role of oxygen vacancies (OVs) in electrode materials to support the reaction kinetics for excellence in SCs must be clarified. In this review, we highlight for the first time the importance of OVs and summarize various design strategies for the preparation of advanced bimetallic spinel oxides and perovskites with improved electrochemical performances for SC applications. With new insights, we envision that the SC research community would endeavor to utilize the benefits of OVs effectively for the development of high-performance SCs.
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Affiliation(s)
- Sk Khaja Hussain
- Nanosensor Research Institute, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea.
| | - Jin Ho Bang
- Nanosensor Research Institute, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea.
- Department of Chemical and Molecular Engineering, Hanyang University, Ansan, Gyeonggi-do 15588, Republic of Korea
- Department of Applied Chemistry, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan, Gyeonggi-do 15588, Republic of Korea
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Nitrogen-Doped Titanium Dioxide as a Hole Transport Layer for High-Efficiency Formamidinium Perovskite Solar Cells. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27227927. [PMID: 36432027 PMCID: PMC9694249 DOI: 10.3390/molecules27227927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/02/2022] [Accepted: 11/14/2022] [Indexed: 11/18/2022]
Abstract
Perovskite solar cells (PSCs) offer advantages over widely deployed silicon solar cells in terms of ease of fabrication; however, the device is still under rigorous materials optimization for cell performance, stability, and cost. In this work, we explore a version of a PSC by replacing the polymeric hole transport layer (HTL) such as Spiro-OMeTAD, P3HT, and PEDOT: PSS with a more air-stable metal oxide, viz., nitrogen-doped titanium dioxide (TiO2:N). Numerical simulations on formamidinium (FA)-based PSCs in the FTO/TiO2/FAPbI3/Ag configuration have been carried out to depict the behaviour of the HTL as well as the effect of absorber layer thickness (∆t) on photovoltaic parameters. The results show that the cell output increases when the HTL bandgap increases from 2.5 to 3.0 eV. By optimizing the absorber layer thickness and the gradient in defect density (Nt), the device structure considered here can deliver a maximum power conversion efficiency of ~21.38% for a lower HTL bandgap (~2.5 eV) and ~26.99% for a higher HTL bandgap of ~3.0 eV. The results are validated by reproducing the performance of PSCs employing commonly used polymeric HTLs, viz. Spiro-OMeTAD, P3HT, and PEDOT: PSS as well as high power conversion efficiency in the highly crystalline perovskite layer. Therefore, the present study provides high-performing, cost-effective PSCs using TiO2:N.
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Sun F, Xu D, Xie Y, Liu F, Wang W, Shao H, Ma Q, Yu H, Yu W, Dong X. Tri-functional aerogel photocatalyst with an S-scheme heterojunction for the efficient removal of dyes and antibiotic and hydrogen generation. J Colloid Interface Sci 2022; 628:614-626. [PMID: 36027772 DOI: 10.1016/j.jcis.2022.08.089] [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: 06/19/2022] [Revised: 08/10/2022] [Accepted: 08/13/2022] [Indexed: 10/15/2022]
Abstract
A novel three-dimensional (3D) S-scheme S-gC3N4/TiO2/SiO2/PAN aerogel heterojunction photocatalyst (denoted as S-gTAHP) is rationally devised and manufactured by combining electrospinning, calcination, hydrothermal and freeze-drying techniques. The synthesized S-gC3N4 molecule is different from traditional g-C3N4, which has a small molecular structure similar to melamine. S-gC3N4 is embedded in the interwoven network structure of TiO2/PAN short fibers, and the catalytic system of the S-scheme heterojunction is formed with SiO2 as a crosslinking agent. S-gTAHP achieves perfect tri-functional photocatalytic capability, including remarkable hydrogen release capacity (806.7 μmol∙h-1∙g-1), efficient removal of three colored dyes with removal efficiencies up to 99.43% (MB, 15 min), 96.13% (RhB, 30 min) and 91.32% (MO, 40 min), and a degradation rate of the colorless antibiotic TCH reaching 84.20% in 40 min driven by simulated sunlight. Meanwhile, the effects of pH values and concentrations of contaminant solutions on the removal rates are explored, and the S-scheme mechanism of S-gTAHP strengthening photocatalytic activity is elucidated. The apparently heightened photocatalytic activities of S-gTAHP can be ascribed to the fact that the 3D hierarchical porous structure of the aerogel endows more active centers and enhanced light-harvesting capacity, and the S-scheme heterojunction supplies effective charge migrating channels, thereby affording the carriers with strong redox capability. Furthermore, S-gTAHP holds prominent reusability and is light weight. Hence, efficient and recyclable 3D aerogel photocatalysts with S-scheme heterojunctions have broad application prospects in practical sewage treatment and energy conversion fields.
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Affiliation(s)
- Feng Sun
- College of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China; Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China
| | - Da Xu
- College of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China; Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China
| | - Yunrui Xie
- Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China
| | - Feng Liu
- College of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China; Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China
| | - Wenling Wang
- Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China
| | - Hong Shao
- Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China
| | - Qianli Ma
- Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China
| | - Hui Yu
- Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China
| | - Wensheng Yu
- Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China
| | - Xiangting Dong
- College of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China; Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun 130022, China.
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Wang K, Molteni C, Haynes PD. Localized Soft Vibrational Modes and Coherent Structural Phase Transformations in Rutile TiO 2 Nanoparticles under Negative Pressure. NANO LETTERS 2022; 22:5922-5928. [PMID: 35797495 PMCID: PMC9335867 DOI: 10.1021/acs.nanolett.2c01939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We study the effect of size on the vibrational modes and frequencies of nanoparticles, by applying a newly developed, robust, and efficient first-principles-based method that we present in outline. We focus on rutile TiO2, a technologically important material whose bulk exhibits a softening of a transverse acoustic mode close to q=(12,12,14), which becomes unstable with the application of negative pressure. We demonstrate that, under these conditions, nanoparticles above a critical size exhibit unstable localized modes and we calculate their characteristic localization length and decomposition with respect to bulk phonons. We propose that such localized soft modes could initiate coherent structural phase transformations in small nanoparticles above a critical size.
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Affiliation(s)
- Kang Wang
- Imperial
College London, Department of Materials, Exhibition Road, London SW7 2AZ, U.K.
| | - Carla Molteni
- King’s
College London, Department of Physics, Strand, London WC2R 2LS, U.K.
| | - Peter D. Haynes
- Imperial
College London, Department of Materials, Exhibition Road, London SW7 2AZ, U.K.
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