The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is high...The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is highly intriguing and challenging to promote the selectivity and efficiency of visible-light-responsive photocatalysts that favor the adsorption of CO2 in photoreduction processes.In this work,three-dimensional hierarchical Cd0.8Zn0.2S flowers(C8Z2S-F)with ultrathin petals were successfully synthesized through an in-situ self-assembly growth process using sodium citrate as a morphology director.The flower-like Cd0.8Zn0.2S solid solution exhibited remarkable photocatalytic performance in the reduction of CO2,generating CO up to 41.4μmol g^−1 under visible-light illumination for 3 h;this was nearly three times greater than that of Cd0.8Zn0.2S nanoparticles(C8Z2S-NP)(14.7μmol g^−1).Particularly,a comparably high selectivity of 89.9%for the conversion of CO2 to CO,with a turnover number of 39.6,was obtained from the solar-driven C8Z2S-F system in the absence of any co-catalyst or sacrificial agent.Terahertz time-domain spectroscopy indicated that the introduction of flower structures enhanced the light-harvesting capacity of C8Z2S-F.The in situ diffuse reflectance infrared Fourier transform spectroscopy unveiled the existence of surface-adsorbed species and the conversion of photoreduction intermediates during the photocatalytic process.Empirical characterizations and predictions of the photocatalytic mechanism demonstrated that the flower-like Cd0.8Zn0.2S solid solution possessed desirable CO2 adsorption properties and an enhanced charge-transfer capability,thus providing a highly effective photocatalytic reduction of CO2.展开更多
Photocatalytic reduction of CO2 into various types of fuels has attracted great interest,and serves as a potential solution to addressing current global warming and energy challenges.In this work,Ag-Cu nanoparticles a...Photocatalytic reduction of CO2 into various types of fuels has attracted great interest,and serves as a potential solution to addressing current global warming and energy challenges.In this work,Ag-Cu nanoparticles are densely supported on N-doped TiO2 nanowire through a straightforward nanofabrication approach.The range of light absorption by N-doped TiO2 can be tuned to match the plasmonic band of Ag nanoparticles,which allows synergizing a resonant energy transfer process with the Schottky junction.Meanwhile,Cu nanoparticles can provide active sites for the reduction of CO2 molecules.Remarkably,the performance of photocatalytic CO2 reduction is improved to produce CH4 at a rate of 720μmol·g-1·h-1 under full-spectrum irradiation.展开更多
Photocatalytic CO2 reduction holds promise as a future technology for the manufacture of fuels and commodity chemicals.However,factors controlling product selectivity remain poorly understood.Herein,we compared the pe...Photocatalytic CO2 reduction holds promise as a future technology for the manufacture of fuels and commodity chemicals.However,factors controlling product selectivity remain poorly understood.Herein,we compared the performance of a homologous series of Zn-based layered double hydroxide(ZnM-LDH)photocatalysts for CO2 reduction.By varying the trivalent or tetravalent metal cations in the ZnM-LDH photocatalysts(M=Ti4+,Fe3+,Co3+,Ga3+,Al3+),the product selectivity of the reaction could be precisely controlled.ZnTi-LDH afforded CH4 as the main reduction product;ZnFe-LDH and ZnCo-LDH yielded H2 exclusively from water splitting;whilst ZnGa-LDH and ZnAl-LDH generated CO.In-situ diffuse reflectance infrared measurements,valence band XPS and density function theory calculations were applied to rationalize the CO2 reduction selectivities of the different ZnM-LDH photocatalysts.The analyses revealed that the d-band center(ed)position of the M3+or M4+cations controlled the adsorption strength of CO2 and thus the selectivity to carbon-containing products or H2.Cations with d-band centers relatively close to the Fermi level(Ti4+,Ga3+and Al3+)adsorbed CO2 strongly yielding CH4 or CO,whereas metal cations with d-band centers further from the Fermi level(Fe3+and Co3+)adsorbed CO2 poorly,thereby yielding H2 only(from water splitting).Our findings clarify the role of trivalent and tetravalent metal cations in LDH photocatalysts for the selective CO2 reduction,paving new ways for the development of improved LDH photocatalyst with high selectivities to specific products.展开更多
Photocatalytic CO2 reduction on metal-oxide-based catalysts is promising for solving the energy and environmental crises faced by mankind. The oxygen vacancy （Vo） on metal oxides is expected to be a key factor affec...Photocatalytic CO2 reduction on metal-oxide-based catalysts is promising for solving the energy and environmental crises faced by mankind. The oxygen vacancy （Vo） on metal oxides is expected to be a key factor affecting the efficiency of photocatalytic CO2 reduction on metal-oxide-based catalysts. Yet, to date, the question of how an Vo influences photocatalytic CO2 reduction is still unanswered. Herein, we report that, on Vo-rich gallium oxide coated with Pt nanoparticles （Vo-rich Pt/Ga203）, CO2 is photocatalytically reduced to CO, with a highly enhanced CO evolution rate （21.0umol.h-1） compared to those on Vo-poor Pt/Ga2O3 （3.9 gmol-h-1） and Pt/TiO2（P25） （6.7 gmol.h-1）. We demonstrate that the Vo leads to improved CO2 adsorption and separation of the photoinduced charges on Pt/Ga203, thus enhancing the photocatalytic activity of Pt/Ga203. Rational fabrication of an Vo is thereby an attractive strategy for developing efficient catalysts for photocatalytic CO2 reduction.展开更多
Metal nanoparticle （NP） co-catalysts on metal oxide semiconductor supports are attracting attention as photocatalysts for a variety of chemical reactions. Related efforts seek to make and use Pt-free catalysts. In t...Metal nanoparticle （NP） co-catalysts on metal oxide semiconductor supports are attracting attention as photocatalysts for a variety of chemical reactions. Related efforts seek to make and use Pt-free catalysts. In this regard, we report here enhanced CH4 formation rates of 25 and 60 μmol·g^-1·h^-1 by photocatalytic CO2 reduction using hitherto unused ZnPd NPs as well as Au and Ru NPs. The NPs are formed by colloidal synthesis and grafted onto short n-type anatase TiO2 nanotube arrays （TNAs）, grown anodically on transparent glass substrates. The interfacial electric fields in the NP-grafted TiO2 nanotubes were probed by ultraviolet photoelectron spectroscopy （UPS）. Au NP-grafted TiO2 nanotubes （Au-TNAs） showed no band bending, but a depletion region was detected in Ru NP-grafted TNAs （Ru-TNAs） and an accumulation layer was observed in ZnPd NP-grafted TNAs （ZnPd-TNAs）. Temperature programmed desorption （TPD） experiments showed significantly greater CO2 adsorption on NP-grafted TNAs. TNAs with grafted NPs exhibit broader and more intense UV-visible absorption bands than bare TNAs. We found that CO2 photoreduction by nanoparticle-grafted TNAs was driven not only by ultraviolet photons with energies greater than the TiO2 band gap, but also by blue photons close to and below the anatase band edge. The enhanced rate of CO2 reduction is attributed to superior use of blue photons in the solar spectrum, excellent reactant adsorption, efficient charge transfer to adsorbates, and low recombination losses.展开更多
Nitrogen-doped anatase TiO 2 microsheets with 65%（001） and 35%（101） exposed faces were fabricated by the hydrothermal method using TiN as precursor in the presence of HF and HCl. The samples were characterized by ...Nitrogen-doped anatase TiO 2 microsheets with 65%（001） and 35%（101） exposed faces were fabricated by the hydrothermal method using TiN as precursor in the presence of HF and HCl. The samples were characterized by scanning electron microscopy,X-ray diffraction,N2 adsorption,X-ray photoelectron spectroscopy,UV-visible spectroscopy,and electrochemical impedance spectroscopy. Their photocatalytic activity was evaluated using the photocatalytic reduction of CO2. The N-doped TiO 2 sample exhibited a much higher visible light photocatalytic activity for CO2 reduction than its precursor TiN and commercial TiO 2（P25）. This was due to the synergistic effect of the formation of surface heterojunctions on the TiO 2 microsheet surface,enhanced visible light absorption by nitrogen-doping,and surface fluorination.展开更多
Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow micro...Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow microspheres(HS),were dedicatedly designed to boost overall photocatalytic efficiency.TiO_(2) nanoparticles were in-situ decorated on the inside and outside the shell of Cd S HS,ensuring close contact between TiO_(2) and CdS.The CdS/TiO2 HS with abundant mesopores inside of the shell boost the light absorption via multiscattering effect as well as accessible to reactions in all directions.The heterojunction was scrutinized and the charge transfer across it was revealed by in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS).Ultimately,the charge transfer in this composite was determined to follow stepscheme mechanism,which not only facilitates the separation of charge carriers but also preserves strong redox ability.Benefited from the intimate linkage between Cd S and TiO_(2) and the favorable step-scheme heterojunction,enhanced photocatalytic CO_(2) reduction activity was accomplished.The CH4 yield rate of CdS/TiO_(2) reaches 27.85μmol g^(–1) h^(–1),which is 145.6 and 3.8 times higher than those of pristine CdS and TiO_(2),respectively.This work presents a novel insight into constructing step-scheme photocatalytic system with desirable performance.展开更多
The active site amount of photocatalysts,being the key factors in photocatalytic reactions,directly affects the photocatalytic performance of the photocatalyst.Pristine graphitic carbon nitride(g‐C_(3)N_(4))exhibits ...The active site amount of photocatalysts,being the key factors in photocatalytic reactions,directly affects the photocatalytic performance of the photocatalyst.Pristine graphitic carbon nitride(g‐C_(3)N_(4))exhibits moderate photocatalytic activity due to insufficient active sites.In this study,cyano‐modified porous g‐C_(3)N_(4)nanosheets(MCN‐0.5)were synthesized through molecular self‐assembly and alkali‐assisted strategies.The cyano group acted as the active site of the photocatalytic reaction,because the good electron‐withdrawing property of the cyano group promoted carrier separation.Benefiting from the effect of the active sites,MCN‐0.5 exhibited significantly enhanced photocatalytic activity for CO2 reduction under visible light irradiation.Notably,the photocatalytic activity of MCN‐0.5 was significantly reduced when the cyano groups were removed by hydrochloric acid(HCl)treatment,further verifying the role of cyano groups as active sites.The photoreduction of Pt nanoparticles provided an intuitive indication that the introduction of cyano groups provided more active sites for the photocatalytic reaction.Furthermore,the controlled experiments showed that g‐C_(3)N_(4)grafted with cyano groups using melamine as the precursor exhibited enhanced photocatalytic activity,which proved the versatility of the strategy for enhancing the activity of g‐C_(3)N_(4)via cyano group modification.In situ diffuse reflectance infrared Fourier transform spectroscopy and theoretical calculations were used to investigate the mechanism of enhanced photocatalytic activity for CO2 reduction by cyano‐modified g‐C_(3)N_(4).This work provides a promising route for promoting efficient solar energy conversion by designing active sites in photocatalysts.展开更多
Crystalline TiO（P25） and isolated titanate species in a ZSM-5 structure（TS-1） were modified with Au and Ag, respectively, and tested in the gas-phase photocatalytic COreduction under high purity conditions. The no...Crystalline TiO（P25） and isolated titanate species in a ZSM-5 structure（TS-1） were modified with Au and Ag, respectively, and tested in the gas-phase photocatalytic COreduction under high purity conditions. The noble metal modification was performed by photodeposition. Light absorbance properties of the catalysts are examined with UV–Vis spectroscopy before and after the activity test. In the gas-phase photocatalytic COreduction, it was observed that the catalysts with Ag nanostructures are more active than those with Au nanostructures. It is thus found that the energetic difference between the band gap energy of the semiconductor and the position of the plasmon is influencing the photocatalytic activity.Potentially, plasmon excitation due to visible light absorption results in plasmon resonance energy, which affects the excitation of the semiconductor positively. Therefore, an overlap between band gap energy of the semiconductor and metal plasmon is needed.展开更多
Hierarchical heterostructure photocatalysts with broad spectrum solar light utilization,particularly in the nearinfrared(NIR)region,are emerging classes of advanced photocatalytic materials for solar-driven CO2 conver...Hierarchical heterostructure photocatalysts with broad spectrum solar light utilization,particularly in the nearinfrared(NIR)region,are emerging classes of advanced photocatalytic materials for solar-driven CO2 conversion into value-added chemical feedstocks.Herein,a novel two-demensional/three-demensional(2 D/3 D)hierarchical composite is hydrothermally synthesized by assembling vertically-aligned ZnIn2 S4(ZIS)nanowall arrays on nitrogen-doped graphene foams(NGF).The prepared ZIS/NGF composite shows enhancement in photothermal conversion ability and selective CO2 capture as well as solar-driven CO2 photoreduction.At273 K and 1 atm,the ZIS/NGF composite with 1.0 wt%NGF achieves a comparably high CO2-to-N2 selectivity of 30.1,with an isosteric heat of CO2 adsorption of 48.2 kJ mol^-1.And in the absence of cocatalysts and sacrificial agents,the ZIS/NGF composite with cyclability converts CO2 into CH4,CO and CH3 OH under simulated solar light illumination,with the respective evolution rates about 9.1,3.5,and 5.9 times higher than that of the pristine ZIS.In-depth analysis using in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS)in conjunction with Kelvin probe measurements reveals the underlying charge transfer pathway and process from ZIS to NGF.展开更多
Although both the aerobic photocatalytic oxidation of organic pollutants into CO2 and the anaerobic photocatalytic reduction of CO2 into solar fuels have been intensively studied,few efforts have been devoted to combi...Although both the aerobic photocatalytic oxidation of organic pollutants into CO2 and the anaerobic photocatalytic reduction of CO2 into solar fuels have been intensively studied,few efforts have been devoted to combining these carbon-involved photocatalytic oxidation-reduction processes together,by which an artificial photocatalytic carbon cycling process can be established.The key challenge lies in the exploitation of efficient bifunctional photocatalysts,capable of triggering both aerobic oxidation and anaerobic reduction reactions.In this work,a bifunctional ternary g-C3N4/Bi/BiVO4 hybrid photocatalyst is successfully constructed,which not only demonstrates superior aerobic photocatalytic oxidation performance in degrading an organic pollutant(using the dye,Rhodamine B as a model),but also exhibits impressive photocatalytic CO2 reduction performance under anaerobic conditions.Moreover,a direct conversion of Rhodamine B to solar fuels in a one-pot anaerobic reactor can be achieved with the as-prepared ternary g-C3N4/Bi/BiVO4 hybrid photocatalyst.The excellent bifunctional photocatalytic performance of the g-C3N4/Bi/BiVO4 photocatalyst is associated with the formation of efficient S-scheme hybrid junctions,which contribute to promoting the appropriate charge dynamics,and sustaining favorable charge potentials.The formation of the S-scheme heterojunction is supported by scavenger studies and density functional theory calculations.Moreover,the in-situ formed plasmonic metallic Bi nanoparticles in the S-scheme hybrid g-C3N4/Bi/BiVO4 photocatalyst enhances vectorial interfacial electron transfer.This novel bifunctional S-scheme g-C3N4/Bi/BiVO4 hybrid photocatalyst system provides new insights for the further development of an integrated aerobic-anaerobic reaction system for photocatalytic carbon cycling.展开更多
Hierarchically nanostructured, porous TiO_2(B) microspheres were synthesized by a microwave-assisted solvothermal method combined with subsequent heat treatment in air. The materials were carefully characterized by sc...Hierarchically nanostructured, porous TiO_2(B) microspheres were synthesized by a microwave-assisted solvothermal method combined with subsequent heat treatment in air. The materials were carefully characterized by scanning and transmission electron microscopy, X-ray diffraction, CO_2 adsorption, and a range of spectroscopies, including Raman, infrared, X-ray photoelectron and UV-Vis spectroscopy. The hierarchical TiO_2(B) particles are constructed by ultrathin nanosheets and possess large specific surface area, which provided many active sites for CO_2 adsorption as well as CO_2 conversion. The TiO_2(B)nanostructures exhibited marked photocatalytic activity for CO_2 reduction to methane and methanol. Anatase TiO_2 and P25 were used as the reference photocatalysts. Transient photocurrent measurement also proved the higher photoactivity of TiO_2(B) than that of anatase TiO_2. In-situ infrared spectrum was measured to identify the intermediates and deduce the conversion process of CO_2 under illumination over TiO_2(B) photocatalyst.展开更多
A rare-earth free upconversion luminescent material, 10BaF2：NaF, Na3AIF6, is synthesized by a hydrothermal method. The study of fluorescent spectrum indicates that it can convert visible light （550 nm-610 nm） into ...A rare-earth free upconversion luminescent material, 10BaF2：NaF, Na3AIF6, is synthesized by a hydrothermal method. The study of fluorescent spectrum indicates that it can convert visible light （550 nm-610 nm） into ultraviolet light （290 nm 350 nm）, and two emission peaks at 304 nm and 324 nm are observed under the excitation of 583 nm at room temperature. Subsequently, 10BaF2：NaF, Na3AIF6/TiO2 composite photocatalyst is prepared and its catalytic activity is evaluated by the photocatalytic reduction of CO2 under visible light irradiation （λ〉 515 nm）. The results show that 10BaF2：NaF, Na3AIF6/TiO2 is a more effective photocatalyst for CO2 reduction than pure TiO2, their corresponding methanol yields are 179 and 0 μmol/g-cat under the same conditions. Additionally, the mechanism of photocatalytic reduction of CO2 on 10BaF2：NaF, Na3AIF6/TiO2 is proposed.展开更多
文摘The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is highly intriguing and challenging to promote the selectivity and efficiency of visible-light-responsive photocatalysts that favor the adsorption of CO2 in photoreduction processes.In this work,three-dimensional hierarchical Cd0.8Zn0.2S flowers(C8Z2S-F)with ultrathin petals were successfully synthesized through an in-situ self-assembly growth process using sodium citrate as a morphology director.The flower-like Cd0.8Zn0.2S solid solution exhibited remarkable photocatalytic performance in the reduction of CO2,generating CO up to 41.4μmol g^−1 under visible-light illumination for 3 h;this was nearly three times greater than that of Cd0.8Zn0.2S nanoparticles(C8Z2S-NP)(14.7μmol g^−1).Particularly,a comparably high selectivity of 89.9%for the conversion of CO2 to CO,with a turnover number of 39.6,was obtained from the solar-driven C8Z2S-F system in the absence of any co-catalyst or sacrificial agent.Terahertz time-domain spectroscopy indicated that the introduction of flower structures enhanced the light-harvesting capacity of C8Z2S-F.The in situ diffuse reflectance infrared Fourier transform spectroscopy unveiled the existence of surface-adsorbed species and the conversion of photoreduction intermediates during the photocatalytic process.Empirical characterizations and predictions of the photocatalytic mechanism demonstrated that the flower-like Cd0.8Zn0.2S solid solution possessed desirable CO2 adsorption properties and an enhanced charge-transfer capability,thus providing a highly effective photocatalytic reduction of CO2.
基金supported by the National Key R&D Program of China (2017YFA0207301)National Natural Science Foundation of China (No.21725102, No.21471141,No.21601173)+3 种基金CAS Key Research Program of Frontier Sciences(QYZDB-SSWSLH018)CAS Interdisciplinary Innovation Team,Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology (No.2016FXCX003)Anhui Provincial Natural Science Foundation (No.1608085QB24)Chinese Universities Scientific Fund (WK2310000067)
文摘Photocatalytic reduction of CO2 into various types of fuels has attracted great interest,and serves as a potential solution to addressing current global warming and energy challenges.In this work,Ag-Cu nanoparticles are densely supported on N-doped TiO2 nanowire through a straightforward nanofabrication approach.The range of light absorption by N-doped TiO2 can be tuned to match the plasmonic band of Ag nanoparticles,which allows synergizing a resonant energy transfer process with the Schottky junction.Meanwhile,Cu nanoparticles can provide active sites for the reduction of CO2 molecules.Remarkably,the performance of photocatalytic CO2 reduction is improved to produce CH4 at a rate of 720μmol·g-1·h-1 under full-spectrum irradiation.
基金financial support from the National Key Projects for Fundamental Research and Development of China (2016YFB0600901, 2017YFA0206904, 2017YFA0206900, 2018YFB1502002)the National Natural Science Foundation of China (51825205, 51772305, 51572270, U1662118, 21871279, 21802154, 21902168)+10 种基金the Beijing Natural Science Foundation (2191002, 2182078, 2194089)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB17000000)the Royal Society-Newton Advanced Fellowship (NA170422)the International Partnership Program of Chinese Academy of Sciences (GJHZ1819, GJHZ201974)the Beijing Municipal Science and Technology Project (Z181100005118007)the K. C. Wong Education Foundationthe Young Elite Scientist Sponsorship Program by CAST (YESS)the Youth Innovation Promotion Association of the CASthe Energy Education Trust of New Zealandthe Mac Diarmid Institute for Advanced Materials and Nanotechnologythe Dodd Walls Centre for Photonic and Quantum Technologies。
文摘Photocatalytic CO2 reduction holds promise as a future technology for the manufacture of fuels and commodity chemicals.However,factors controlling product selectivity remain poorly understood.Herein,we compared the performance of a homologous series of Zn-based layered double hydroxide(ZnM-LDH)photocatalysts for CO2 reduction.By varying the trivalent or tetravalent metal cations in the ZnM-LDH photocatalysts(M=Ti4+,Fe3+,Co3+,Ga3+,Al3+),the product selectivity of the reaction could be precisely controlled.ZnTi-LDH afforded CH4 as the main reduction product;ZnFe-LDH and ZnCo-LDH yielded H2 exclusively from water splitting;whilst ZnGa-LDH and ZnAl-LDH generated CO.In-situ diffuse reflectance infrared measurements,valence band XPS and density function theory calculations were applied to rationalize the CO2 reduction selectivities of the different ZnM-LDH photocatalysts.The analyses revealed that the d-band center(ed)position of the M3+or M4+cations controlled the adsorption strength of CO2 and thus the selectivity to carbon-containing products or H2.Cations with d-band centers relatively close to the Fermi level(Ti4+,Ga3+and Al3+)adsorbed CO2 strongly yielding CH4 or CO,whereas metal cations with d-band centers further from the Fermi level(Fe3+and Co3+)adsorbed CO2 poorly,thereby yielding H2 only(from water splitting).Our findings clarify the role of trivalent and tetravalent metal cations in LDH photocatalysts for the selective CO2 reduction,paving new ways for the development of improved LDH photocatalyst with high selectivities to specific products.
文摘Photocatalytic CO2 reduction on metal-oxide-based catalysts is promising for solving the energy and environmental crises faced by mankind. The oxygen vacancy （Vo） on metal oxides is expected to be a key factor affecting the efficiency of photocatalytic CO2 reduction on metal-oxide-based catalysts. Yet, to date, the question of how an Vo influences photocatalytic CO2 reduction is still unanswered. Herein, we report that, on Vo-rich gallium oxide coated with Pt nanoparticles （Vo-rich Pt/Ga203）, CO2 is photocatalytically reduced to CO, with a highly enhanced CO evolution rate （21.0umol.h-1） compared to those on Vo-poor Pt/Ga2O3 （3.9 gmol-h-1） and Pt/TiO2（P25） （6.7 gmol.h-1）. We demonstrate that the Vo leads to improved CO2 adsorption and separation of the photoinduced charges on Pt/Ga203, thus enhancing the photocatalytic activity of Pt/Ga203. Rational fabrication of an Vo is thereby an attractive strategy for developing efficient catalysts for photocatalytic CO2 reduction.
文摘Metal nanoparticle （NP） co-catalysts on metal oxide semiconductor supports are attracting attention as photocatalysts for a variety of chemical reactions. Related efforts seek to make and use Pt-free catalysts. In this regard, we report here enhanced CH4 formation rates of 25 and 60 μmol·g^-1·h^-1 by photocatalytic CO2 reduction using hitherto unused ZnPd NPs as well as Au and Ru NPs. The NPs are formed by colloidal synthesis and grafted onto short n-type anatase TiO2 nanotube arrays （TNAs）, grown anodically on transparent glass substrates. The interfacial electric fields in the NP-grafted TiO2 nanotubes were probed by ultraviolet photoelectron spectroscopy （UPS）. Au NP-grafted TiO2 nanotubes （Au-TNAs） showed no band bending, but a depletion region was detected in Ru NP-grafted TNAs （Ru-TNAs） and an accumulation layer was observed in ZnPd NP-grafted TNAs （ZnPd-TNAs）. Temperature programmed desorption （TPD） experiments showed significantly greater CO2 adsorption on NP-grafted TNAs. TNAs with grafted NPs exhibit broader and more intense UV-visible absorption bands than bare TNAs. We found that CO2 photoreduction by nanoparticle-grafted TNAs was driven not only by ultraviolet photons with energies greater than the TiO2 band gap, but also by blue photons close to and below the anatase band edge. The enhanced rate of CO2 reduction is attributed to superior use of blue photons in the solar spectrum, excellent reactant adsorption, efficient charge transfer to adsorbates, and low recombination losses.
基金supported by the National Basic Research Program of China(973 Program2013CB632402)+7 种基金the National Natural Science Foundation of China(513201050015137219051402025and 21433007)the Natural Science Foundation of Hubei Province(2015CFA001)the Fundamental Research Funds for the Central Universities(WUT:2014-VII-010)the Self-Determined and Innovative Research Funds of State Key Laboratory of Advanced Technology for Material Synthesis and ProcessingWuhan University of Technology(2013-ZD-1)~~
文摘Nitrogen-doped anatase TiO 2 microsheets with 65%（001） and 35%（101） exposed faces were fabricated by the hydrothermal method using TiN as precursor in the presence of HF and HCl. The samples were characterized by scanning electron microscopy,X-ray diffraction,N2 adsorption,X-ray photoelectron spectroscopy,UV-visible spectroscopy,and electrochemical impedance spectroscopy. Their photocatalytic activity was evaluated using the photocatalytic reduction of CO2. The N-doped TiO 2 sample exhibited a much higher visible light photocatalytic activity for CO2 reduction than its precursor TiN and commercial TiO 2（P25）. This was due to the synergistic effect of the formation of surface heterojunctions on the TiO 2 microsheet surface,enhanced visible light absorption by nitrogen-doping,and surface fluorination.
基金financially supported by the National Natural Science Foundation of China(NSFC)(Nos.51872220,51932007,51961135303,21871217,U1905215 and U1705251)the National Key Research and Development Program of China(No.2018YFB1502001)the Fundamental Research Funds for the Central Universities(No.WUT:2019IVB050)。
文摘Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow microspheres(HS),were dedicatedly designed to boost overall photocatalytic efficiency.TiO_(2) nanoparticles were in-situ decorated on the inside and outside the shell of Cd S HS,ensuring close contact between TiO_(2) and CdS.The CdS/TiO2 HS with abundant mesopores inside of the shell boost the light absorption via multiscattering effect as well as accessible to reactions in all directions.The heterojunction was scrutinized and the charge transfer across it was revealed by in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS).Ultimately,the charge transfer in this composite was determined to follow stepscheme mechanism,which not only facilitates the separation of charge carriers but also preserves strong redox ability.Benefited from the intimate linkage between Cd S and TiO_(2) and the favorable step-scheme heterojunction,enhanced photocatalytic CO_(2) reduction activity was accomplished.The CH4 yield rate of CdS/TiO_(2) reaches 27.85μmol g^(–1) h^(–1),which is 145.6 and 3.8 times higher than those of pristine CdS and TiO_(2),respectively.This work presents a novel insight into constructing step-scheme photocatalytic system with desirable performance.
文摘The active site amount of photocatalysts,being the key factors in photocatalytic reactions,directly affects the photocatalytic performance of the photocatalyst.Pristine graphitic carbon nitride(g‐C_(3)N_(4))exhibits moderate photocatalytic activity due to insufficient active sites.In this study,cyano‐modified porous g‐C_(3)N_(4)nanosheets(MCN‐0.5)were synthesized through molecular self‐assembly and alkali‐assisted strategies.The cyano group acted as the active site of the photocatalytic reaction,because the good electron‐withdrawing property of the cyano group promoted carrier separation.Benefiting from the effect of the active sites,MCN‐0.5 exhibited significantly enhanced photocatalytic activity for CO2 reduction under visible light irradiation.Notably,the photocatalytic activity of MCN‐0.5 was significantly reduced when the cyano groups were removed by hydrochloric acid(HCl)treatment,further verifying the role of cyano groups as active sites.The photoreduction of Pt nanoparticles provided an intuitive indication that the introduction of cyano groups provided more active sites for the photocatalytic reaction.Furthermore,the controlled experiments showed that g‐C_(3)N_(4)grafted with cyano groups using melamine as the precursor exhibited enhanced photocatalytic activity,which proved the versatility of the strategy for enhancing the activity of g‐C_(3)N_(4)via cyano group modification.In situ diffuse reflectance infrared Fourier transform spectroscopy and theoretical calculations were used to investigate the mechanism of enhanced photocatalytic activity for CO2 reduction by cyano‐modified g‐C_(3)N_(4).This work provides a promising route for promoting efficient solar energy conversion by designing active sites in photocatalysts.
文摘Crystalline TiO（P25） and isolated titanate species in a ZSM-5 structure（TS-1） were modified with Au and Ag, respectively, and tested in the gas-phase photocatalytic COreduction under high purity conditions. The noble metal modification was performed by photodeposition. Light absorbance properties of the catalysts are examined with UV–Vis spectroscopy before and after the activity test. In the gas-phase photocatalytic COreduction, it was observed that the catalysts with Ag nanostructures are more active than those with Au nanostructures. It is thus found that the energetic difference between the band gap energy of the semiconductor and the position of the plasmon is influencing the photocatalytic activity.Potentially, plasmon excitation due to visible light absorption results in plasmon resonance energy, which affects the excitation of the semiconductor positively. Therefore, an overlap between band gap energy of the semiconductor and metal plasmon is needed.
基金supported by the National Natural Science Foundation of China (51961135303, 51932007, 21871217 and U1705251)the National Key Research and Development Program of China (2018YFB1502001)Innovative Research Funds of SKLWUT (2017-ZD-4)
文摘Hierarchical heterostructure photocatalysts with broad spectrum solar light utilization,particularly in the nearinfrared(NIR)region,are emerging classes of advanced photocatalytic materials for solar-driven CO2 conversion into value-added chemical feedstocks.Herein,a novel two-demensional/three-demensional(2 D/3 D)hierarchical composite is hydrothermally synthesized by assembling vertically-aligned ZnIn2 S4(ZIS)nanowall arrays on nitrogen-doped graphene foams(NGF).The prepared ZIS/NGF composite shows enhancement in photothermal conversion ability and selective CO2 capture as well as solar-driven CO2 photoreduction.At273 K and 1 atm,the ZIS/NGF composite with 1.0 wt%NGF achieves a comparably high CO2-to-N2 selectivity of 30.1,with an isosteric heat of CO2 adsorption of 48.2 kJ mol^-1.And in the absence of cocatalysts and sacrificial agents,the ZIS/NGF composite with cyclability converts CO2 into CH4,CO and CH3 OH under simulated solar light illumination,with the respective evolution rates about 9.1,3.5,and 5.9 times higher than that of the pristine ZIS.In-depth analysis using in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS)in conjunction with Kelvin probe measurements reveals the underlying charge transfer pathway and process from ZIS to NGF.
基金financially supported by the National Natural Science Foundation of China(51872341,51572209)the Start-up Funds for High-Level Talents of Sun Yat-sen University(38000-31131105)+1 种基金the Fundamental Research Funds for the Central Universities(19lgzd29)the Science and Technology Program of Guangzhou(201707010095)~~
文摘Although both the aerobic photocatalytic oxidation of organic pollutants into CO2 and the anaerobic photocatalytic reduction of CO2 into solar fuels have been intensively studied,few efforts have been devoted to combining these carbon-involved photocatalytic oxidation-reduction processes together,by which an artificial photocatalytic carbon cycling process can be established.The key challenge lies in the exploitation of efficient bifunctional photocatalysts,capable of triggering both aerobic oxidation and anaerobic reduction reactions.In this work,a bifunctional ternary g-C3N4/Bi/BiVO4 hybrid photocatalyst is successfully constructed,which not only demonstrates superior aerobic photocatalytic oxidation performance in degrading an organic pollutant(using the dye,Rhodamine B as a model),but also exhibits impressive photocatalytic CO2 reduction performance under anaerobic conditions.Moreover,a direct conversion of Rhodamine B to solar fuels in a one-pot anaerobic reactor can be achieved with the as-prepared ternary g-C3N4/Bi/BiVO4 hybrid photocatalyst.The excellent bifunctional photocatalytic performance of the g-C3N4/Bi/BiVO4 photocatalyst is associated with the formation of efficient S-scheme hybrid junctions,which contribute to promoting the appropriate charge dynamics,and sustaining favorable charge potentials.The formation of the S-scheme heterojunction is supported by scavenger studies and density functional theory calculations.Moreover,the in-situ formed plasmonic metallic Bi nanoparticles in the S-scheme hybrid g-C3N4/Bi/BiVO4 photocatalyst enhances vectorial interfacial electron transfer.This novel bifunctional S-scheme g-C3N4/Bi/BiVO4 hybrid photocatalyst system provides new insights for the further development of an integrated aerobic-anaerobic reaction system for photocatalytic carbon cycling.
基金supported by the National Basic Research Program of China(2013CB632402)the National Natural Science Foundation of China(51320105001,21433007,51372190,21573170)+3 种基金the Natural Science Foundation of Hubei Province(2015CFA001)the Fundamental Research Funds for the Central Universities(WUT:2015-III-034)Innovative Research Funds of SKLWUT(2017-ZD-4)the Discovery Early Career Researcher Award(DECRA)by Australian Research Council(DE160101488)
文摘Hierarchically nanostructured, porous TiO_2(B) microspheres were synthesized by a microwave-assisted solvothermal method combined with subsequent heat treatment in air. The materials were carefully characterized by scanning and transmission electron microscopy, X-ray diffraction, CO_2 adsorption, and a range of spectroscopies, including Raman, infrared, X-ray photoelectron and UV-Vis spectroscopy. The hierarchical TiO_2(B) particles are constructed by ultrathin nanosheets and possess large specific surface area, which provided many active sites for CO_2 adsorption as well as CO_2 conversion. The TiO_2(B)nanostructures exhibited marked photocatalytic activity for CO_2 reduction to methane and methanol. Anatase TiO_2 and P25 were used as the reference photocatalysts. Transient photocurrent measurement also proved the higher photoactivity of TiO_2(B) than that of anatase TiO_2. In-situ infrared spectrum was measured to identify the intermediates and deduce the conversion process of CO_2 under illumination over TiO_2(B) photocatalyst.
基金supported by the National Natural Science Foundation of China (Grant No. 20876125)the Research Fund for the Doctoral Program of Higher Education, China (Grant No. 20096101110013)the Northwest University Graduate Interdisciplinary Funds, China (Grant Nos. 09YJC24 and 09YJC27)
文摘A rare-earth free upconversion luminescent material, 10BaF2：NaF, Na3AIF6, is synthesized by a hydrothermal method. The study of fluorescent spectrum indicates that it can convert visible light （550 nm-610 nm） into ultraviolet light （290 nm 350 nm）, and two emission peaks at 304 nm and 324 nm are observed under the excitation of 583 nm at room temperature. Subsequently, 10BaF2：NaF, Na3AIF6/TiO2 composite photocatalyst is prepared and its catalytic activity is evaluated by the photocatalytic reduction of CO2 under visible light irradiation （λ〉 515 nm）. The results show that 10BaF2：NaF, Na3AIF6/TiO2 is a more effective photocatalyst for CO2 reduction than pure TiO2, their corresponding methanol yields are 179 and 0 μmol/g-cat under the same conditions. Additionally, the mechanism of photocatalytic reduction of CO2 on 10BaF2：NaF, Na3AIF6/TiO2 is proposed.
