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Black TiO2 films with unique porous structures have been successfully obtained in-situ on Ti plates by a simple hydrothermal treatment using H2O2 solution. The samples were used as photocatalysts to reduce CO2 under simulated sunl...
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Black TiO2 films with unique porous structures have been successfully obtained in-situ on Ti plates by a simple hydrothermal treatment using H2O2 solution. The samples were used as photocatalysts to reduce CO2 under simulated sunlight irradiation at room temperature in the presence of H2O. The films have excellent grid-like structures providing more active photocatalysis sites and exhibit extremely high CO2 photoreduction efficiency with favourable selective formation of CO and CH4 (with highest production rates of 115 and 12 mu mol/g h, respectively) compared to conventional TiO2 (Degussa P25) (0.28 and 0.019 mu mol/g h, respectively). The structural deviation from standard crystalline anatase with the existence of substantial Ti3+ and oxygen vacancies is the critical factor for expanding the absorbance of TiO2 into the visible light region and the resulting excellent photocatalytic performance under simulated sunlight irradiation. (C) 2015 Elsevier Ltd. All rights reserved.
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The Photoreduction of CO2provides a promising way to solving environmental issues. In this work, hydrogen-doped Titania powders were fabricated using NaBH4heated with TiO2at 350?°C. The reduced Titania was decorated with Platinum...
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The Photoreduction of CO2provides a promising way to solving environmental issues. In this work, hydrogen-doped Titania powders were fabricated using NaBH4heated with TiO2at 350?°C. The reduced Titania was decorated with Platinum nanoparticles by Poly (N-vinyl-2-pyrrolidone) PVP protected Pt solution. The copper precursor was mixed with the previous sample to get Cu-Pt bi-metal co-catalysts deposited on the surface of reduced TiO2. After wrapping with graphene oxide (GO) sheets, core-shell-structured photocatalysts graphene-wrapped Cu-Pt/rTiO2be synthesized. A systematic study of CO2photoreduction performance of graphene-wrapped Cu-Pt/rTiO2was conducted using the on-line GC system with SiO2fiber as the substrate. Under AM1.5 G simulated sunlight, the graphene-wrapped Cu-Pt/rTiO2@ SiO2produced carbon monoxide (394.84?μmol?g-1cat 1. h?1) from CO2with remarkable selectivity reaching 99%. Over 7?h of illumination period, the prepared sample was showing excellent stability with no decrease in origin CO2conversion rate. Elemental mapping and transmission electron microscopy images confirmed Cu-Pt bi-metal nanoparticles deposited on the surface of TiO2nanoparticles. The Inert gas control group test confirmed that carbon monoxide products originate from CO2.
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Photocatalytic CO2 reduction is a promising method to resolve the energy shortage problem. Developing photocatalysts with strong redox capabilities is urgently needed to achieve high photocatalytic activity. Herein, we synthesized...
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Photocatalytic CO2 reduction is a promising method to resolve the energy shortage problem. Developing photocatalysts with strong redox capabilities is urgently needed to achieve high photocatalytic activity. Herein, we synthesized TiO2/CsPbBr3 S-scheme heterojunctions with modulated internal electric field by facet engineering of TiO2 to control charge transfer for improved photocatalytic activity. Density func-tional theory (DFT) calculation reveals that there is a wider Fermi level difference between TiO2-(1 0 1) and CsPbBr3 than that between TiO2-(0 0 1) and CsPbBr3, which will induce more obvious band bending. Subsequently, more efficient spatial separation will occur around the interface. Thus, TiO2-(1 0 1)/CsPbBr3 heterostructures effectively reduce CO2 into CO with the selectivity of 90.2 % and reduction rate of 12.5 lmol h-1, 15.6 and 5.6 times improvement than that of 101-TiO2 and TiO2-(0 0 1)/CsPbBr3, respec-tively. This report proposes a feasible idea of employing facet engineering to take the advantage of S -scheme heterojunction. (c) 2022 Elsevier Inc. All rights reserved.
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Weak interaction between TiO2 and CO2 molecules is detrimental to CO2 photoreduction. To alleviate this drawback, ceria is usually exploited as a basic promoter, but fundamental insights into the correlation of ceria-tuned CO2 ads...
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Weak interaction between TiO2 and CO2 molecules is detrimental to CO2 photoreduction. To alleviate this drawback, ceria is usually exploited as a basic promoter, but fundamental insights into the correlation of ceria-tuned CO2 adsorption and the resulting activity of photoreduction are lacking. In this work, highly dispersed CeO2/TiO2 and bare TiO2 catalysts were fabricated and their structural, surface, and optical properties and activity for CO2 photoreduction were explored. Microcalorimetric measurement and in situ infrared spectroscopy were used to reveal the strengths and states of CO2 adsorption and the course of photoreduction of CO2 with H2O vapor. Monodentate carbonate (m-CO32-), bidentate carbonate (b-CO32-), and bidentate bicarbonate (b-HCO3-) are found to be the main surface species for the coadsorption of CO2 and H2O on catalyst surfaces. The presence of CeO2 containing Ce3+ strengthens the bonding of CO2 with catalyst surfaces and increases the production of b-CO32- and b-HCO3- species. Unlike m-CO32-, b-CO32- and b-HCO3- surface species could readily be transformed to surface CO2- in the presence of H2O under simulated sunlight irradiation. This might be attributed to the fact that the CO2 segment in the two species is bound to Ti/Ce atoms that have reductive capabilities under photoirradiation. In addition, the presence of CeO2 containing Ce3+ facilitates photogenerated charge separation. As a result, ceria-tuned CO2 adsorption and enhanced charge separation are jointly responsible for the increased activity of CeO2/TiO2 catalysts. (C) 2016 Elsevier Inc. All rights reserved.
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Photoreduction of CO2 to hydrocarbons is a sustainable energy technology which not only mitigates emissions but also provides alternative fuels. However, one of the largest challenges is to increase the overall CO2 photo-conversio...
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Photoreduction of CO2 to hydrocarbons is a sustainable energy technology which not only mitigates emissions but also provides alternative fuels. However, one of the largest challenges is to increase the overall CO2 photo-conversion efficiency when water is used as the reducing reagent. In this work, mesoporous silica supported Cu/TiO2 nanocomposites were synthesized through a one-pot sol-gel method, and the photoreduction experiments were carried out in a continuous-flow reactor using CO2 and water vapor as the reactants under the irradiation of a Xe lamp. The high surface area mesoporous silica substrate (>300 m2/g) greatly enhanced CO2 photoreduction, possibly due to improved TiO2 dispersion and increased adsorption of CO2 and H2O on the catalyst. CO was found to be the primary product of CO2 reduction for TiO2-Si02 catalysts without Cu. The addition of Cu species, which was identified to be Cu2O by the XPS, markedly increased the overall CO2 conversion efficiency as well as the selectivity to CH4, by suppressing the electron-hole recombination and enhancing multi-electron reactions. A synergistic effect was observed by combining the porous SiO2 support and the deposition of Cu on TiO2. The peak production rates of CO and CH4 reached 60 and 10μ-molg-cat~(-1) h~(-1), respectively, for the 0.5%Cu/TiO2-SiO2 composite that has the optimum Cu concentration; the peak quantum yield was calculated to be 1.41%. Deactivation and regeneration of the catalyst was observed and the mechanism was discussed. Desorption of the reaction intermediates from the active sites may be the rate limiting step.
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Photocatalytic conversion of CO2 into hydrocarbons by utilization of the solar energy is considered a promising approach to mitigate energy crisis and the environmental issues. Since the defects in a catalyst play an important rol...
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Photocatalytic conversion of CO2 into hydrocarbons by utilization of the solar energy is considered a promising approach to mitigate energy crisis and the environmental issues. Since the defects in a catalyst play an important role in CO2 reduction, herein, the porous ZnO nanoplates with vacancy defects are synthesized by annealing ZnS (en)(0.5) precursor in air at different temperature. The defect amount in ZnO changes with the annealing temperature, resulting in different photocatalytic activity for CO2 reduction. The related mechanism has been studied both experimentally and theoretically. Raman spectra and chemical composition of the obtained catalysts are used to determine the defects. Transient techniques are used to investigate the separation of photogenerated charge carriers. CO2 adsorption capacity for different catalysts is also measured. First-principles calculation is used to study the adsorption and activation of CO2 on the ZnO surface. We envision that this work may afford an efficient approach to develop the semiconductor photocatalysts with superior activity via defects engineering.
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A highly efficient electrostatic inducted CO2 photoreduction system is introduced. When 45 kV of electrostatic force was applied, 6.26% of quantum yield of CO2 photoreduction reaction was achieved (equivalent to 184.44 umol/g h) u...
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A highly efficient electrostatic inducted CO2 photoreduction system is introduced. When 45 kV of electrostatic force was applied, 6.26% of quantum yield of CO2 photoreduction reaction was achieved (equivalent to 184.44 umol/g h) using pure TiO2 nanorods that grown on FTO glass as the photocatalyst. (c) 2015 Elsevier B.V. All rights reserved.
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Copper or cobalt incorporated TiO2 supported ZSM-5 catalysts were prepared by a sol-gel method, and then were characterized by XRD, BET, XPS and UV-vis diffuse reflectance spectroscopy. Ti3+ was the main titanium specie in TiO2/ZS...
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Copper or cobalt incorporated TiO2 supported ZSM-5 catalysts were prepared by a sol-gel method, and then were characterized by XRD, BET, XPS and UV-vis diffuse reflectance spectroscopy. Ti3+ was the main titanium specie in TiO2/ZSM-5 and Cu-TiO2/ZSM-5, which will be oxide to Ti4+ after Co was doped. With the deposition of Cu or Co, the efficiency of the CO2 conversion to CH3OH was increased under low energy irradiation. The peak production rate of CH3OH reached 50.05 and 35.12 mu mol g(-1) h(-1), respectively. High photo energy efficiency (PEE) and quantum yield (phi) were also reached. The mechanism was discussed in our study. (C) 2014 Elsevier B.V. All rights reserved.
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The visible-light responsive photocatalyst BiVO4 was synthesized, and its photocatalytic reduction of CO2 in water was examined. Our study shows the selective formation of ethanol under the condition of high intensity visible-ligh...
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The visible-light responsive photocatalyst BiVO4 was synthesized, and its photocatalytic reduction of CO2 in water was examined. Our study shows the selective formation of ethanol under the condition of high intensity visible-light irradiation, and suggests that intense irradiation generates a large number of G1 intermediate species anchored on the surface of BiVO4, which dimerize to form ethanol. For the photocatalytic reduction of CO2 into ethanol, monoclinic BiVO4 is more efficient than tetragonal BiVO4.
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A series of TiO2/nitrogen (N) doped reduced graphene oxide (TiO2/NrGO) nanocomposites with varying concentration and bonding configurations of nitrogen were synthesized by a one-step urea-assisted hydrothermal method, and applied ...
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A series of TiO2/nitrogen (N) doped reduced graphene oxide (TiO2/NrGO) nanocomposites with varying concentration and bonding configurations of nitrogen were synthesized by a one-step urea-assisted hydrothermal method, and applied to photoreduction of CO2 with H2O vapor in the gas-phase under the irradiation of a Xe lamp. The effect of the N dopant (doping quantity and bonding configuration) on the catalytic performance of TiO2/NrGO was examined. In particular, TiO2/NrGO-300, with a 300:1 mass ratio of urea/GO in precursor solution, had the highest CO production yield (356.5 mu mol g(-1)), manifesting a significant 4.4 and 2.2-fold enhancements of CO yield over pure TiO2 and TiO2/rGO, respectively. More significantly, TiO2/NrGO showed excellent catalytic stability during the prolonged reaction, while catalytic deactivation was observed for both pristine TiO2 and TiO2/rGO after a few hours. The promoting effects of N dopants on the structure and activity of TiO2/NrGO were investigated. It was demonstrated that NrGO with an appropriate N quantity and N -bonding configuration acted as a dual-functional promoter, simultaneously enhancing CO2 adsorption on the catalyst surface and facilitating electron-hole separation, while eventually boosted the photocatalytic performance. Experimental results in this work provide a better understanding of the critical roles of N dopants in the synthesized composites and also inspire the ongoing interest in better design of other N-doped graphene based materials for photoreduction of CO2. (C) 2017 Elsevier B.V. All rights reserved.
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