Ultra-Thin Carbon-Doped Bi2WO6 Nanosheets for Enhanced Photocatalytic CO2 Reduction

AbstractThe photocatalytic reduction of CO2 is a promising strategy to generate chemical fuels. However, this reaction usually suffers from low photoactivity because of insufficient light absorption and rapid charge recombination. Defect engineering has become an effective approach to improve the photocatalytic activity. Herein, ultra-thin (~ 4.1 nm) carbon-doped Bi2WO6 nanosheets were prepared via hydrothermal treatment followed by calcination. The ultra-thin nanosheet structure of the catalyst not only provides more active sites but also shortens the diffusion distance of charge carriers, thereby suppressing charge recombination. Moreover, carbon doping could successfully extend the light absorption range of the catalyst and remarkably promote charge separation, thus inhibiting recombination. As a result, the as-prepared Bi2WO6 photocatalyst with ultra-thin nanosheet structure and carbon doping exhibits enhanced photocatalytic CO2 reduction performance, which is twice that of pristine ultra-thin Bi2WO6 nanosheet. This study highlights the importance of defect engineering in photocatalytic energy conversion and provides new insights for fabricating efficient photocatalysts.

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Engineering the Surface Structure of MoS2 Nanosheets by Carbon-Doping with Rich Defects to Tune UV-Visible Light Absorption Property

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.735.185 ◽

2017 ◽

Vol 735 ◽

pp. 185-188 ◽

Cited By ~ 3

Author(s):

Zhen Yin Hai ◽

Jian Gong Du ◽

Chen Yang Xue ◽

Dan Feng Cui ◽

Mohammad Karbalaei Akbari ◽

...

Keyword(s):

Visible Light ◽

Light Absorption ◽

Photo Luminescence ◽

Optical Bandgap ◽

Carbon Doping ◽

Absorption Property ◽

Visible Light Absorption ◽

Carbon Doped ◽

Uv Visible ◽

Light Absorption Property

A facile doping method utilizing inexpensive raw materials was proposed to achieve variation in optical bandgap and UV-visible light absorption property of MoS2 nanosheets. Carbon-assistant heating with degreasing cotton has demonstrated the development of carbon-doped MoS2 nanosheets with enhanced rich defects. The results obtained shown that modified MoS2 nanosheets with the lateral width of ~600 nm are exhibited shift of the intensively blue peaks of photo-luminescence (PL) comparing to those MoS2 nanosheets with a lateral dimension of larger than 1 μm. Optical bandgap of the carbon-doped MoS2 nanosheets was found to be broader than that of the pure MoS2 nanosheets and the prepared samples also exhibited a broadband UV-visible light absorption property.

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Vacancy-Defect Modulated Pathway of Photoreduction of CO2 on Quaternary Single Atomically Thin AgInP2S6 Sheets toward Boosting Efficient and Selective Production of Value-Added Olefiant Gas

10.21203/rs.3.rs-225023/v1 ◽

2021 ◽

Author(s):

Yong Zhou ◽

Zhigang Zou ◽

Wa Gao ◽

Xiaoyong Wang ◽

Qing Shen ◽

...

Keyword(s):

Reaction Pathway ◽

Co2 Reduction ◽

Value Added ◽

Catalytic Efficiency ◽

Atomic Layer ◽

Major Product ◽

Vacancy Defect ◽

Charge Carriers ◽

Defect Engineering

Abstract The quaternary AgInP2S6 atomic layer with the thickness of ~ 0.70 nm were successfully synthesized through facile ultrasonic exfoliation of the corresponding bulk crystal. The ultrathin sheet exhibits efficiently photocatalytic conversion of CO2 into CO as a major product and minority of CH4 and C2H4 in the presence of water vapor. The sulfur defect engineering on this atomic layer through a H2O2 etch process can excitingly enable to change the CO2 photoreduction reaction pathway to steer dominant generation of ethene (C2H4) important chemical with the yield-based selectivity reaching ~73% and the electron-based selectivity as high as ~89%, and the quantum yield of 0.51% at wavelength of 415 nm. Both DFT calculation and in-situ FTIR demonstrate as the introduction of S vacancies in AgInP2S6 causes the charge accumulation on the Ag atoms near the S vacancies, the exposed Ag sites can thus effectively capture the forming *CO molecules, making the catalyst surface enrich with key reaction intermediates to lower the C-C binding coupling barrier, which facilitates the production of C2H4. Surface photovoltage measurement confirms that atomically ultrathin structure of the exfoliated AgInP2S6 can shorten the transfer distance of charge carriers from the interior onto the surface, thus decrease the recombination in body and improve the catalytic efficiency. This work may provide fresh insights into the design of atomically thin photocatalyst framework for CO2 reduction and establish an ideal platform for reaffirming the versatility of defect engineering in tuning catalytic activity and selectivity.

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Improving Photocatalytic Degradation Activity of Organic Pollutant by Sn4+ Doping of Anatase TiO2 Hierarchical Nanospheres with Dominant {001} Facets

Nanomaterials ◽

10.3390/nano9111603 ◽

2019 ◽

Vol 9 (11) ◽

pp. 1603 ◽

Cited By ~ 4

Author(s):

Meiling Sun ◽

Weichong Kong ◽

Yunlong Zhao ◽

Xiaolin Liu ◽

Jingyue Xuan ◽

...

Keyword(s):

Light Absorption ◽

Active Sites ◽

Organic Pollutant ◽

Photogenerated Electron ◽

High Energy ◽

Charge Carriers ◽

Photon Absorption ◽

Hydroxyl Group ◽

Molar Ratio ◽

Electron Hole

Herein, high-energy {001} facets and Sn4+ doping have been demonstrated to be effective strategies to improve the surface characteristics, photon absorption, and charge transport of TiO2 hierarchical nanospheres, thereby improving their photocatalytic performance. The TiO2 hierarchical nanospheres under different reaction times were prepared by solvothermal method. The TiO2 hierarchical nanospheres (24 h) expose the largest area of {001} facets, which is conducive to increase the density of surface active sites to degrade the adsorbed methylene blue (MB), enhance light scattering ability to absorb more incident photons, and finally, improve photocatalytic activity. Furthermore, the SnxTi1−xO2 (STO) hierarchical nanospheres are fabricated by Sn4+ doping, in which the Sn4+ doping energy level and surface hydroxyl group are beneficial to broaden the light absorption range, promote the generation of charge carriers, and retard the recombination of electron–hole pairs, thereby increasing the probability of charge carriers participating in photocatalytic reactions. Compared with TiO2 hierarchical nanospheres (24 h), the STO hierarchical nanospheres with 5% nSn/nTi molar ratio exhibit a 1.84-fold improvement in photodegradation of MB arising from the enhanced light absorption ability, increased number of photogenerated electron–hole pairs, and prolonged charge carrier lifetime. In addition, the detailed mechanisms are also discussed in the present paper.

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The origin of enhanced photocatalytic activities of hydrogenated TiO2 nanoparticles

Dalton Transactions ◽

10.1039/c7dt00827a ◽

2017 ◽

Vol 46 (32) ◽

pp. 10694-10699 ◽

Cited By ~ 14

Author(s):

Yani Liu ◽

Haifeng Feng ◽

Xiaobing Yan ◽

Jiaou Wang ◽

Huagui Yang ◽

...

Keyword(s):

Electronic Structure ◽

Photocatalytic Activity ◽

Tio2 Nanoparticles ◽

Light Absorption ◽

Active Sites ◽

Size Structure ◽

Charge Carriers ◽

Photocatalytic Activities ◽

Catalytically Active ◽

Photoinduced Charge

The photocatalytic activity of semiconductors is largely governed by their light absorption, separation of photoinduced charge carriers and surface catalytically active sites, which are primarily controlled by the morphology, crystalline size, structure, and especially the electronic structure of photocatalysts.

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Role of the Structure and Electronic Properties of Fe2O3-MoO3 Catalyst on the Dehydration of Isopropyl Alcohol

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19931591 ◽

1993 ◽

Vol 58 (7) ◽

pp. 1591-1599 ◽

Cited By ~ 3

Author(s):

Abd El-Aziz A. Said

Keyword(s):

Active Sites ◽

Isopropyl Alcohol ◽

Oxide Catalyst ◽

Flow System ◽

Charge Carriers ◽

X Ray Diffraction ◽

X Ray ◽

Catalyst Composition ◽

Surface Active

Molybdenum oxide catalyst doped or mixed with (1 - 50) mole % Fe3+ ions were prepared. The structure of the original samples and the samples calcined at 400 °C were characterized using DTA, X-ray diffraction and IR spectra. Measurements of the electrical conductivity of calcined samples with and without isopropyl alcohol revealed that the conductance increases on increasing the content of Fe3+ ions up to 50 mole %. The activation energies of charge carriers were determined in presence and absence of the alcohol. The catalytic dehydration of isopropyl alcohol was carried out at 250 °C using a flow system. The results obtained showed that the doped or mixed catalysts are active and selective towards propene formation. However, the catalyst containing 40 mole % Fe3+ ions exhibited the highest activity and selectivity. Correlations were attempted to the catalyst composition with their electronic and catalytic properties. Probable mechanism for the dehydration process is proposed in terms of surface active sites.

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Defect engineering and characterization of active sites for efficient electrocatalysis

Nanoscale ◽

10.1039/d0nr08976a ◽

2021 ◽

Vol 13 (6) ◽

pp. 3327-3345

Author(s):

Xuecheng Yan ◽

Linzhou Zhuang ◽

Zhonghua Zhu ◽

Xiangdong Yao

Keyword(s):

Transition Metal ◽

Active Sites ◽

Defect Engineering ◽

Metal Free

This review highlights recent advancements in defect engineering and characterization of both metal-free carbons and transition metal-based electrocatalysts.

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Investigation of Gas Diffusion Electrode Systems for the Electrochemical CO2 Conversion

Catalysts ◽

10.3390/catal11040482 ◽

2021 ◽

Vol 11 (4) ◽

pp. 482

Author(s):

Hilmar Guzmán ◽

Federica Zammillo ◽

Daniela Roldán ◽

Camilla Galletti ◽

Nunzio Russo ◽

...

Keyword(s):

Carbon Capture ◽

Active Sites ◽

Co2 Reduction ◽

Gas Diffusion ◽

Gas Diffusion Electrode ◽

Catalyst Loading ◽

Co2 Conversion ◽

Atmospheric Conditions ◽

Electrochemical Co2 Reduction ◽

Liquid Products

Electrochemical CO2 reduction is a promising carbon capture and utilisation technology. Herein, a continuous flow gas diffusion electrode (GDE)-cell configuration has been studied to convert CO2 via electrochemical reduction under atmospheric conditions. To this purpose, Cu-based electrocatalysts immobilised on a porous and conductive GDE have been tested. Many system variables have been evaluated to find the most promising conditions able to lead to increased production of CO2 reduction liquid products, specifically: applied potentials, catalyst loading, Nafion content, KHCO3 electrolyte concentration, and the presence of metal oxides, like ZnO or/and Al2O3. In particular, the CO productivity increased at the lowest Nafion content of 15%, leading to syngas with an H2/CO ratio of ~1. Meanwhile, at the highest Nafion content (45%), C2+ products formation has been increased, and the CO selectivity has been decreased by 80%. The reported results revealed that the liquid crossover through the GDE highly impacts CO2 diffusion to the catalyst active sites, thus reducing the CO2 conversion efficiency. Through mathematical modelling, it has been confirmed that the increase of the local pH, coupled to the electrode-wetting, promotes the formation of bicarbonate species that deactivate the catalysts surface, hindering the mechanisms for the C2+ liquid products generation. These results want to shine the spotlight on kinetics and transport limitations, shifting the focus from catalytic activity of materials to other involved factors.

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Defect engineering of photocatalysts towards elevated CO2 reduction performance

ChemSusChem ◽

10.1002/cssc.202100677 ◽

2021 ◽

Author(s):

Meng Shen ◽

Lingxia Zhang ◽

Jianlin Shi

Keyword(s):

Elevated Co2 ◽

Co2 Reduction ◽

Defect Engineering

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Improving the Catalytic CO2 Reduction on Cs2AgBiBr6 by Halide Defect Engineering: A DFT Study

Materials ◽

10.3390/ma14102469 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2469

Author(s):

Pengfei Chen ◽

Yiao Huang ◽

Zuhao Shi ◽

Xingzhu Chen ◽

Neng Li

Keyword(s):

Gas Adsorption ◽

Catalytic Reduction ◽

Deep Level ◽

Critical Role ◽

Co2 Reduction ◽

First Principles Calculation ◽

Bandgap Energy ◽

Practical Implementation ◽

Co2 Conversion ◽

Defect Engineering

Pb-free double halide perovskites have drawn immense attention in the potential photocatalytic application, due to the regulatable bandgap energy and nontoxicity. Herein, we first present a study for CO2 conversion on Pb-free halide perovskite Cs2AgBiBr6 under state-of-the-art first-principles calculation with dispersion correction. Compared with the previous CsPbBr3, the cell parameter of Cs2AgBiBr6 underwent only a small decrease of 3.69%. By investigating the adsorption of CO, CO2, NO, NO2, and catalytic reduction of CO2, we found Cs2AgBiBr6 exhibits modest adsorption ability and unsatisfied potential determining step energy of 2.68 eV in catalysis. We adopted defect engineering (Cl doping, I doping and Br-vacancy) to regulate the adsorption and CO2 reduction behavior. It is found that CO2 molecule can be chemically and preferably adsorbed on Br-vacancy doped Cs2AgBiBr6 with a negative adsorption energy of −1.16 eV. Studying the CO2 reduction paths on pure and defect modified Cs2AgBiBr6, Br-vacancy is proved to play a critical role in decreasing the potential determining step energy to 1.25 eV. Finally, we probe into the electronic properties and demonstrate Br-vacancy will not obviously promote the process of catalysis deactivation, as there is no formation of deep-level electronic states acting as carrier recombination center. Our findings reveal the process of gas adsorption and CO2 reduction on novel Pb-free Cs2AgBiBr6, and propose a potential strategy to improve the efficiency of catalytic CO2 conversion towards practical implementation.

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