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Creation of Interfacial S 4 -Sn-N 2 Electron Pathways for Efficient Light-Driven Hydrogen Evolution. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2310664. [PMID: 38342707 DOI: 10.1002/smll.202310664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/28/2024] [Indexed: 02/13/2024]
Abstract
Establishing effective charge transfer channels between two semiconductors is key to improving photocatalytic activity. However, controlling hetero-structures in situ and designing binding modes pose significant challenges. Herein, hydrolytic SnCl2 ·2H2 O is selected as the metal source and loaded in situ onto a layered carbon nitriden supramolecular precursor. A composite photocatalyst, S4 -Sn-N2 , with electron pathways of SnS2 and tubular carbon nitriden (TCN) is prepared through pyrolysis and vulcanization processes. The contact interface of SnS2 -TCN is increased significantly, promoting the formation of S4 -Sn-N2 micro-structure in a Z-scheme charge transfer channel. This structure accelerates the separation and transport of photogenerated carriers, maintains the stronger redox ability, and improves the stability of SnS2 in this series of heterojunctions. Therefore, the catalyst demonstrated exceptional photocatalytic hydrogen production efficiency, achieving a reaction rate of 86.4 µmol h-1 , which is 3.15 times greater than that of bare TCN.
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Porous In 2O 3 Hollow Tube Infused with g-C 3N 4 for CO 2 Photocatalytic Reduction. ACS APPLIED MATERIALS & INTERFACES 2024; 16:4581-4591. [PMID: 38232351 DOI: 10.1021/acsami.3c14826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Converting CO2 into energy-rich fuels by using solar energy is a sustainable solution that promotes a carbon-neutral economy and mitigates our reliance on fossil fuels. However, affordable and efficient CO2 conversion remains an ongoing challenge. Here, we introduce polymeric g-C3N4 into the pores of a hollow In2O3 microtube. This architecture results in a compact and staggered arrangement between g-C3N4 and In2O3 components with an increased contact interface for improved charge separation. The hollow interior further contributes to strengthening light absorption. The resulting g-C3N4-In2O3 hollow tubes exhibit superior activity (274 μmol·g-1·h-1) toward CO2 to CO conversion in comparison with those of pure In2O3 and g-C3N4 (5.5 and 93.6 μmol·g-1·h-1, respectively), underlining the role of integrating g-C3N4 and In2O3 in this advanced system. This work offers a strategy for the advanced design and preparation of hollow heterostructures for optimizing CO2 adsorption and conversion by integrating inorganic and organic semiconductors.
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Light-Driven CO 2 Reduction with a Surface-Displayed Enzyme Cascade-C 3N 4 Hybrid. ACS Synth Biol 2023; 12:2715-2724. [PMID: 37651305 DOI: 10.1021/acssynbio.3c00273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Efficient and cost-effective conversion of CO2 to biomass holds the potential to address the climate crisis. Light-driven CO2 conversion can be realized by combining inorganic semiconductors with enzymes or cells. However, designing enzyme cascades for converting CO2 to multicarbon compounds is challenging, and inorganic semiconductors often possess cytotoxicity. Therefore, there is a critical need for a straightforward semiconductor biohybrid system for CO2 conversion. Here, we used a visible-light-responsive and biocompatible C3N4 porous nanosheet, decorated with formate dehydrogenase, formaldehyde dehydrogenase, and alcohol dehydrogenase to establish an enzyme-photocoupled catalytic system, which showed a remarkable CO2-to-methanol conversion efficiency with an apparent quantum efficiency of 2.48% in the absence of externally added electron mediator. To further enable the in situ transformation of methanol into biomass, the enzymes were displayed on the surface of Komagataella phaffii, which was further coupled with C3N4 to create an organic semiconductor-enzyme-cell hybrid system. Methanol was produced through enzyme-photocoupled CO2 reduction, achieving a rate of 4.07 mg/(L·h), comparable with reported rates from photocatalytic systems employing mediators or photoelectrochemical cells. The produced methanol can subsequently be transported into the cell and converted into biomass. This work presents a sustainable, environmentally friendly, and cost-effective enzyme-photocoupled biocatalytic system for efficient solar-driven conversion of CO2 within a microbial cell.
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Characterization and photocatalytic activity of CoCr 2O 4/g-C 3N 4 nanocomposite for water treatment. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023:10.1007/s11356-023-27807-3. [PMID: 37233934 DOI: 10.1007/s11356-023-27807-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 05/16/2023] [Indexed: 05/27/2023]
Abstract
One of the materials that has recently been used to remove environmental pollution from industrial effluents with photocatalytic technology is cobalt chromate (CoCr2O4) nanoparticles. An effective way to improve the photocatalytic properties of materials is to composite them with other photocatalysts to prevent recombination of electron-holes and accelerate the transfer of oxidation/reduction agents. Graphitic carbon nitride (g-C3N4) is an excellent choice due to its unique properties. In this research, CoCr2O4 and its composite with g-C3N4 (5, 10, and 15%) were synthesized by polyacrylamide gel method and characterized by X-ray diffraction, scanning electron microscopy, FTIR, UV-Vis spectroscopy techniques. The photocatalytic behavior of synthesized nanoparticles was investigated in the degradation process of methylene blue dye. The results showed that the composite samples have higher efficiency in photocatalytic activity than the pure CoCr2O4 sample. Using CoCr2O4-15 wt%g-C3N4 nanocomposite, after 80 min, methylene blue was completely degraded. The mechanism of degradation by CoCr2O4-g-C3N4 nanocomposite was the superoxide radical produced by the reaction of electrons with oxygen absorbed on the catalyst surface, as well as optically produced holes directly.
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Band Edges Engineering of 2D/2D Heterostructures: The C 3 N 4 /Phosphorene Interface. Chemphyschem 2023; 24:e202200791. [PMID: 36399544 DOI: 10.1002/cphc.202200791] [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: 10/21/2022] [Revised: 11/14/2022] [Indexed: 11/19/2022]
Abstract
We investigate the interface between carbon nitride (C3 N4 ) and phosphorene nanosheets (P-ene) by means of Density Functional Theory (DFT) calculations. C3 N4 /P-ene composites have been recently obtained experimentally showing excellent photoactivity. Our results indicate that the formation of the interface is a favorable process driven by Van der Waals forces. The thickness of P-ene nanosheets determines the band edges offsets and the charge carriers' separation. The system is predicted to pass from a nearly type-II to a type-I junction when the thickness of P-ene increases, and the conduction band offset is particularly sensitive. Last, we apply the Transfer Matrix Method to estimate the efficiency for charge carriers' migration as a function of the P-ene thickness.
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MOF-Derived Defective Co 3O 4 Nanosheets in Carbon Nitride Nanocomposites for CO 2 Photoreduction and H 2 Production. ACS APPLIED MATERIALS & INTERFACES 2023; 15:6817-6830. [PMID: 36719032 DOI: 10.1021/acsami.2c19683] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
In photocatalysis, especially in CO2 reduction and H2 production, the development of multicomponent nanomaterials provides great opportunities to tune many critical parameters toward increased activity. This work reports the development of tunable organic/inorganic heterojunctions comprised of cobalt oxides (Co3O4) of varying morphology and modified carbon nitride (CN), targeting on optimizing their response under UV-visible irradiation. MOF structures were used as precursors for the synthesis of Co3O4. A facile solvothermal approach allowed the development of ultrathin two-dimensional (2D) Co3O4 nanosheets (Co3O4-NS). The optimized CN and Co3O4 structures were coupled forming heterojunctions, and the content of each part was optimized. Activity was significantly improved in the nanocomposites bearing Co3O4-NS compared with the corresponding bulk Co3O4/CN composites. Transient absorption spectroscopy revealed a 100-fold increase in charge carrier lifetime on Co3O4-NS sites in the composite compared with the bare Co3O4-NS. The improved photocatalytic activity in H2 production and CO2 reduction is linked with (a) the larger interface imposed from the matching 2D structure of Co3O4-NS and the planar surface of CN, (b) improvements in charge carrier lifetime, and (c) the enhanced CO2 adsorption. The study highlights the importance of MOF structures used as precursors in forming advanced materials and the stepwise functionalization of the individual parts in nanocomposites for the development of materials with superior activity.
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Multivalent Effect of Defect Engineered Ag 2S/g-C 3N 4 3D Porous Floating Catalyst with Enhanced Contaminant Removal Efficiency. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:1357. [PMID: 36674113 PMCID: PMC9859220 DOI: 10.3390/ijerph20021357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/07/2023] [Accepted: 01/09/2023] [Indexed: 06/17/2023]
Abstract
Chlorophenols, as a major environmental pollutant, enter water systems through industrial wastewater, agricultural runoff and chemical spills, and they are stable, persistent under natural conditions, and highly hazardous to water resources. The objective of this article is to prepare Ag2S-modified C3N4 three-dimensional network photocatalyst by calcination method to use photocatalysis as an efficient, safe, and environmentally friendly method to degrade chlorophenols. Ag2S/C3N4 has an excellent visible light absorption range, low band gap, effective separation of photogenerated charges, and active free radicals production, all of which make for the enhancement of photocatalytic degradation performance of the Ag2S/C3N4 system. Under the light irradiation (λ ≥ 420 nm), the photocatalytic degradation efficiency of 2,4,6-Trichlorophenol reach 95% within 150 min, and the stable photocatalytic degradation activity can still be maintained under different pH water environment and four degradation cycles. When Ag2S is loaded on ACNs, more photogenerated electrons are generated and subsequent reactions produce highly reactive groups such as •O2- and •OH that will originally be able to continuously attack TCP molecules to degrade pollutants. Therefore, this study shows that the photocatalyst provides a novel research approach for realizing the application in the field of pollutant degradation.
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Preparation of C 3N 4/montmorillonite composite photocatalyst for effective removal of organic pollutants. ENVIRONMENTAL TECHNOLOGY 2022; 43:1513-1521. [PMID: 33086988 DOI: 10.1080/09593330.2020.1841303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 10/16/2020] [Indexed: 06/11/2023]
Abstract
Due to the good photocatalytic performance, which ensures the decomposition of pollutants under light, g-C3N4 is considered as an ideal photocatalytic material. Montmorillonite has a high adsorption capacity and layered structure, which has positive effects on increasing the specific surface area of g-C3N4 and avoid its polymerization agglomeration. In this paper, montmorillonite was used as carrier for g-C3N4 to obtain a new photocatalytic composite g-C3N4/Mt. Then the morphological and (micro)structural properties were characterized. The well-characterized materials were evaluated for the photocatalytic activity in degradation of methylene blue and Bisphenol A. The effects of the mass fraction of g-C3N4, light irradiation time, and pollutant concentration on the photocatalytic performance of g-C3N4/Mt composites were studied. Under the optimal experimental plan, the rate of photocatalytic degradation can reach to 99.3% within 120 min. Through the MS spectrum, it can be found that methylene blue molecule were catalysed and degraded into many harmless substances with low-molecular weight. Finally, based on the obtained reaction products, the mechanism by which the pollutants are removed was proposed. This study provides a new strategy to improve the photocatalysis ability of g-C3N4, which is of great significance for a sustainable pollution treatment.
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Engineering Nitrogen Vacancy in Polymeric Carbon Nitride for Nitrate Electroreduction to Ammonia. ACS APPLIED MATERIALS & INTERFACES 2021; 13:54967-54973. [PMID: 34755508 DOI: 10.1021/acsami.1c15206] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Electrocatalytic nitrate reduction to ammonia is of great interest in terms of energy conservation and environmental protection. However, the development of abundant metal-free electrocatalysts with high activity, selectivity, and stability is still a big challenge. Herein, polymeric graphitic carbon nitride (g-C3N4) with controllable numbers of nitrogen vacancies is reported to exhibit high Faradaic efficiency (89.96%), selectivity (69.78%), and stability toward nitrate-to-ammonia conversion. 15N isotope labeling experiments prove the produced ammonia originating from nitrate reduction. The combined results of ex situ and in situ characterizations unveil the reaction pathway based on the captured critical intermediates. Density functional theory calculations reveal that nitrogen vacancies could introduce a new electron state at the Fermi level and promote the adsorption, activation, and dissociation of nitrate. An appropriate content of nitrogen vacancies is beneficial for modulating the adsorption energies of reaction intermediates (*NO, *NOH, *NH2, etc.), facilitating the enhancement in ammonia selectivity and Faradaic efficiency.
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Maximum Achievable N Content in Atom-by-Atom Growth of Amorphous Si-B-C-N Materials. MATERIALS (BASEL, SWITZERLAND) 2021; 14:5744. [PMID: 34640138 PMCID: PMC8510390 DOI: 10.3390/ma14195744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 11/16/2022]
Abstract
Amorphous Si-B-C-N alloys can combine exceptional oxidation resistance up to 1500 °C with high-temperature stability of superior functional properties. Because some of these characteristics require as high N content as possible, the maximum achievable N content in amorphous Si-B-C-N is examined by combining extensive ab initio molecular dynamics simulations with experimental data. The N content is limited by the formation of unbonded N2 molecules, which depends on the composition (most intensive in C rich materials, medium in B rich materials, least intensive in Si-rich materials) and on the density (increasing N2 formation with decreasing packing factor when the latter is below 0.28, at a higher slope of this increase at lower B content). The maximum content of N bonded in amorphous Si-B-C-N networks of lowest-energy densities is in the range from 34% to 57% (materials which can be grown without unbonded N2) or at most from 42% to 57% (at a cost of affecting materials characteristics by unbonded N2). The results are important for understanding the experimentally reported nitrogen contents, design of stable amorphous nitrides with optimized properties and pathways for their preparation, and identification of what is or is not possible to achieve in this field.
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2D Bismuthene Metal Electron Mediator Engineering Super Interfacial Charge Transfer for Efficient Photocatalytic Reduction of Carbon Dioxide. ACS APPLIED MATERIALS & INTERFACES 2021; 13:21582-21592. [PMID: 33934603 DOI: 10.1021/acsami.1c01470] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The interfacial charge transfer still limits the photoactivity of artificial Z-scheme photocatalysts although they showed complementary light absorption and a strong photoredox ability. In this study, layered metallene is designed as an efficient electron mediator for constructing a C3N4/bismuthene/BiOCl 2D/2D/2D Z-scheme system. This bismuthene serves as a bridge processing superior charge conductibility, abundant metal-semiconductor contact sites, and the shortened charge diffusion distance, enhancing the photocatalytic CO2 reduction reaction activity and stability. Density functional theory calculations show that the bismuthene creates a built-in electric field and congregates interfacial electrons, which is confirmed by the stable and consistent emission of the ultrafast transient absorption spectra. This work gives new insight into the interface design of Z-scheme photocatalysts by selecting a novel metallene electron mediator.
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Synthesis of coralloid carbon nitride polymers and photocatalytic selective oxidation of benzyl alcohol. NANOTECHNOLOGY 2021; 32:235602. [PMID: 33621964 DOI: 10.1088/1361-6528/abe903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/23/2021] [Indexed: 06/12/2023]
Abstract
Polymeric carbon nitride (C3N4) is currently the most potential nonmetallic photocatalyst, but it suffers from low catalytic activity due to rapid electron-hole recombination behavior and low specific surface area. The morphology control of C3N4is one of the effective methods used to achieve higher photocatalytic performance. Here, bulk, lamellar and coralloid C3N4were synthesized using different chemical methods. The as-prepared coralloid C3N4has a higher specific surface area (123.7 m2 · g-1) than bulk (5.4 m2 · g-1) and lamellar C3N4(2.8 m2 · g-1), thus exhibiting a 3.15- and 2.59-fold higher photocatalytic efficiency for the selective oxidation of benzyl alcohol than bulk and lamellar C3N4, respectively. Optical characterizations of the photocatalysts suggest that coralloid C3N4can effectively capture electrons and accelerate carrier separation, which is caused by the presence of more nitrogen vacancies. Furthermore, it is demonstrated that superoxide radicals (·O2-) and holes (h+) play major roles in the photocatalytic selective oxidation of benzyl alcohol using C3N4as a photocatalyst.
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In situ growth of carbon nitride on titanium dioxide/hemp stem biochar toward 2D heterostructured photocatalysts for highly photocatalytic activity. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:39198-39210. [PMID: 32638312 DOI: 10.1007/s11356-020-09381-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 05/19/2020] [Indexed: 06/11/2023]
Abstract
In this work, hierarchical structure TiO2/hemp stem biochar carbon (HSBC) and C3N4-TiO2/HSBC were successfully fabricated, which were used as efficient visible-light photocatalyst degradation for ammonia nitrogen from aqueous solution. The as-prepared C3N4-TiO2/HSBC hybrid catalyst showed the higher efficient photocatalytic activity for decomposition of ammonia nitrogen than those of pure TiO2 and TiO2/HSBC, suggesting suppressed recombination of photogenerated charges and promoted mass transfer due to synergistic effect, and thus increased photocatalytic degradation activity. The degradation of ammonia follows a pseudo-first-order kinetics. All prepared catalysts demonstrated extremely photocatalytic efficiency under visible-light and UV light illumination; the ammonia nitrogen photocatalytic degradation activity of C3N4-TiO2/HSBC can reach 90.3% under UV light while the degradation activity achieved about 50.7% under visible-light irradiation. The results revealed that the h+ was dominantly active intermediates in the process of photocatalytic degradation. The prepared catalysts are promising for the degradation of ammonia nitrogen from water resource.
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Maximum Achievable N Content in Atom-by-Atom Growth of Amorphous Si-C-N. ACS APPLIED MATERIALS & INTERFACES 2020; 12:41666-41673. [PMID: 32830493 DOI: 10.1021/acsami.0c08300] [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 maximum achievable N content in atom-by-atom growth of Si-C-N films is examined by combining ab initio molecular dynamics simulations in a wide range of compositions and densities with experimental data. When and only when the simulation algorithm allows the formation and final presence of N2 molecules, the densities leading to the deepest local energy minima are in agreement with the experiment. The main attention is paid to unbonded N2 molecules, with the aim to predict and explain the maximum content of N bonded in the amorphous networks. There are significant differences resulting from different compositions, ranging from no N2 at the lowest energy density of a-Si3N4 (57 atom % of bonded N) to many N2 at the lowest energy density of a-C3N4 (42 atom % of bonded N). The theoretical prediction is in agreement with the experimental results of reactive magnetron sputtering at varied Si+C sputter target compositions and N2 partial pressures. A detailed analysis reveals that while there is a relationship between the N2 formation and the packing factor, which is valid in the whole compositional range investigated, the lowest-energy packing factor depends on the composition. The results are important for the explanation of experimentally reported maximum N contents, design of technologically important amorphous nitrides and pathways of their preparation, prediction of their stability, and identification of what may or may not be achieved in this field.
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Photocatalytic Performance and Degradation Pathway of Rhodamine B with TS-1/C 3N 4 Composite under Visible Light. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E756. [PMID: 32326608 PMCID: PMC7221997 DOI: 10.3390/nano10040756] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 04/08/2020] [Accepted: 04/13/2020] [Indexed: 11/16/2022]
Abstract
TS-1/C3N4 composites were prepared by calcining the precursors with cooling crystallization method and were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), UV-Vis diffuse reflection spectrum (DRS) and nitrogen adsorption-desorption isotherm. The photocatalytic performance of TS-1/C3N4 composites was investigated to degrade Rhodamine B (RhB) under visible light irradiation. The results showed that all composites exhibited better photocatalytic performance than pristine TS-1 and C3N4; TS-1/C3N4-B composite (the measured mass ratio of TS-1 to C3N4 is 1:4) had best performance, with a rate constant of 0.04166 min-1, which is about two and ten times higher than those of C3N4 and TS-1, respectively. We attributed the enhanced photocatalytic performance of TC-B to the optimized heterostructure formed by TS-1 and C3N4 with proper proportion. From the results of photoluminescence spectra (PL) and the enhanced photocurrent, it is concluded that photogenerated electrons and holes were separated more effectively in TS-1/C3N4 composites. The contribution of the three main active species for photocatalytic degradation followed a decreasing order of ·O2-, ·OH and h+. The degradation products of RhB were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS), and the possible photocatalytic degradation pathways were proposed.
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Design of C 3 N 4 -Based Hybrid Heterojunctions for Enhanced Photocatalytic Hydrogen Production Activity. CHEMSUSCHEM 2020; 13:876-881. [PMID: 31944616 DOI: 10.1002/cssc.201903437] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/09/2020] [Indexed: 06/10/2023]
Abstract
Semiconductors and metals can form an Ohmic contact with an electric field pointing to the metal, or a Schottky contact with an electric field pointing to the semiconductor. If these two types of heterojunctions are constructed on a single nanoparticle, the two electric fields may cause a synergistic effect and increase the separation rate of the photogenerated electrons and holes. Metal Ni and Ag nanoparticles were successively loaded on the graphitic carbon nitride (g-C3 N4 ) surface by precipitation and photoreduction in the hope of forming hybrid heterojunctions on single nanoparticles. TEM/high-resolution TEM images showed that Ag and Ni were loaded on different locations on C3 N4 , which indicated that during the photoreduction reaction Ag+ obtained electrons from C3 N4 in the reduction reaction, whereas oxidation reactions proceeded on Ni nanoparticles. Photocatalytic hydrogen production experiments showed that C3 N4 -based hybrid heterojunctions can greatly improve the photocatalytic activity of materials. The possible reason is that two heterojunctions could form a long-range electric field similar to the p-i-n structure in semiconductors. Most of the photogenerated carriers were generated and then separated in this electric field, thereby increasing the separation rate of electrons and holes. This further improved the photocatalytic activity of C3 N4 .
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Direct Z-Scheme g-C 3N 4/FeWO 4 Nanocomposite for Enhanced and Selective Photocatalytic CO 2 Reduction under Visible Light. ACS APPLIED MATERIALS & INTERFACES 2019; 11:6174-6183. [PMID: 30681322 DOI: 10.1021/acsami.8b22434] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Photocatalytic reduction of CO2 to renewable solar fuels is considered to be a promising strategy to simultaneously solve both global warming and energy crises. However, development of a superior photocatalytic system with high product selectivity for CO2 reduction under solar light is the prime requisite. Herein, a series of nature-inspired Z-scheme g C3N4/FeWO4 composites are prepared for higher performance and selective CO2 reduction to CO as solar fuel under solar light. The novel direct Z-scheme coupling of the visible light-active FeWO4 nanoparticles with C3N4 nanosheets is seen to exhibit excellent performance for CO production with a rate of 6 μmol/g/h at an ambient temperature, almost 6 times higher compared to pristine C3N4 and 15 times higher than pristine FeWO4. More importantly, selectivity for CO is 100% over other carbon products from CO2 reduction and more than 90% over H2 products from water splitting. Our results clearly demonstrate that the staggered band structure between FeWO4 and C3N4 reflecting the nature-inspired Z-scheme system not only favors superior spatial separation of the electron-hole pair in g-C3N4/FeWO4 but also shows good reusability. The present work provides unprecedented insights for constructing the direct Z-scheme by mimicking the nature for high performance and selective photocatalytic CO2 reduction into solar fuels under solar light.
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Hierarchical Porous Nanosheets Constructed by Graphene-Coated, Interconnected TiO 2 Nanoparticles for Ultrafast Sodium Storage. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:1705788. [PMID: 29334133 DOI: 10.1002/adma.201705788] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 11/20/2017] [Indexed: 05/23/2023]
Abstract
Sodium-ion batteries (SIBs) are considered promising next-generation energy storage devices. However, a lack of appropriate high-performance anode materials has prevented further improvements. Here, a hierarchical porous hybrid nanosheet composed of interconnected uniform TiO2 nanoparticles and nitrogen-doped graphene layer networks (TiO2 @NFG HPHNSs) that are synthesized using dual-functional C3 N4 nanosheets as both the self-sacrificing template and hybrid carbon source is reported. These HPHNSs deliver high reversible capacities of 146 mA h g-1 at 5 C for 8000 cycles, 129 mA h g-1 at 10 C for 20 000 cycles, and 116 mA h g-1 at 20 C for 10 000 cycles, as well as an ultrahigh rate capability up to 60 C with a capacity of 101 mA h g-1 . These results demonstrate the longest cyclabilities and best rate capability ever reported for TiO2 -based anode materials for SIBs. The unprecedented sodium storage performance of the TiO2 @NFG HPHNSs is due to their unique composition and hierarchical porous 2D structure.
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[Performance and Mechanism Study of Visible Light-driven C 3N 4/BiOBr Composite Photocatalyst]. HUAN JING KE XUE= HUANJING KEXUE 2017; 38:2182-2190. [PMID: 29965127 DOI: 10.13227/j.hjkx.201606158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Efficient visible light-driven C3N4/BiOBr composite photocatalysts were prepared via a facile hydrothermal method and characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, UV-Vis diffuse reflectance spectra and photoluminescence spectra for the phase composition and optical property. Taking rhodamine B (RhB) as the target pollutant, the photocatalytic activity and stability of photocatalysts were studied under visible light irradiation. Furthermore, the mechanism in the process of photocatalytic degradation was discussed by electron spin resonance spectroscopy analysis and the trapping experiment of generated radicals. The results indicated that C3N4/BiOBr composite photocatalysts had excellent crystallization performance. Composited by C3N4, BiOBr exhibited considerably higher photocatalytic activity by reducing the rate of electron-hole recombination. Among prepared composites with various C3N4 contents, 15% C3N4/BiOBr exhibited the best efficiency for the degradation of RhB. After irradiation for 18 minutes, the degradation rate of RhB was 100%, which was 1.5 times higher than that using pure BiOBr. The results also suggested that holes and ·O2- were the main reactive species in the photocatalytic process for the RhB degradation, and holes played the leading role.
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Surface Modification of C 3N 4 through Oxygen-Plasma Treatment: A Simple Way toward Excellent Hydrophilicity. ACS APPLIED MATERIALS & INTERFACES 2016; 8:31419-31425. [PMID: 27767306 DOI: 10.1021/acsami.6b10516] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We developed a universal method to prepare hydrophilic carbon nitrogen (C3N4) nanosheets. By treating C3N4 nanosheets with oxygen plasma, hydroxylamine groups (N-OH) with intense protonation could be introduced on the surface; moreover, the content of N-OH groups increased linearly with the oxygen-plasma treatment time. Thanks to the excellent hydrophilicity, uniformly dispersed C3N4 solution were prepared, which was further translated into C3N4 paper by simple vacuum filtration. Pure C3N4 paper with good stability, excellent hydrophilicity, and biocompatibility were proved to have excellent performance in tissue repair. Further research demonstrated that the oxygen-plasma treatment method can also introduce N-OH groups into other nitrogen-containing carbon materials (NCMs) such as N-doped graphene, N-doped carbon nanotube, and C2N, which offers a new perspective on the surface modification and functionalization of these carbon nanomaterials.
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Defective, Porous TiO2 Nanosheets with Pt Decoration as an Efficient Photocatalyst for Ethylene Oxidation Synthesized by a C3N4 Templating Method. ACS APPLIED MATERIALS & INTERFACES 2016; 8:10104-10108. [PMID: 27070854 DOI: 10.1021/acsami.6b02725] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report herein a C3N4 templating method for successfully synthesizing defective, porous TiO2 nanosheets with Pt decoration as an efficient photocatalyst for C2H4 oxidation. During the synthetic procedure, C3N4 not only acts as a 2D template to direct synthesize porous TiO2 nanosheets (TiO2-NS) but also facilitates oxygen vacancy formation on TiO2. The resultant TiO2-NS shows enhanced UV and visible-light photoactivities toward C2H4 oxidation as compared to blank TiO2 (TiO2-B) prepared without C3N4 template. Subsquently, Pt nanoparticles are homogeneously decorated onto the surface of TiO2-NS. The as-obtained Pt-TiO2-NS exhibits efficient photocatalytic activity and stability toward ethylene oxidation.
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Graphitic C3 N4 -Sensitized TiO2 Nanotube Layers: A Visible-Light Activated Efficient Metal-Free Antimicrobial Platform. Chemistry 2016; 22:3947-51. [PMID: 26789421 DOI: 10.1002/chem.201505173] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Indexed: 11/09/2022]
Abstract
Herein, we use a facile procedure to graft a thin graphitic C3N4 (g-C3N4) layer on aligned TiO2 nanotube arrays (TiNT) by a one-step chemical vapor deposition (CVD) approach. This provides a platform to enhance the visible-light response of TiO2 nanotubes for antimicrobial applications. The formed g-C3N4/TiNT binary nanocomposite exhibits excellent bactericidal efficiency against Escherichia coli (E. coli) as a visible-light activated antibacterial coating, without the use of additional bactericides.
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Graphitic carbon nitride polymer as a recyclable photoredox catalyst for fluoroalkylation of arenes. Chemistry 2014; 21:526-30. [PMID: 25413695 DOI: 10.1002/chem.201405505] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Indexed: 11/10/2022]
Abstract
Heterogeneous catalysis for trifluoromethylations and perfluoroalkylations has been performed. Through the usage of cheap, metal-free and recyclable mesoporous graphitic carbon nitride (mpg-CN) it was possible to fluoroalkylate various arenes by the reductive activation of sulfonyl chlorides with visible light. Thus, we were able to demonstrate the robustness and versatility of mpg-CN as a photoredox catalyst beyond water splitting and the activation of oxygen.
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