Photocatalytic H_(2)production from water splitting is a promising candidate for solving the increasing energy crisis and environmental issues.Herein we report a novel g-C_(3)N_(4)/Ag In_(x)S_(y)S-scheme heterojunctio...Photocatalytic H_(2)production from water splitting is a promising candidate for solving the increasing energy crisis and environmental issues.Herein we report a novel g-C_(3)N_(4)/Ag In_(x)S_(y)S-scheme heterojunction photocatalyst for water splitting into stoichiometric H_(2)and H_(2)O_(2)under visible light.The catalyst was prepared by depositing 3D bimetallic sulfide(Ag In_(x)S_(y))nanotubes onto 2D g-C_(3)N_(4)nanosheets.Owing to the special 3D-on-2D configuration,the photogenerated carriers could be rapidly transferred and effectively separated through the abundant interfacial heterostructures to avoid recombination,and therefore excellent performance for visible light-driven water splitting could be obtained,with a 24-h H_(2)evolution rate up to 237μmol g^(-1)h^(-1).Furthermore,suitable band alignment enables simultaneous H_(2)and H_(2)O_(2)production in a 1:1 stoichiometric ratio.H_(2)and H_(2)O_(2)were evolved on the conduction band of g-C_(3)N_(4)and on the valance band of Ag In_(x)S_(y),respectively.The novel 3D-on-2D configuration for heterojunction construction proposed in this work provided alternative research ideas toward photocatalytic reaction.展开更多
Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-sc...Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-scheme photocatalysts were synthesized using electrospinning and calcination methods.The as-prepared SCN/TiO2 composites showed superior photocatalytic performance than pure TiO2 and SCN in the photocatalytic degradation of Congo Red(CR)aqueous solution.The significant enhancement in photocatalytic activity benefited not only from the 1D well-distributed nanostructure,but also from the S-scheme heterojunction.Furthermore,the XPS analyses and DFT calculations demonstrated that electrons were transferred from SCN to TiO2 across the interface of the SCN/TiO2 composites.The built-in electric field,band edge bending,and Coulomb interaction synergistically facilitated the recombination of relatively useless electrons and holes in hybrid when the interface was irradiated by simulated solar light.Therefore,the remaining electrons and holes with higher reducibility and oxidizability endowed the composite with supreme redox ability.These results were adequately verified by radical trapping experiments,ESR tests,and in situ XPS analyses,suggesting that the electron immigration in the photocatalyst followed the S-scheme heterojunction mechanism.This work can enrich our knowledge of the design and fabrication of novel S-scheme heterojunction photocatalysts and provide a promising strategy for solving environmental pollution in the future.展开更多
Converting sustainable solar energy into hydrogen energy over semiconductor-based photocatalytic materials provides an alternative to fossil fuel consumption.However,efficient photocatalytic splitting of water to real...Converting sustainable solar energy into hydrogen energy over semiconductor-based photocatalytic materials provides an alternative to fossil fuel consumption.However,efficient photocatalytic splitting of water to realize carbon-free hydrogen production remains a challenge.Heterojunction photocatalysts with well-defined dimensionality and perfectly matched interfaces are promising for achieving highly efficient solar-to-hydrogen conversion.Herein,we report the fabrication of a novel type of protonated graphitic carbon nitride(PCN)/Ti3C2 MXene heterojunctions with strong interfacial interactions.As expected,the two-dimensional(2D)PCN/2D Ti3C2 MXene interface heterojunction achieves a highly improved hydrogen evolution rate(2181μmol∙g‒1)in comparison with bulk g-C3N4(393μmol∙g‒1)and protonated g-C3N4(816μmol∙g‒1).The charge-regulated surfaces of PCN and the accelerated charge transport at the face-to-face 2D/2D Schottky heterojunction interface are the major contributors to the excellent hydrogen evolution performance of the composite photocatalyst.展开更多
A series of Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigate...A series of Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigated comprehensively in terms of crystal structure, morphology, composition, specific surface area, photoelectrochemical properties, photodegradation performance, etc. Compared with binary TiO2/g-C3N4 and single-component photocatalysts, ternary heterojunction photocatalysts show the best photodegradation performance for RhB under stimulated sunlight. This can be attributed to the enlarged specific surface area (111.41 m2/g), the formation of Z-scheme heterojunction, and the high separation migration efficiency of photoexcited charge carriers. A potential Z-scheme mechanism for ternary heterojunction photocatalysts is proposed to elucidate the remarkably ameliorated photocatalytic performance based on active species trapping experiments, PL detection test of hydroxyl radicals, and photoelectrochemical properties.展开更多
Ag nanoparticles (NPs) were deposited on the surface of g-C3N4 (CN) by an in situ calcination method. NiS was successfully loaded onto the composites by a hydrothermal method. The results showed that the 10 wt%-NiS/1....Ag nanoparticles (NPs) were deposited on the surface of g-C3N4 (CN) by an in situ calcination method. NiS was successfully loaded onto the composites by a hydrothermal method. The results showed that the 10 wt%-NiS/1.0 wt%-Ag/CN composite exhibits excellent photocatalytic H2 generation performance under solar-light irradiation. An H2 production rate of 9.728 mmol·g^-1·h^-1 was achieved, which is 10.82-, 3.45-, and 2.77-times higher than those of pure g-C3N4, 10 wt%-NiS/CN, and 1.0 wt%-Ag/CN composites, respectively. This enhanced photocatalytic H2 generation can be ascribed to the co-decoration of Ag and NiS on the surface of g-C3N4, which efficiently improves light harvesting capacity, photogenerated charge carrier separation, and photocatalytic H2 production kinetics. Thus, this study demonstrates an effective strategy for constructing excellent g-C3N4-related composite photocatalysts for H2 production by using different co-catalysts.展开更多
The unique heterojunction photocatalyst of graphite carbon nitride (g-C_(3)N_(4)) modified ultrafine TiO_(2) (g-C_(3)N_(4)/TiO_(2)) was successfully fabricated by electrochemical etching and co-annealing method. Howev...The unique heterojunction photocatalyst of graphite carbon nitride (g-C_(3)N_(4)) modified ultrafine TiO_(2) (g-C_(3)N_(4)/TiO_(2)) was successfully fabricated by electrochemical etching and co-annealing method. However, the effects of various environmental factors on the degradation of TC by g-C_(3)N_(4)/TiO_(2) and the internal reaction mechanism are still unclear. In this study, the effects of initial pH, anions, and cations on the photocatalytic degradation of tetracycline hydrochloride (TC) by g-C_(3)N_(4)/TiO_(2) were systematically explored, and the scavenging experiment and intermediate detection were conducted to better reveal the mechanism on photocatalytic degradation of TC. The results showed that the removal efficiency of photocatalytic degradation of TC by g-C_(3)N_(4)/TiO_(2) could reach 99.04% under Xenon lamp irradiation within 120 min. The unique g-C_(3)N_(4)/TiO_(2) heterojunction photocatalyst showed excellent photocatalytic performance for the degradation of TC at pH 3~7, and possesses outstanding anti-interference ability to NO_(3)^(-), Cl^(-), Na^(+), Ca^(2+) and Mg^(2+) ions in natural waters during the photocatalytic degradation TC process. Superoxide radicals (O_(2)^(·-)) and hydroxyl radicals (^(·)OH) were proved as the main reactive species for TC degradation, and the possible mechanism of the unique photocatalytic system for g-C_(3)N_(4)/TiO_(2) was also proposed. The above results can provide a reliable basis and theoretical guidance for the design and application of visible photocatalyst with high activity to degrade the actual wastewater containing TC.展开更多
The surface plasmonic resonance(SPR)effect of Bi can effectively improve the light absorption abilities and photogenerated charge carrier separation rate.In this study,a novel ternary heterojunction of g-C3N4/Bi2MoO6/...The surface plasmonic resonance(SPR)effect of Bi can effectively improve the light absorption abilities and photogenerated charge carrier separation rate.In this study,a novel ternary heterojunction of g-C3N4/Bi2MoO6/Bi(CN/BMO/Bi)hollow microsphere was successfully fabricated through solvothermal and in situ reduction methods.The results revealed that the optimal ternary 0.4 CN/BMO/9 Bi photocatalyst exhibited the highest photocatalytic efficiency toward rhodamine B(RhB)degradation with nine times that of pure BMO.The DRS and valence band of the X-ray photoelectron spectroscopy spectrum demonstrate that the band structure of 0.4 CN/BMO/9 Bi is a z-scheme structure.Quenching experiments also provided solid evidence that the·O^2-(at-0.33 eV)is the main species during dye degradation,and the conduction band of g-C3N4 is only the reaction site,demonstrating that the transfer of photogenerated charge carriers of g-C3N4/Bi2 MoO 6/Bi is through an indirect z-scheme structure.Thus,the enhanced photocatalytic performance was mainly ascribed to the synergetic effect of heterojunction structures between g-C3N4 and Bi2MoO6 and the SPR effect of Bi doping,resulting in better optical absorption ability and a lower combination rate of photogenerated charge carriers.The findings in this work provide insight into the synergism of heterostructures and the SPR absorption ability in wastewater treatment.展开更多
In this study, CdS/g-C3N4 （CSCN） heterojunctions were in situ fabricated with a large amount of CdS nanoparticles anchored on g-C3N4 nanosheets, A wet chemical method was developed for the first time to determine th...In this study, CdS/g-C3N4 （CSCN） heterojunctions were in situ fabricated with a large amount of CdS nanoparticles anchored on g-C3N4 nanosheets, A wet chemical method was developed for the first time to determine the actual content of CdS in CSCN composites. X-ray diffraction （XRD）, Fourier transform infrared spectra （FFIR）, high-resolution transmission electron microscopy （HRTEM） and UV-vis diffuse reflectance spectra （DRS） were employed to characterize the composition, structure and optical prop- erty of CSCN composites. Based on the is0electric point （liP） analysis of g-C3N4, a conclusion was obtained on the combination mechanism between CdS nanoparticles and g-C3N4 nanosheets. The photocatalytic activity of CSCN composites was much better than those of individual CdS and g-C3N4 for the degrada- tion of azo dye Methyl Orange （MO） by 40 min adsorption in the dark followed by 15 min photocatalysis under visible light irradiation. After 5 cycles, CSCN composites still maintained high reactive activity with the MO degradation efficiency of 93.8%, exhibiting good photocatalytic stability. The Cd2~ concentration dissolved in the supernatant detected by atomic absorption spectroscopy （AAS） of CSCN composites was lower than that of pure CdS, implying that the photocorrosion of CdS could be suppressed via the combination with g-C3N4. Photoluminescence emission spectra （PL） results clearly revealed that the recombination of photogenerated electron-hole pairs in CSCN composites was effectively inhibited due to the formation of heterojunctions. Based on the band alignments of g-C3N4 and CdS, the possible photocatalvtic mechnism was discussed.展开更多
A simple calcination method was employed to prepare a Z-scheme N-doped K4Nb6O17/g-C3N4(KCN)heterojunction photocatalyst,in which the electronic structure of K4Nb6O17 was regulated by N-doping,and g-C3N4 was formed bot...A simple calcination method was employed to prepare a Z-scheme N-doped K4Nb6O17/g-C3N4(KCN)heterojunction photocatalyst,in which the electronic structure of K4Nb6O17 was regulated by N-doping,and g-C3N4 was formed both on the surface and within the interlayer spaces of K4Nb6O17.The KCN composite showed profoundly improved photocatalytic activity for both H2 generation and RhB degradation compared to its counterparts.This improved performance was attributed to the synergistic effects of N-doping,which broadened its light harvesting ability,and heterojunction formation,which increased the charge separation rate.The relatively low BET specific surface area of the KCN composite had little effect on its photocatalytic activity.Based on ESR spectroscopy studies,•O2^−,•OH,and h^+are the main active species in the photocatalytic degradation of RhB.Thus,it is reasonable to propose a Z-scheme photocatalytic mechanism over the KCN composite,which exhibits the dual advantages of efficient charge separation and high redox ability.Our work provides a simple approach for constructing large-scale Z-scheme heterojunction photocatalysts with high photocatalytic performance.展开更多
The CdS/spherical g-C3N4 n-n heterojunction photocatalyst was fabricated via a solvothermal method.The tetracycline was used to characterize the photocatalytic properties of the as-developed hybrids.The photocatalytic...The CdS/spherical g-C3N4 n-n heterojunction photocatalyst was fabricated via a solvothermal method.The tetracycline was used to characterize the photocatalytic properties of the as-developed hybrids.The photocatalytic degradation mechanism of the as-developed heterojunction photocatalyst was also analyzed.Research results show that CdS nanoparticles are well dispersed in the surface layer of spherical g-C3N4.Moreover,the mass ratio of CdS to spherical g-C3N4 will influence the photocatalytic activity of the asdeveloped composites,which shows the trend of first increasing and then decreasing as it increased.When the mass ratio is 7:1,in 25 min,the as-developed heterojunction shows 93.2%of the maximum photocatalytic efficiency and still exhibits 83.6%after 5 times cycle testing.Moreover,the as-developed hybrids can accelerate the electron transport and improve the separation efficiency of photo-generated carriers compared with pure samples.In addition,the holes and superoxide radicals are dominating active species during the photocatalytic degradation process.展开更多
Novel WO3/g-C3N4/Ni（OH）x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition.Their photocatalytic performance was investigated using TEOA as ...Novel WO3/g-C3N4/Ni（OH）x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition.Their photocatalytic performance was investigated using TEOA as a hole scavenger under visible light irradiation.The loading of WO3 and Ni（OH）x cocatalysts boosted the photocatalytic H2 evolution efficiency of g-C3N4.WO3/g-C3N4/Ni（OH）x with 20 wt%defective WO3 and 4.8 wt%Ni（OH）x showed the highest hydrogen production rate of 576 μmol/（g·h）,which was 5.7,10.8 and 230 times higher than those of g-C3N4/4.8 wt%Ni（OH）x,20 wt%WO3/C3N4 and g-C3N4 photocatalysts,respectively.The remarkably enhanced H2 evolution performance was ascribed to the combination effects of the Z-scheme heterojunction（WO3/g-C3N4） and loaded cocatalysts（Ni（OH）x）,which effectively inhibited the recombination of the photoexcited electron-hole pairs of g-C3N4 and improved both H2 evolution and TEOA oxidation kinetics.The electron spin resonance spectra of ·O2^- and ·OH radicals provided evidence for the Z-scheme charge separation mechanism.The loading of easily available Ni（OH）x cocatalysts on the Z-scheme WO3/g-C3N4 nanocomposites provided insights into constructing a robust multiple-heterojunction material for photocatalytic applications.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52362012,42077162,51978323)Natural Science Foundation of Jiangxi Province(No.2022ACB203014)+4 种基金Major Discipline Academic and Technical Leaders Training Program of Jiangxi Province(Nos.20213BCJ22018,20232BCJ22048)Natural Science Project of the Educational Department in Jiangxi Province(No.GJJ2201121)Natural Science Foundation of Nanchang Hangkong University(No.EA202202256)Educational Reform Project of Jiangxi Province(No.JXYJG-2022-135)Nanchang Hangkong University Educational Reform Project(Nos.sz2214,sz2213,JY22017,KCPY1806)。
文摘Photocatalytic H_(2)production from water splitting is a promising candidate for solving the increasing energy crisis and environmental issues.Herein we report a novel g-C_(3)N_(4)/Ag In_(x)S_(y)S-scheme heterojunction photocatalyst for water splitting into stoichiometric H_(2)and H_(2)O_(2)under visible light.The catalyst was prepared by depositing 3D bimetallic sulfide(Ag In_(x)S_(y))nanotubes onto 2D g-C_(3)N_(4)nanosheets.Owing to the special 3D-on-2D configuration,the photogenerated carriers could be rapidly transferred and effectively separated through the abundant interfacial heterostructures to avoid recombination,and therefore excellent performance for visible light-driven water splitting could be obtained,with a 24-h H_(2)evolution rate up to 237μmol g^(-1)h^(-1).Furthermore,suitable band alignment enables simultaneous H_(2)and H_(2)O_(2)production in a 1:1 stoichiometric ratio.H_(2)and H_(2)O_(2)were evolved on the conduction band of g-C_(3)N_(4)and on the valance band of Ag In_(x)S_(y),respectively.The novel 3D-on-2D configuration for heterojunction construction proposed in this work provided alternative research ideas toward photocatalytic reaction.
文摘Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-scheme photocatalysts were synthesized using electrospinning and calcination methods.The as-prepared SCN/TiO2 composites showed superior photocatalytic performance than pure TiO2 and SCN in the photocatalytic degradation of Congo Red(CR)aqueous solution.The significant enhancement in photocatalytic activity benefited not only from the 1D well-distributed nanostructure,but also from the S-scheme heterojunction.Furthermore,the XPS analyses and DFT calculations demonstrated that electrons were transferred from SCN to TiO2 across the interface of the SCN/TiO2 composites.The built-in electric field,band edge bending,and Coulomb interaction synergistically facilitated the recombination of relatively useless electrons and holes in hybrid when the interface was irradiated by simulated solar light.Therefore,the remaining electrons and holes with higher reducibility and oxidizability endowed the composite with supreme redox ability.These results were adequately verified by radical trapping experiments,ESR tests,and in situ XPS analyses,suggesting that the electron immigration in the photocatalyst followed the S-scheme heterojunction mechanism.This work can enrich our knowledge of the design and fabrication of novel S-scheme heterojunction photocatalysts and provide a promising strategy for solving environmental pollution in the future.
文摘Converting sustainable solar energy into hydrogen energy over semiconductor-based photocatalytic materials provides an alternative to fossil fuel consumption.However,efficient photocatalytic splitting of water to realize carbon-free hydrogen production remains a challenge.Heterojunction photocatalysts with well-defined dimensionality and perfectly matched interfaces are promising for achieving highly efficient solar-to-hydrogen conversion.Herein,we report the fabrication of a novel type of protonated graphitic carbon nitride(PCN)/Ti3C2 MXene heterojunctions with strong interfacial interactions.As expected,the two-dimensional(2D)PCN/2D Ti3C2 MXene interface heterojunction achieves a highly improved hydrogen evolution rate(2181μmol∙g‒1)in comparison with bulk g-C3N4(393μmol∙g‒1)and protonated g-C3N4(816μmol∙g‒1).The charge-regulated surfaces of PCN and the accelerated charge transport at the face-to-face 2D/2D Schottky heterojunction interface are the major contributors to the excellent hydrogen evolution performance of the composite photocatalyst.
基金supported by the Scientific Research Project from Hubei Provincial Department of Education(Q20181808)the Research and Innovation Initiatives of Wuhan Polytechnic University(2018J04,2018Y07)~~
文摘A series of Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigated comprehensively in terms of crystal structure, morphology, composition, specific surface area, photoelectrochemical properties, photodegradation performance, etc. Compared with binary TiO2/g-C3N4 and single-component photocatalysts, ternary heterojunction photocatalysts show the best photodegradation performance for RhB under stimulated sunlight. This can be attributed to the enlarged specific surface area (111.41 m2/g), the formation of Z-scheme heterojunction, and the high separation migration efficiency of photoexcited charge carriers. A potential Z-scheme mechanism for ternary heterojunction photocatalysts is proposed to elucidate the remarkably ameliorated photocatalytic performance based on active species trapping experiments, PL detection test of hydroxyl radicals, and photoelectrochemical properties.
基金supported by the National Natural Science Foundation of China(21676213,21476183,51372201)the China Postdoctoral Science Foundation(2016M600809)the Natural Science Basic Research Plan in Shaanxi Province of China(2017JM2026)~~
文摘Ag nanoparticles (NPs) were deposited on the surface of g-C3N4 (CN) by an in situ calcination method. NiS was successfully loaded onto the composites by a hydrothermal method. The results showed that the 10 wt%-NiS/1.0 wt%-Ag/CN composite exhibits excellent photocatalytic H2 generation performance under solar-light irradiation. An H2 production rate of 9.728 mmol·g^-1·h^-1 was achieved, which is 10.82-, 3.45-, and 2.77-times higher than those of pure g-C3N4, 10 wt%-NiS/CN, and 1.0 wt%-Ag/CN composites, respectively. This enhanced photocatalytic H2 generation can be ascribed to the co-decoration of Ag and NiS on the surface of g-C3N4, which efficiently improves light harvesting capacity, photogenerated charge carrier separation, and photocatalytic H2 production kinetics. Thus, this study demonstrates an effective strategy for constructing excellent g-C3N4-related composite photocatalysts for H2 production by using different co-catalysts.
基金financially supported by National Natural Science Foundation of China (Nos. 52070107, 51678323)Natural Science Foundation of Shandong Province (Nos. ZR2019MD012,ZR2017MEE026)+1 种基金Support Plan on Youth Innovation Science and Technology for Higher Education of Shandong Province (No.2019KJD014)Natural Science Foundation of Heilongjiang Province (No. B2015024)。
文摘The unique heterojunction photocatalyst of graphite carbon nitride (g-C_(3)N_(4)) modified ultrafine TiO_(2) (g-C_(3)N_(4)/TiO_(2)) was successfully fabricated by electrochemical etching and co-annealing method. However, the effects of various environmental factors on the degradation of TC by g-C_(3)N_(4)/TiO_(2) and the internal reaction mechanism are still unclear. In this study, the effects of initial pH, anions, and cations on the photocatalytic degradation of tetracycline hydrochloride (TC) by g-C_(3)N_(4)/TiO_(2) were systematically explored, and the scavenging experiment and intermediate detection were conducted to better reveal the mechanism on photocatalytic degradation of TC. The results showed that the removal efficiency of photocatalytic degradation of TC by g-C_(3)N_(4)/TiO_(2) could reach 99.04% under Xenon lamp irradiation within 120 min. The unique g-C_(3)N_(4)/TiO_(2) heterojunction photocatalyst showed excellent photocatalytic performance for the degradation of TC at pH 3~7, and possesses outstanding anti-interference ability to NO_(3)^(-), Cl^(-), Na^(+), Ca^(2+) and Mg^(2+) ions in natural waters during the photocatalytic degradation TC process. Superoxide radicals (O_(2)^(·-)) and hydroxyl radicals (^(·)OH) were proved as the main reactive species for TC degradation, and the possible mechanism of the unique photocatalytic system for g-C_(3)N_(4)/TiO_(2) was also proposed. The above results can provide a reliable basis and theoretical guidance for the design and application of visible photocatalyst with high activity to degrade the actual wastewater containing TC.
基金financially supported by the Science Foundation of China University of Petroleum,Beijing(2462017YJRC048,2462018BJC005)the National Natural Science Foundation of China(51802351)~~
文摘The surface plasmonic resonance(SPR)effect of Bi can effectively improve the light absorption abilities and photogenerated charge carrier separation rate.In this study,a novel ternary heterojunction of g-C3N4/Bi2MoO6/Bi(CN/BMO/Bi)hollow microsphere was successfully fabricated through solvothermal and in situ reduction methods.The results revealed that the optimal ternary 0.4 CN/BMO/9 Bi photocatalyst exhibited the highest photocatalytic efficiency toward rhodamine B(RhB)degradation with nine times that of pure BMO.The DRS and valence band of the X-ray photoelectron spectroscopy spectrum demonstrate that the band structure of 0.4 CN/BMO/9 Bi is a z-scheme structure.Quenching experiments also provided solid evidence that the·O^2-(at-0.33 eV)is the main species during dye degradation,and the conduction band of g-C3N4 is only the reaction site,demonstrating that the transfer of photogenerated charge carriers of g-C3N4/Bi2 MoO 6/Bi is through an indirect z-scheme structure.Thus,the enhanced photocatalytic performance was mainly ascribed to the synergetic effect of heterojunction structures between g-C3N4 and Bi2MoO6 and the SPR effect of Bi doping,resulting in better optical absorption ability and a lower combination rate of photogenerated charge carriers.The findings in this work provide insight into the synergism of heterostructures and the SPR absorption ability in wastewater treatment.
基金supported by the National Scientific Foundation of China(NSFC,Project no.21306119)the Provincial Natural Science Foundation of Sichuan(2013FZ0034 and 2013JY0150)the Outstanding Young Scientist Foundation of Sichuan University(2013SCU04A23)
基金financially supported by the National Natural Science Foundation of China(Nos.51404083 and 21273060)the Program for New Century Excellent Talents in Heilongjiang Provincial Universities(No.1253-NCET-010)the Natural Science Foundation of Heilongjiang Province,China(No.E2015065)
文摘In this study, CdS/g-C3N4 （CSCN） heterojunctions were in situ fabricated with a large amount of CdS nanoparticles anchored on g-C3N4 nanosheets, A wet chemical method was developed for the first time to determine the actual content of CdS in CSCN composites. X-ray diffraction （XRD）, Fourier transform infrared spectra （FFIR）, high-resolution transmission electron microscopy （HRTEM） and UV-vis diffuse reflectance spectra （DRS） were employed to characterize the composition, structure and optical prop- erty of CSCN composites. Based on the is0electric point （liP） analysis of g-C3N4, a conclusion was obtained on the combination mechanism between CdS nanoparticles and g-C3N4 nanosheets. The photocatalytic activity of CSCN composites was much better than those of individual CdS and g-C3N4 for the degrada- tion of azo dye Methyl Orange （MO） by 40 min adsorption in the dark followed by 15 min photocatalysis under visible light irradiation. After 5 cycles, CSCN composites still maintained high reactive activity with the MO degradation efficiency of 93.8%, exhibiting good photocatalytic stability. The Cd2~ concentration dissolved in the supernatant detected by atomic absorption spectroscopy （AAS） of CSCN composites was lower than that of pure CdS, implying that the photocorrosion of CdS could be suppressed via the combination with g-C3N4. Photoluminescence emission spectra （PL） results clearly revealed that the recombination of photogenerated electron-hole pairs in CSCN composites was effectively inhibited due to the formation of heterojunctions. Based on the band alignments of g-C3N4 and CdS, the possible photocatalvtic mechnism was discussed.
文摘A simple calcination method was employed to prepare a Z-scheme N-doped K4Nb6O17/g-C3N4(KCN)heterojunction photocatalyst,in which the electronic structure of K4Nb6O17 was regulated by N-doping,and g-C3N4 was formed both on the surface and within the interlayer spaces of K4Nb6O17.The KCN composite showed profoundly improved photocatalytic activity for both H2 generation and RhB degradation compared to its counterparts.This improved performance was attributed to the synergistic effects of N-doping,which broadened its light harvesting ability,and heterojunction formation,which increased the charge separation rate.The relatively low BET specific surface area of the KCN composite had little effect on its photocatalytic activity.Based on ESR spectroscopy studies,•O2^−,•OH,and h^+are the main active species in the photocatalytic degradation of RhB.Thus,it is reasonable to propose a Z-scheme photocatalytic mechanism over the KCN composite,which exhibits the dual advantages of efficient charge separation and high redox ability.Our work provides a simple approach for constructing large-scale Z-scheme heterojunction photocatalysts with high photocatalytic performance.
基金Funded by the Natural Science Foundation of Hebei Province,China(Nos.E2019210251 and B2019210331).
文摘The CdS/spherical g-C3N4 n-n heterojunction photocatalyst was fabricated via a solvothermal method.The tetracycline was used to characterize the photocatalytic properties of the as-developed hybrids.The photocatalytic degradation mechanism of the as-developed heterojunction photocatalyst was also analyzed.Research results show that CdS nanoparticles are well dispersed in the surface layer of spherical g-C3N4.Moreover,the mass ratio of CdS to spherical g-C3N4 will influence the photocatalytic activity of the asdeveloped composites,which shows the trend of first increasing and then decreasing as it increased.When the mass ratio is 7:1,in 25 min,the as-developed heterojunction shows 93.2%of the maximum photocatalytic efficiency and still exhibits 83.6%after 5 times cycle testing.Moreover,the as-developed hybrids can accelerate the electron transport and improve the separation efficiency of photo-generated carriers compared with pure samples.In addition,the holes and superoxide radicals are dominating active species during the photocatalytic degradation process.
基金supported by the National Natural Science Foundation of China (51672089)the Industry and Research Collaborative Innovation Major Projects of Guangzhou (201508020098)+1 种基金the State Key Laboratory of Advanced Technology for Material Synthesis and Processing (Wuhan University of Technology) (2015-KF-7)the Hunan Key Laboratory of Applied Environmental Photocatalysis (Changsha University) (CCSU-XT-04)~~
文摘Novel WO3/g-C3N4/Ni（OH）x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition.Their photocatalytic performance was investigated using TEOA as a hole scavenger under visible light irradiation.The loading of WO3 and Ni（OH）x cocatalysts boosted the photocatalytic H2 evolution efficiency of g-C3N4.WO3/g-C3N4/Ni（OH）x with 20 wt%defective WO3 and 4.8 wt%Ni（OH）x showed the highest hydrogen production rate of 576 μmol/（g·h）,which was 5.7,10.8 and 230 times higher than those of g-C3N4/4.8 wt%Ni（OH）x,20 wt%WO3/C3N4 and g-C3N4 photocatalysts,respectively.The remarkably enhanced H2 evolution performance was ascribed to the combination effects of the Z-scheme heterojunction（WO3/g-C3N4） and loaded cocatalysts（Ni（OH）x）,which effectively inhibited the recombination of the photoexcited electron-hole pairs of g-C3N4 and improved both H2 evolution and TEOA oxidation kinetics.The electron spin resonance spectra of ·O2^- and ·OH radicals provided evidence for the Z-scheme charge separation mechanism.The loading of easily available Ni（OH）x cocatalysts on the Z-scheme WO3/g-C3N4 nanocomposites provided insights into constructing a robust multiple-heterojunction material for photocatalytic applications.
