TiO2 nanosheets mainly exposed （001） facet were prepared through a hydrothermal process with HF as the morphology-directing agent. Ru and RuO2 species were loaded by photo-deposition methods to prepare the photocata...TiO2 nanosheets mainly exposed （001） facet were prepared through a hydrothermal process with HF as the morphology-directing agent. Ru and RuO2 species were loaded by photo-deposition methods to prepare the photocatalysts. The structural features of the catalysts were characterized by X-ray di raction, transmission electron microscopy, inductively cou-pled plasma atomic emission spectrum, and H2 Temperature-programmed reduction. The photocatalytic property was studied by the O2 evolution from water oxidation, which was examined with respect to the in uences of Ru contents as well as the oxidation and reduction treatments, suggesting the charge separation effect of the Ru species co-catalysts on di erent facets of TiO2 nanosheets. In contrast to Ru/TiO2 and RuO2/TiO2 with the single deposited co-catalyst, the optimized catalyst 0.5%Ru-1.0%RuO2/TiO2 with dual co-catalysts achieved a much improved catalytic performance, in terms of the synergetic effect of dual co-catalysts and the enhanced charge separation effect.展开更多
Herein, novel plasmonic Bi metal in situ deposited in reduced Ti O2 microspheres(Bi@R-Ti O2) are fabricated via a bimetallic MOF-derived synthesized strategy by adjusting the synthesizing temperature. Different charac...Herein, novel plasmonic Bi metal in situ deposited in reduced Ti O2 microspheres(Bi@R-Ti O2) are fabricated via a bimetallic MOF-derived synthesized strategy by adjusting the synthesizing temperature. Different characterization techniques, including XRD, SEM, TEM, XPS, DRS, PL, EIS, and photocurrent generation, are performed to investigate the structural and optical properties of the as-prepared samples. The results indicate that the Bi particles are generated inside and outside of reduced Ti O2 microspheres via the reduction of Ti4+ and Bi3+ by ethylene glycol. When the annealing temperature is controlled at 300 o C, the corresponding Bi@R-Ti O2-300 sample with an appropriate amount of Bi nanoparticles exhibits the highest full solar spectrum photocatalytic oxygen evolution activity(4728.709 μmol h–1 g–1), which is 5.9 and 9.5 times higher than that of pure Ti O2 and Bi-Ti bimetal organic frameworks(Bi-Ti-MOFs). Several reasons are suggested for the above results:(1) Bi metal behaves as an "electron acceptor" to accelerate the charge carrier transfer from Ti O2 to Bi;(2) The surface plasmon resonance effect of loaded metallic Bi particles can enhance the visible and NIR light absorption capacity;(3) The generation of Ti3+ further narrows the band gap of TiO2.展开更多
A spinel oxide NiCo204 prepared by thermal decomposition is of very high activity for the oxygen evolution reaction(OER)in alkaline solution.The oxygen evolution overpotential on NiCo204 is 0.252-0.262V in 10 M NaOH s...A spinel oxide NiCo204 prepared by thermal decomposition is of very high activity for the oxygen evolution reaction(OER)in alkaline solution.The oxygen evolution overpotential on NiCo204 is 0.252-0.262V in 10 M NaOH solution at 343K and current density 100 mAcm^(-2).展开更多
Attempts were made to culture Spirulina platensis in human urine directly to achieve biomass production and O2 evolution, for potential application to nutrient regeneration and air revitalization in life support syste...Attempts were made to culture Spirulina platensis in human urine directly to achieve biomass production and O2 evolution, for potential application to nutrient regeneration and air revitalization in life support system. The culture results showed that Spirulinaplatensis grows successfully in diluted human urine, and yields maximal biomass at urine dilution ratios of 140-240. Accumulation of lipid and decreasing of protein occurred due to N deficiency. O2 release rate of Spirulina platensis in diluted human urine was higher than that in Zarrouk medium.展开更多
TiO2 photocatalysts loaded with V2O5 were prepared via a modified hydrolysis process,and characterized by X-ray diffraction,transmission electron microscopy,Raman spectra and diffuse reflectance UV-Vis spectra measure...TiO2 photocatalysts loaded with V2O5 were prepared via a modified hydrolysis process,and characterized by X-ray diffraction,transmission electron microscopy,Raman spectra and diffuse reflectance UV-Vis spectra measurements. The photocatalytic activity of V2O5/TiO2 was investigated by employing splitting of water for O2 evolution. The results indicate that V2O5 loading can pronouncedly improve the photocatalytic activity of TiO2 with Fe3+ as an electron acceptor under UV or visible light irradiation. The optimum mass fraction of the loaded V2O5 is 8%,and the largest speed of O2 evolution for 8%V2O5 (mass fraction) loaded TiO2 catalyst is 118.2 μmol/(L.h) under UV irradiation,and 83.7 μmol/(L.h) under visible light irradiation.展开更多
The extruded protoplasm from the coenocytic green alga,Bryopsis hypnoides Lamouroux,was able to reform a cell wall and develop further into a mature alga in seawater.In this paper,the influence of albumen on the abili...The extruded protoplasm from the coenocytic green alga,Bryopsis hypnoides Lamouroux,was able to reform a cell wall and develop further into a mature alga in seawater.In this paper,the influence of albumen on the ability of aggregation and on the photosynthesis of protoplasm was examined.Results show that the protoplasm of B.hypnoides could aggregate in either albumen or chicken egg,which is similar to that in seawater.However unlike in seawater,the aggregation from B.hypnoides in albumen and chicken egg failed to develop into a mature individual.Interestingly,the protoplasm of B.hypnoides could maintain its photosynthetic O_2 evolution in albumen and chicken egg,while the time in chicken egg was longer than that in albumen.展开更多
A novel series of photocatalysts, bismuth oxyhalide （BiOX, X = Cl, Br, and Ⅰ）, were synthesized by a hydrolysis method. The powder sampies were characterized by the use of X-ray diffraction （XRD）, scanning electr...A novel series of photocatalysts, bismuth oxyhalide （BiOX, X = Cl, Br, and Ⅰ）, were synthesized by a hydrolysis method. The powder sampies were characterized by the use of X-ray diffraction （XRD）, scanning electron microscope, and UV-Vis spectrophotometer. The XRD pattern showed that all the BiOX were well crystallized in the tetragonal structure. The band gaps of the sheet-shaped compounds BiOX （X = Cl, Br, andⅠ） were 3.44, 2.76, and 1.85 eV, respectively. BiOBr showed the highest photocatalytic activity in degrading rhodamine B （RhB） and evolving 02 for its proper valence band （VB）. BiOI has no photocatalytic activity. BiOCl showed the highest activity in decomposing isopropanol because of electron-hole pair separation through trapping electrons by oxygen vacancies.展开更多
Photocatalytic water oxidation for O2evolution is known as a bottle neck in water splitting.Various strategies have been conducted to keep the energetics of photogenerated holes or to create more holes in the bulk to ...Photocatalytic water oxidation for O2evolution is known as a bottle neck in water splitting.Various strategies have been conducted to keep the energetics of photogenerated holes or to create more holes in the bulk to reach the surface for efficient photocatalytic water oxidation.Our previous study demonstrated the effectiveness of interstitial boron doping in improving photocatalytic water oxidation by lowering the valence band maximum of TiO2with a concentration gradient of boron.In this study,homogeneous doping of interstitial boron was realized in a TiO2shell with mixed anatase/rutile phases that was produced by the gaseous hydrolysis of the surface layer of TiB2crystals in a moist argon atmosphere.Consequently,the homogeneous doping and lowered valence band maximum improved the energetics of holes for efficient photocatalytic water oxidation.展开更多
Green reactions not only provide us chemical products without any pollution,but also offer us the viable technology to realize difficult tasks in normal conditions.Photo-,photoelectro-,and electrocatalytic reactions a...Green reactions not only provide us chemical products without any pollution,but also offer us the viable technology to realize difficult tasks in normal conditions.Photo-,photoelectro-,and electrocatalytic reactions are indeed powerful tools to help us to embrace bright future.Especially,some gas-involved reactions are extremely useful to change our life environments from energy systems to liquid fuels and cost-effective products,such as H2 evolution(H2 production),02 evolution/reduction,CO2 reduction,N2 reduction(or N2 fixation) reactions.We can provide fuel cells clean H2 for electric vehicles from H2 evolution reaction(HER),at the same time,we also need highly efficient 02 reduction reaction(ORR) in fuel cells for improving the reaction kinetics.Moreover,we can get the clean oxidant O2 from water through O2 evolution reaction(OER),and carry out some reactions without posing any pollution to reaction systems.Furthermore,we can translate the greenhouse gas CO2 into useful liquid fuels through CO2 reduction reaction(CRR).Last but not the least,we can get ammonia from N2 reduction reaction(NRR),which can decrease energy input compared to the traditional Hubble process.These reactions,such as HER,ORR,OER,CRR and NRR could be realized through solar-,photoelectro-and electro-assisted ways.For them,the catalysts used play crucial roles in determining the efficiency and kinds of products,so we should consider the efficiency of catalysts.However,the cost,synthetic methods of catalysts should also be considered.Nowadays,significant progress has been achieved,however,many challenges still exist,reaction systems,catalysts underlying mechanisms,and so on.As extremely active fields,we should pay attention to them.Under the background,it has motivated us to contribute with a roadmap on ’GasInvolved Photo-and Electro-Catalysis’.展开更多
Fe based oxides are considered as a promising catalyst for the oxygen evolution reaction （OER） due to their low cost and high stability. Here, based on density functional theory calculations, the electrocatalytic be...Fe based oxides are considered as a promising catalyst for the oxygen evolution reaction （OER） due to their low cost and high stability. Here, based on density functional theory calculations, the electrocatalytic behaviors of pure and metal （Ni, Co） doped Fe-terminated Fe2O3（0001） are investigated. The potential-limiting step for OER is determined as the formation of O＊ by dehydrogenating surface hydroxyl and it is suggested that the doping enhances the catalytic activity of Fe2O3（0001） by reducing the free energy change of rate limiting step on doped Ni or Co atom. Especially, the calculated over-potential of Co-doped Fe2O3 （0001） surface is about 0.63 eV on Co site, which is comparable with the theoretical over-potential of 0.56 eV for RuO2.展开更多
Here, PbCrO4 nanorods, a commonly used and low-cost yellow pigment, was synthesized via a simple pre-cipitation reaction and can serve as a highly efficient oxygen production and photodegradation photocatalyst. The ob...Here, PbCrO4 nanorods, a commonly used and low-cost yellow pigment, was synthesized via a simple pre-cipitation reaction and can serve as a highly efficient oxygen production and photodegradation photocatalyst. The obtained PbCrO4 nanorods exhibit excellent stability and pho-tocatalytic performance for O2 evolution from water. The production rate is approximately 314.0μmol h^-1 g^-1 under visible light, and the quantum efficiency is approximately 2.16% at 420±10 nm and 0.05% at 600±10 nm. In addition, the PhCrO4 shows good degradation performance for methylene blue, methyl blue, methyl orange and phenol under visible-light irradiation. These results indicate that it is potential to fabricate an effective, robust PbCrO4 photocatalyst by trans-forming heavy-metal pollutants Pb（II） and Cr（VI） into a highly efficient O2 evolution and photodegradation material. This strategy which uses pollutant to produce clean energy and degrade contaminants is completely green and environmentally benign, and thus could be a promising way for practical environmental applications. Keywords： 02 evolution, pollutant, PbCrO4 nanorods, visible-light-active, photocatalyst展开更多
The development of visible-light-responsive photocatalysts for promoting solar-driven oxygen(O2)production from water splitting is a potentially attractive but still a challenging scheme.In the present work,a(111)-typ...The development of visible-light-responsive photocatalysts for promoting solar-driven oxygen(O2)production from water splitting is a potentially attractive but still a challenging scheme.In the present work,a(111)-type layered perovskite oxynitride,Sr5Nb4O15-xNx,was synthesized via the nitridation treatment of the disk-like oxide precursor under the ammonia flow,which was fabricated using a flux method.The homogeneous dispersion of nitrogen(N)dopant in N-doped Sr5Nb4O15 was ascertained by energy-dispersive X-ray spectroscopy characterization,and the Sr5Nb4O15-xNx was found to be a direct semiconductor with a light absorption edge of approximately 640 nm.Density functional theory investigation implies that the hybridization between the outmost N 2p orbitals and O 2p orbitals upshifts the original valence band maximum of Sr5Nb4O15 and endows its visible-light-responsive characteristics.Loading with cobalt oxide(CoOx)as cocatalyst,the as-prepared Sr5Nb4O15-xNx exhibited an enhanced photocatalytic O2 evolution activity from water splitting under visible-light illumination(λ>420 nm).Moreover,another homogeneous N-doped layered perovskite-type niobium(Nb)-based oxynitride,Ba5Nb4O15-xNx,was also developed and investigated for the visible-light-actuated O2 production,highlighting the versatility of the present approach for exploring novel visible-light-responsive photocatalysts.展开更多
文摘TiO2 nanosheets mainly exposed （001） facet were prepared through a hydrothermal process with HF as the morphology-directing agent. Ru and RuO2 species were loaded by photo-deposition methods to prepare the photocatalysts. The structural features of the catalysts were characterized by X-ray di raction, transmission electron microscopy, inductively cou-pled plasma atomic emission spectrum, and H2 Temperature-programmed reduction. The photocatalytic property was studied by the O2 evolution from water oxidation, which was examined with respect to the in uences of Ru contents as well as the oxidation and reduction treatments, suggesting the charge separation effect of the Ru species co-catalysts on di erent facets of TiO2 nanosheets. In contrast to Ru/TiO2 and RuO2/TiO2 with the single deposited co-catalyst, the optimized catalyst 0.5%Ru-1.0%RuO2/TiO2 with dual co-catalysts achieved a much improved catalytic performance, in terms of the synergetic effect of dual co-catalysts and the enhanced charge separation effect.
基金the National Natural Science Foundation of China(51872173 and 51772176)Taishan Scholarship of Young Scholars(tsqn201812068)+2 种基金Natural Science Foundation of Shandong Province(ZR2017JL020)Taishan Scholarship of Climbing Plan(tspd20161006)Key Research and Development Program of Shandong Province(2018GGX102028)~~
文摘Herein, novel plasmonic Bi metal in situ deposited in reduced Ti O2 microspheres(Bi@R-Ti O2) are fabricated via a bimetallic MOF-derived synthesized strategy by adjusting the synthesizing temperature. Different characterization techniques, including XRD, SEM, TEM, XPS, DRS, PL, EIS, and photocurrent generation, are performed to investigate the structural and optical properties of the as-prepared samples. The results indicate that the Bi particles are generated inside and outside of reduced Ti O2 microspheres via the reduction of Ti4+ and Bi3+ by ethylene glycol. When the annealing temperature is controlled at 300 o C, the corresponding Bi@R-Ti O2-300 sample with an appropriate amount of Bi nanoparticles exhibits the highest full solar spectrum photocatalytic oxygen evolution activity(4728.709 μmol h–1 g–1), which is 5.9 and 9.5 times higher than that of pure Ti O2 and Bi-Ti bimetal organic frameworks(Bi-Ti-MOFs). Several reasons are suggested for the above results:(1) Bi metal behaves as an "electron acceptor" to accelerate the charge carrier transfer from Ti O2 to Bi;(2) The surface plasmon resonance effect of loaded metallic Bi particles can enhance the visible and NIR light absorption capacity;(3) The generation of Ti3+ further narrows the band gap of TiO2.
文摘A spinel oxide NiCo204 prepared by thermal decomposition is of very high activity for the oxygen evolution reaction(OER)in alkaline solution.The oxygen evolution overpotential on NiCo204 is 0.252-0.262V in 10 M NaOH solution at 343K and current density 100 mAcm^(-2).
基金Project (No. 10376032) supported by the National Nature Science Associate Fundation (NSAF) of China
文摘Attempts were made to culture Spirulina platensis in human urine directly to achieve biomass production and O2 evolution, for potential application to nutrient regeneration and air revitalization in life support system. The culture results showed that Spirulinaplatensis grows successfully in diluted human urine, and yields maximal biomass at urine dilution ratios of 140-240. Accumulation of lipid and decreasing of protein occurred due to N deficiency. O2 release rate of Spirulina platensis in diluted human urine was higher than that in Zarrouk medium.
基金Project(08JJ3022) supported by the Natural Science Foundation of Hunan Province, China
文摘TiO2 photocatalysts loaded with V2O5 were prepared via a modified hydrolysis process,and characterized by X-ray diffraction,transmission electron microscopy,Raman spectra and diffuse reflectance UV-Vis spectra measurements. The photocatalytic activity of V2O5/TiO2 was investigated by employing splitting of water for O2 evolution. The results indicate that V2O5 loading can pronouncedly improve the photocatalytic activity of TiO2 with Fe3+ as an electron acceptor under UV or visible light irradiation. The optimum mass fraction of the loaded V2O5 is 8%,and the largest speed of O2 evolution for 8%V2O5 (mass fraction) loaded TiO2 catalyst is 118.2 μmol/(L.h) under UV irradiation,and 83.7 μmol/(L.h) under visible light irradiation.
基金Supported by the National Natural Science Foundation of China (No.30830015)the Project of Supporting the National Development (No.2006BAD09A04)and the National High Technology and Development Program of China (863 Program) (Nos.2006AA 10A402,2007AA09Z406,2006AA05Z112,2006AA10A413)
文摘The extruded protoplasm from the coenocytic green alga,Bryopsis hypnoides Lamouroux,was able to reform a cell wall and develop further into a mature alga in seawater.In this paper,the influence of albumen on the ability of aggregation and on the photosynthesis of protoplasm was examined.Results show that the protoplasm of B.hypnoides could aggregate in either albumen or chicken egg,which is similar to that in seawater.However unlike in seawater,the aggregation from B.hypnoides in albumen and chicken egg failed to develop into a mature individual.Interestingly,the protoplasm of B.hypnoides could maintain its photosynthetic O_2 evolution in albumen and chicken egg,while the time in chicken egg was longer than that in albumen.
基金This study was financially supported by the National Natural Science Foundation of China(No.50471004)the Program for New Century Excellent Talents in Universities,and the Foundation from Engineering Research Institute,Peking University(No.204031)
文摘A novel series of photocatalysts, bismuth oxyhalide （BiOX, X = Cl, Br, and Ⅰ）, were synthesized by a hydrolysis method. The powder sampies were characterized by the use of X-ray diffraction （XRD）, scanning electron microscope, and UV-Vis spectrophotometer. The XRD pattern showed that all the BiOX were well crystallized in the tetragonal structure. The band gaps of the sheet-shaped compounds BiOX （X = Cl, Br, andⅠ） were 3.44, 2.76, and 1.85 eV, respectively. BiOBr showed the highest photocatalytic activity in degrading rhodamine B （RhB） and evolving 02 for its proper valence band （VB）. BiOI has no photocatalytic activity. BiOCl showed the highest activity in decomposing isopropanol because of electron-hole pair separation through trapping electrons by oxygen vacancies.
基金supported by the National Science Foundation of China (51702327, 51521091)the Major Basic Research Program, Ministry of Science and Technology of China (2014CB239401)+2 种基金the Key Research Program of Frontier Sciences CAS (QYZDB-SSW-JSC039)the awards of the IMR SYNL-T.S. Kê Research Fellowship the Newton Advanced Fellowship~~
文摘Photocatalytic water oxidation for O2evolution is known as a bottle neck in water splitting.Various strategies have been conducted to keep the energetics of photogenerated holes or to create more holes in the bulk to reach the surface for efficient photocatalytic water oxidation.Our previous study demonstrated the effectiveness of interstitial boron doping in improving photocatalytic water oxidation by lowering the valence band maximum of TiO2with a concentration gradient of boron.In this study,homogeneous doping of interstitial boron was realized in a TiO2shell with mixed anatase/rutile phases that was produced by the gaseous hydrolysis of the surface layer of TiB2crystals in a moist argon atmosphere.Consequently,the homogeneous doping and lowered valence band maximum improved the energetics of holes for efficient photocatalytic water oxidation.
基金The financial support from the National Natural Science Foundation of China (Nos. 51772312, 21671197)
文摘Green reactions not only provide us chemical products without any pollution,but also offer us the viable technology to realize difficult tasks in normal conditions.Photo-,photoelectro-,and electrocatalytic reactions are indeed powerful tools to help us to embrace bright future.Especially,some gas-involved reactions are extremely useful to change our life environments from energy systems to liquid fuels and cost-effective products,such as H2 evolution(H2 production),02 evolution/reduction,CO2 reduction,N2 reduction(or N2 fixation) reactions.We can provide fuel cells clean H2 for electric vehicles from H2 evolution reaction(HER),at the same time,we also need highly efficient 02 reduction reaction(ORR) in fuel cells for improving the reaction kinetics.Moreover,we can get the clean oxidant O2 from water through O2 evolution reaction(OER),and carry out some reactions without posing any pollution to reaction systems.Furthermore,we can translate the greenhouse gas CO2 into useful liquid fuels through CO2 reduction reaction(CRR).Last but not the least,we can get ammonia from N2 reduction reaction(NRR),which can decrease energy input compared to the traditional Hubble process.These reactions,such as HER,ORR,OER,CRR and NRR could be realized through solar-,photoelectro-and electro-assisted ways.For them,the catalysts used play crucial roles in determining the efficiency and kinds of products,so we should consider the efficiency of catalysts.However,the cost,synthetic methods of catalysts should also be considered.Nowadays,significant progress has been achieved,however,many challenges still exist,reaction systems,catalysts underlying mechanisms,and so on.As extremely active fields,we should pay attention to them.Under the background,it has motivated us to contribute with a roadmap on ’GasInvolved Photo-and Electro-Catalysis’.
基金This work was supported by the National Natural Science Foundation of China （No.21573204, No.21421063, No.21473167, No.51172223）, the Ministry of Science and Technology （2016YFA0200602）, Strategic Priority Research Program of CAS （XDB01020300）, the Fundamental Research Funds for the Central Universities, National Program for Support of Top-notch Young Professional, and the USTCSCC, SCCAS, Tianjin, and Shanghai Supercomputer Centers.
文摘Fe based oxides are considered as a promising catalyst for the oxygen evolution reaction （OER） due to their low cost and high stability. Here, based on density functional theory calculations, the electrocatalytic behaviors of pure and metal （Ni, Co） doped Fe-terminated Fe2O3（0001） are investigated. The potential-limiting step for OER is determined as the formation of O＊ by dehydrogenating surface hydroxyl and it is suggested that the doping enhances the catalytic activity of Fe2O3（0001） by reducing the free energy change of rate limiting step on doped Ni or Co atom. Especially, the calculated over-potential of Co-doped Fe2O3 （0001） surface is about 0.63 eV on Co site, which is comparable with the theoretical over-potential of 0.56 eV for RuO2.
基金jointly supported by the National Natural Science Foundation of China(21401190)the Science and Technology Project of Research Foundation of China Postdoctoral Science(2017M612710 and 2016M592519)+2 种基金Shenzhen Peacock Plan(827-000059,827-000113 and KQTD2016053112042971)the Science and Technology Planning Project of Guangdong Province(2016B050501005)the Educational Commission of Guangdong Province(2016KCXTD006 and 2016KSTCX126)
文摘Here, PbCrO4 nanorods, a commonly used and low-cost yellow pigment, was synthesized via a simple pre-cipitation reaction and can serve as a highly efficient oxygen production and photodegradation photocatalyst. The obtained PbCrO4 nanorods exhibit excellent stability and pho-tocatalytic performance for O2 evolution from water. The production rate is approximately 314.0μmol h^-1 g^-1 under visible light, and the quantum efficiency is approximately 2.16% at 420±10 nm and 0.05% at 600±10 nm. In addition, the PhCrO4 shows good degradation performance for methylene blue, methyl blue, methyl orange and phenol under visible-light irradiation. These results indicate that it is potential to fabricate an effective, robust PbCrO4 photocatalyst by trans-forming heavy-metal pollutants Pb（II） and Cr（VI） into a highly efficient O2 evolution and photodegradation material. This strategy which uses pollutant to produce clean energy and degrade contaminants is completely green and environmentally benign, and thus could be a promising way for practical environmental applications. Keywords： 02 evolution, pollutant, PbCrO4 nanorods, visible-light-active, photocatalyst
基金the financial support from the National Key R&D Program of China(No.2020YFA0406102)the National Natural Science Foundation of China(Nos.21633009 and 21925206)+2 种基金the International Partnership Program of Chinese Academy of Sciences(No.121421KYSB20190025)the Dalian National Laboratory for Clean Energy(DNL)Cooperation Fund,CAS(No.DNL 201913)the DICP Foundation of Innovative Research(No.DICP I201927)。
文摘The development of visible-light-responsive photocatalysts for promoting solar-driven oxygen(O2)production from water splitting is a potentially attractive but still a challenging scheme.In the present work,a(111)-type layered perovskite oxynitride,Sr5Nb4O15-xNx,was synthesized via the nitridation treatment of the disk-like oxide precursor under the ammonia flow,which was fabricated using a flux method.The homogeneous dispersion of nitrogen(N)dopant in N-doped Sr5Nb4O15 was ascertained by energy-dispersive X-ray spectroscopy characterization,and the Sr5Nb4O15-xNx was found to be a direct semiconductor with a light absorption edge of approximately 640 nm.Density functional theory investigation implies that the hybridization between the outmost N 2p orbitals and O 2p orbitals upshifts the original valence band maximum of Sr5Nb4O15 and endows its visible-light-responsive characteristics.Loading with cobalt oxide(CoOx)as cocatalyst,the as-prepared Sr5Nb4O15-xNx exhibited an enhanced photocatalytic O2 evolution activity from water splitting under visible-light illumination(λ>420 nm).Moreover,another homogeneous N-doped layered perovskite-type niobium(Nb)-based oxynitride,Ba5Nb4O15-xNx,was also developed and investigated for the visible-light-actuated O2 production,highlighting the versatility of the present approach for exploring novel visible-light-responsive photocatalysts.
