Doping engineering is an effective strategy for graphitic carbon nitride(g-C_(3)N_(4))to improve its photocat-alytic hydrogen evolution reaction(HER)performance.In this work,a novel nitrogen and sulfur co-doped g-C_(3...Doping engineering is an effective strategy for graphitic carbon nitride(g-C_(3)N_(4))to improve its photocat-alytic hydrogen evolution reaction(HER)performance.In this work,a novel nitrogen and sulfur co-doped g-C_(3)N_(4)(N,S-g-C_(3)N_(4))is elaborately designed on the basis of theoretical predictions of first-principle density functional theory(DFT).The calculated Gibbs free energy of adsorbed hydrogen(ΔGH∗)for N,S-g-C_(3)N_(4) at the N-doping active sites is extremely close to zero(0.01 eV).Inspired by the theoretical predictions,the N,S-g-C_(3)N_(4) is successfully fabricated through ammonia-rich pyrolysis synthesis strategy,in which ammonia is in-situ obtained by pyrolyzing melamine.Subsequent characterizations indicate that the N,S-g-C_(3)N_(4) possesses high specific surface area,outstanding light utilization,good hydrophilicity,and efficient carrier transfer efficiency.Consequently,the N,S-g-C_(3)N_(4) displays an extremely high H2 evolution rate of 8269.9μmol g−1 h−1,achieves an apparent quantum efficiency(AQE)of 3.24%,and also possesses outsatnding durability.Theoretical calculations further demonstrate that N and S dopants can not only introduce doping energy level to reduce the band gap,but also induce charge redistribution to facilitate hydrogen adsorption,thus promoting the photocatalytic HER process.Moreover,femtosecond transient absorption(fs-TA)spectroscopy further corroborates the efficient photogenerated carrier transport of N,S-g-C_(3)N_(4).This research highlights a promising and reliable strategy to achieve superior photocatalytic activity,and exhibits significant guidance for precise designing high-efficiency photocatalysts.展开更多
Although bimetallic phosphide cocatalysts have attracted considerable interest in photocatalysis research owing to their advantageous thermodynamic characteristics,superstable and efficient cocatalysts have rarely bee...Although bimetallic phosphide cocatalysts have attracted considerable interest in photocatalysis research owing to their advantageous thermodynamic characteristics,superstable and efficient cocatalysts have rarely been produced through the modulation of their structure and composition.In this study,a series of bimetallic nickel-iron phosphide(Ni_(x)Fe_(2-x)P,where 0<x<2)cocatalysts with controllable structures and overpotentials were designed by adjusting the atomic ratio of Ni/Fe onto nonmetallic elemental red phosphorus(RP)for the photocatalytic selective oxidation of benzyl alcohol(BA)coupled with hydrogen production.The catalysts exhibited an outstanding photocatalytic activity for benzaldehyde and a high H_(2)yield.The RP regulated by bimetallic phosphide cocatalysts(Ni_(x)Fe_(2-x)P)demonstrated higher photocatalytic oxidation-reduction activity than that regulated by monometallic phosphide cocatalysts(Ni_(2)P and Fe2P).In particular,the RP regulated by Ni_(1.25)Fe_(0.75)P exhibited the best photocatalytic performance.In addition,experimental and theoretical calculations further illustrated that Ni_(1.25)Fe_(0.75)P,with the optimized electronic structure,possessed good electrical conductivity and provided strong adsorption and abundant active sites,thereby accelerating electron migration and lowering the reaction energy barrier of RP.This finding offers valuable insights into the rational design of highly effective cocatalysts aimed at optimizing the photocatalytic activity of composite photocatalysts.展开更多
The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS...The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS QDs and hollow nanotube In_(2)O_(3)is successfully achieved using an electrostatic self-assembly method.Under visible light irradiation,all CdS-In_(2)O_(3)composites exhibit higher hydrogen evolution efficiency compared to pure CdS QDs.Notably,the photocatalytic H_(2)evolution rate of the optimal CdS-7%In_(2)O_(3)composite is determined to be 2258.59μmol g^(−1)h^(−1),approximately 12.3 times higher than that of pure CdS.The cyclic test indicates that the CdS-In_(2)O_(3)composite maintains considerable activity even after 5 cycles,indicating its excellent stability.In situ X-ray photoelectron spectroscopy and density functional theory calculations confirm that carrier migration in CdS-In_(2)O_(3)composites adheres to a typical S-scheme heterojunction mechanism.Additionally,a series of characterizations demonstrate that the formation of S-scheme heterojunctions between In_(2)O_(3)and CdS inhibits charge recombination and accelerates the separation and migration of photogenerated carriers in the CdS QDs,thus achieving enhanced photocatalytic performance.This work elucidates the pivotal role of S-scheme heterojunctions in photocatalytic H_(2)production and offers novel insights into the construction of effective composite photocatalysts.展开更多
The intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates(H_(ad))to form strong S-H_(ad) bonds,resu...The intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates(H_(ad))to form strong S-H_(ad) bonds,resulting in a low photocatalytic H_(2) evolution activity.Herein,a cobalt-induced asymmetric electronic distribution is justified as an effective strategy to optimize the electronic configuration of catalytic S sites in NiCoS cocatalysts for highly active photocatalytic H_(2) evolution.To this end,Co atoms are uniformly incorporated in NiS nanoparticles to fabricate homogeneous NiCoS cocatalyst on TiO_(2) surface by a facile photosynthesis strategy.It is revealed that the incorporated Co atoms break the electron distribution symmetry in NiS,thus essentially increasing the electron density of S atoms to form active electron-enriched S^(2+δ)–sites.The electron-enriched S^(2+δ)–sites could interact with Had via an increased antibonding orbital occupancy,which weakens S–Had bonds for efficient H_(ad) adsorption and desorption,endowing the NiCoS cocatalysts with a highly active H_(2) evolution process.Consequently,the optimized NiCoS/TiO_(2)(1:2)photocatalyst displays the highest H_(2) production performance,outperforming the NiS/TiO_(2) and CoS/TiO_(2) samples by factors of 2.1 and 2.5,respectively.This work provides novel insights on breaking electron distribution symmetry to optimize catalytic efficiency of active sites.展开更多
High performance composite photocatalyst is a hotspot in the photocatalysis researches.In this study,a cutting-edge CeO_(2)/rutile composite photocatalyst with tiny CeO_(2)concentration of 1.28 wt%was synthesized via ...High performance composite photocatalyst is a hotspot in the photocatalysis researches.In this study,a cutting-edge CeO_(2)/rutile composite photocatalyst with tiny CeO_(2)concentration of 1.28 wt%was synthesized via a simple photocatalytic method.This as-obtained CeO_(2)/rutile catalyst(CeO_(2)/TiO_(2)-1:1)exhibited an enhanced wastewater degradation and improved water splitting H_(2)evolution ability,with 95.83%removal ratio for methylene blue(MB),72.84%for tetracycline(TC)and 87.57μmol/g H_(2)evolution capacity.Light irradiation and 2-coordinated oxygen vacancies(OV_(2C))on rutile surface promoted the Ce^(3+)adsorption on the rutile(110)facet as DFT results shown.The CeO_(2)/rutile type-Ⅱ heterojunction was evidenced to promote the migration of e^(−)/h^(+)and generation of·OH/·O_(2)^(−)and H_(2),which rapidly boosted the whole photocatalytic performance.This as-prepared CeO_(2)/TiO_(2)photocatalyst can provide useful inspirations and new thoughts about the photosynthesis process,and offer a novel strategy for heterojunction photocatalysts preparation.展开更多
Hydrogen peroxide(H_(2)O_(2)),an environmentally friendly chemical with high value,is extensively used in industrial production and daily life.However,the traditional anthraquinone method for H_(2)O_(2) production is ...Hydrogen peroxide(H_(2)O_(2)),an environmentally friendly chemical with high value,is extensively used in industrial production and daily life.However,the traditional anthraquinone method for H_(2)O_(2) production is associated with a highly energy-consuming and heavily polluting process.Solor-driven photocatalytic evolution of H_(2)O_(2) is a promising,eco-friendly,and energy-efficient strategy that holds great potential to substitute the traditional approach.Here,a ternary photocatalyst,NiS/CdS/Halloysite nanotubes(NiS/CdS/HNTs)is designed and prepared with an earth-abundant clay mineral HNTs as the support and NiS as a co-catalyst.The pivotal roles of HNTs and NiS in the photocatalytic process are elucidated by experiments and theoretical calculations.HNTs serve as the carrier,which allows CdS to be uniformly dispersed onto its surface as small particles,increasing effective contact with H_(2)O and O_(2) for H_(2)O_(2) formation.Simultaneously,it resulted in the formation of a Schottky junction between NiS and CdS,which not only favors photogenerated charges separating efficiently but also provides a unidirectional path to transfer electrons.Consequently,the optimized NiS/CdS/HNTs composite demonstrates an H_(2)O_(2) evolution rate of 380.5μmol·g^(-1)·h^(-1) without adding any sacrificial agent or extra O_(2),nearly 5.0 times that of pure CdS.This work suggests a feasible idea for designing and developing highly active and low-cost solar energy catalytic composite materials.展开更多
Developing efficient and stable catalysts for the hydrogen evolution reaction(HER)is essential for advancing anion-exchange membrane water electrolyzer(AEMWE)technology.In this study,we present a facile microwave redu...Developing efficient and stable catalysts for the hydrogen evolution reaction(HER)is essential for advancing anion-exchange membrane water electrolyzer(AEMWE)technology.In this study,we present a facile microwave reduction and low-temperature phosphorization strategy to synthesize a highly efficient HER catalyst,comprising P,N-codoped carbon-supported RuP_(2)nanocluster(RuP_(2)@PNC).RuP_(2)@PNC demonstrates outstanding HER performance,achieving overpotentials of 18 and 44 mV at a current density of 10 mA cm^(-2)in alkaline and acidic media,respectively.Furthermore,an AEMWE device utilizing RuP_(2)@PNC as the cathode catalyst delivers a current density of 0.5 A cm^(-2)at a cell voltage of 1.84 V and exhibits remarkable stability over 150 h of operation.Experimental analyses and density functional theory(DFT)calculations reveal that the synergistic effects of P,N-codoped and the unique structure of RuP_(2)enhance electron transfer between Ru and the support,optimize the electronic structure,and regulate the d–band center of Ru.These features improve water adsorption,weaken the Ru–H binding strength,and facilitate efficient H_(2)desorption,collectively driving the superior HER activity of RuP_(2)@PNC.This work offers an effective design strategy for high-performance HER catalysts and provides valuable insights for accelerating the development of AEMWE technology.展开更多
NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the mic...NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the microstructures of the g-C3N4 photocatalysts.In this study,a facile and low-temperature（80 ℃） impregnation method was developed to prepare NiS2/g-C3N4 photocatalysts.First,the g-C3N4 powders were processed by the hydrothermal method in order to introduce oxygen-containing functional groups（such as-OH and-C0NH-） to the surface of g-C3N4.Then,the Ni^2＋ ions could be adsorbed near the g-C3N4 via strong electrostatic interaction between g-C3N4 and Ni^2＋ ions upon the addition of Ni（NO3）2 solution.Finally,NiS2 nanoparticles were formed on the surface of g-C3N4 upon the addition of TAA.It was found that the NiS2 nanoparticles were solidly and homogeneously grafted on the surface of g-C3N4,resulting in greatly improved photocatalytic H2production.When the amount of NiS2 was 3 wt%,the resultant NiS2/g-C3N4 photocatalyst showed the highest H2 evolution rate（116.343 μmol h^-1 g^-1）,which is significantly higher than that of the pure g-C3N4（3 μmol h^-1 g^-1）.Moreover,the results of a recycling test for the NiS2/g-C3N4（3 wt%）sample showed that this sample could maintain a stable and effective photocatalytic H2-evolution performance under visible-light irradiation.Based on the above results,a possible mechanism of the improved photocatalytic performance was proposed for the presented NiS2/g-C3N4 photocatalysts,in which the photogenerated electrons of g-C3N4 can be rapidly transferred to the NiS2 nanoparticles via the close and continuous contact between them;then,the photogenerated electrons rapidly react with H2O adsorbed on the surface of NiS2,which has a surficial metallic character and high catalytic activity,to produce H2.Considering the mild and facile synthesis method,the presented low-cost and highly efficient NiS2-modified g-C3N4 photocatalysts would have great potential for practical use in photocatalytic H2 production.展开更多
基金supported by the National Natural Science Foun-dation of China(No.62004143)the Key R&D Program of Hubei Province(No.2022BAA084)the Natural Science Foundation of Hubei Province(No.2021CFB133).
文摘Doping engineering is an effective strategy for graphitic carbon nitride(g-C_(3)N_(4))to improve its photocat-alytic hydrogen evolution reaction(HER)performance.In this work,a novel nitrogen and sulfur co-doped g-C_(3)N_(4)(N,S-g-C_(3)N_(4))is elaborately designed on the basis of theoretical predictions of first-principle density functional theory(DFT).The calculated Gibbs free energy of adsorbed hydrogen(ΔGH∗)for N,S-g-C_(3)N_(4) at the N-doping active sites is extremely close to zero(0.01 eV).Inspired by the theoretical predictions,the N,S-g-C_(3)N_(4) is successfully fabricated through ammonia-rich pyrolysis synthesis strategy,in which ammonia is in-situ obtained by pyrolyzing melamine.Subsequent characterizations indicate that the N,S-g-C_(3)N_(4) possesses high specific surface area,outstanding light utilization,good hydrophilicity,and efficient carrier transfer efficiency.Consequently,the N,S-g-C_(3)N_(4) displays an extremely high H2 evolution rate of 8269.9μmol g−1 h−1,achieves an apparent quantum efficiency(AQE)of 3.24%,and also possesses outsatnding durability.Theoretical calculations further demonstrate that N and S dopants can not only introduce doping energy level to reduce the band gap,but also induce charge redistribution to facilitate hydrogen adsorption,thus promoting the photocatalytic HER process.Moreover,femtosecond transient absorption(fs-TA)spectroscopy further corroborates the efficient photogenerated carrier transport of N,S-g-C_(3)N_(4).This research highlights a promising and reliable strategy to achieve superior photocatalytic activity,and exhibits significant guidance for precise designing high-efficiency photocatalysts.
文摘Although bimetallic phosphide cocatalysts have attracted considerable interest in photocatalysis research owing to their advantageous thermodynamic characteristics,superstable and efficient cocatalysts have rarely been produced through the modulation of their structure and composition.In this study,a series of bimetallic nickel-iron phosphide(Ni_(x)Fe_(2-x)P,where 0<x<2)cocatalysts with controllable structures and overpotentials were designed by adjusting the atomic ratio of Ni/Fe onto nonmetallic elemental red phosphorus(RP)for the photocatalytic selective oxidation of benzyl alcohol(BA)coupled with hydrogen production.The catalysts exhibited an outstanding photocatalytic activity for benzaldehyde and a high H_(2)yield.The RP regulated by bimetallic phosphide cocatalysts(Ni_(x)Fe_(2-x)P)demonstrated higher photocatalytic oxidation-reduction activity than that regulated by monometallic phosphide cocatalysts(Ni_(2)P and Fe2P).In particular,the RP regulated by Ni_(1.25)Fe_(0.75)P exhibited the best photocatalytic performance.In addition,experimental and theoretical calculations further illustrated that Ni_(1.25)Fe_(0.75)P,with the optimized electronic structure,possessed good electrical conductivity and provided strong adsorption and abundant active sites,thereby accelerating electron migration and lowering the reaction energy barrier of RP.This finding offers valuable insights into the rational design of highly effective cocatalysts aimed at optimizing the photocatalytic activity of composite photocatalysts.
文摘The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS QDs and hollow nanotube In_(2)O_(3)is successfully achieved using an electrostatic self-assembly method.Under visible light irradiation,all CdS-In_(2)O_(3)composites exhibit higher hydrogen evolution efficiency compared to pure CdS QDs.Notably,the photocatalytic H_(2)evolution rate of the optimal CdS-7%In_(2)O_(3)composite is determined to be 2258.59μmol g^(−1)h^(−1),approximately 12.3 times higher than that of pure CdS.The cyclic test indicates that the CdS-In_(2)O_(3)composite maintains considerable activity even after 5 cycles,indicating its excellent stability.In situ X-ray photoelectron spectroscopy and density functional theory calculations confirm that carrier migration in CdS-In_(2)O_(3)composites adheres to a typical S-scheme heterojunction mechanism.Additionally,a series of characterizations demonstrate that the formation of S-scheme heterojunctions between In_(2)O_(3)and CdS inhibits charge recombination and accelerates the separation and migration of photogenerated carriers in the CdS QDs,thus achieving enhanced photocatalytic performance.This work elucidates the pivotal role of S-scheme heterojunctions in photocatalytic H_(2)production and offers novel insights into the construction of effective composite photocatalysts.
文摘The intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates(H_(ad))to form strong S-H_(ad) bonds,resulting in a low photocatalytic H_(2) evolution activity.Herein,a cobalt-induced asymmetric electronic distribution is justified as an effective strategy to optimize the electronic configuration of catalytic S sites in NiCoS cocatalysts for highly active photocatalytic H_(2) evolution.To this end,Co atoms are uniformly incorporated in NiS nanoparticles to fabricate homogeneous NiCoS cocatalyst on TiO_(2) surface by a facile photosynthesis strategy.It is revealed that the incorporated Co atoms break the electron distribution symmetry in NiS,thus essentially increasing the electron density of S atoms to form active electron-enriched S^(2+δ)–sites.The electron-enriched S^(2+δ)–sites could interact with Had via an increased antibonding orbital occupancy,which weakens S–Had bonds for efficient H_(ad) adsorption and desorption,endowing the NiCoS cocatalysts with a highly active H_(2) evolution process.Consequently,the optimized NiCoS/TiO_(2)(1:2)photocatalyst displays the highest H_(2) production performance,outperforming the NiS/TiO_(2) and CoS/TiO_(2) samples by factors of 2.1 and 2.5,respectively.This work provides novel insights on breaking electron distribution symmetry to optimize catalytic efficiency of active sites.
基金Project([2023]04)supported by the Science and Technology Innovation Team of Guizhou University,ChinaProject([2019]30)supported by the Cultivation Project of Guizhou University,ChinaProject(2022Z072)supported by the Ningbo 2025 Science and Technology Innovation Major Project Computing Support of the State Key Laboratory of Public Big Data,Guizhou University,China。
文摘High performance composite photocatalyst is a hotspot in the photocatalysis researches.In this study,a cutting-edge CeO_(2)/rutile composite photocatalyst with tiny CeO_(2)concentration of 1.28 wt%was synthesized via a simple photocatalytic method.This as-obtained CeO_(2)/rutile catalyst(CeO_(2)/TiO_(2)-1:1)exhibited an enhanced wastewater degradation and improved water splitting H_(2)evolution ability,with 95.83%removal ratio for methylene blue(MB),72.84%for tetracycline(TC)and 87.57μmol/g H_(2)evolution capacity.Light irradiation and 2-coordinated oxygen vacancies(OV_(2C))on rutile surface promoted the Ce^(3+)adsorption on the rutile(110)facet as DFT results shown.The CeO_(2)/rutile type-Ⅱ heterojunction was evidenced to promote the migration of e^(−)/h^(+)and generation of·OH/·O_(2)^(−)and H_(2),which rapidly boosted the whole photocatalytic performance.This as-prepared CeO_(2)/TiO_(2)photocatalyst can provide useful inspirations and new thoughts about the photosynthesis process,and offer a novel strategy for heterojunction photocatalysts preparation.
文摘Hydrogen peroxide(H_(2)O_(2)),an environmentally friendly chemical with high value,is extensively used in industrial production and daily life.However,the traditional anthraquinone method for H_(2)O_(2) production is associated with a highly energy-consuming and heavily polluting process.Solor-driven photocatalytic evolution of H_(2)O_(2) is a promising,eco-friendly,and energy-efficient strategy that holds great potential to substitute the traditional approach.Here,a ternary photocatalyst,NiS/CdS/Halloysite nanotubes(NiS/CdS/HNTs)is designed and prepared with an earth-abundant clay mineral HNTs as the support and NiS as a co-catalyst.The pivotal roles of HNTs and NiS in the photocatalytic process are elucidated by experiments and theoretical calculations.HNTs serve as the carrier,which allows CdS to be uniformly dispersed onto its surface as small particles,increasing effective contact with H_(2)O and O_(2) for H_(2)O_(2) formation.Simultaneously,it resulted in the formation of a Schottky junction between NiS and CdS,which not only favors photogenerated charges separating efficiently but also provides a unidirectional path to transfer electrons.Consequently,the optimized NiS/CdS/HNTs composite demonstrates an H_(2)O_(2) evolution rate of 380.5μmol·g^(-1)·h^(-1) without adding any sacrificial agent or extra O_(2),nearly 5.0 times that of pure CdS.This work suggests a feasible idea for designing and developing highly active and low-cost solar energy catalytic composite materials.
基金supported by the National Natural Science Foundation of China(Nos.52371222 and 52271211)the Natural Science Foundation of Hunan Province in China(Nos.2025JJ60350,2024JJ4022,and 2023JJ30277)+1 种基金the Key Research and Development Program of Hunan Province(No.2023GK2035)HORIZON–Marie Sk?odowska–Curie Actions–2021–PF(No.101065098),European Union
文摘Developing efficient and stable catalysts for the hydrogen evolution reaction(HER)is essential for advancing anion-exchange membrane water electrolyzer(AEMWE)technology.In this study,we present a facile microwave reduction and low-temperature phosphorization strategy to synthesize a highly efficient HER catalyst,comprising P,N-codoped carbon-supported RuP_(2)nanocluster(RuP_(2)@PNC).RuP_(2)@PNC demonstrates outstanding HER performance,achieving overpotentials of 18 and 44 mV at a current density of 10 mA cm^(-2)in alkaline and acidic media,respectively.Furthermore,an AEMWE device utilizing RuP_(2)@PNC as the cathode catalyst delivers a current density of 0.5 A cm^(-2)at a cell voltage of 1.84 V and exhibits remarkable stability over 150 h of operation.Experimental analyses and density functional theory(DFT)calculations reveal that the synergistic effects of P,N-codoped and the unique structure of RuP_(2)enhance electron transfer between Ru and the support,optimize the electronic structure,and regulate the d–band center of Ru.These features improve water adsorption,weaken the Ru–H binding strength,and facilitate efficient H_(2)desorption,collectively driving the superior HER activity of RuP_(2)@PNC.This work offers an effective design strategy for high-performance HER catalysts and provides valuable insights for accelerating the development of AEMWE technology.
基金supported by the National Natural Science Foundation of China (21277107, 21477094, 51672203, 51472192)the Program for New Century Excellent Talents in University (NCET-13-0944)the Fundamental Research Funds for the Central Universities (WUT 2015IB002)~~
文摘NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the microstructures of the g-C3N4 photocatalysts.In this study,a facile and low-temperature（80 ℃） impregnation method was developed to prepare NiS2/g-C3N4 photocatalysts.First,the g-C3N4 powders were processed by the hydrothermal method in order to introduce oxygen-containing functional groups（such as-OH and-C0NH-） to the surface of g-C3N4.Then,the Ni^2＋ ions could be adsorbed near the g-C3N4 via strong electrostatic interaction between g-C3N4 and Ni^2＋ ions upon the addition of Ni（NO3）2 solution.Finally,NiS2 nanoparticles were formed on the surface of g-C3N4 upon the addition of TAA.It was found that the NiS2 nanoparticles were solidly and homogeneously grafted on the surface of g-C3N4,resulting in greatly improved photocatalytic H2production.When the amount of NiS2 was 3 wt%,the resultant NiS2/g-C3N4 photocatalyst showed the highest H2 evolution rate（116.343 μmol h^-1 g^-1）,which is significantly higher than that of the pure g-C3N4（3 μmol h^-1 g^-1）.Moreover,the results of a recycling test for the NiS2/g-C3N4（3 wt%）sample showed that this sample could maintain a stable and effective photocatalytic H2-evolution performance under visible-light irradiation.Based on the above results,a possible mechanism of the improved photocatalytic performance was proposed for the presented NiS2/g-C3N4 photocatalysts,in which the photogenerated electrons of g-C3N4 can be rapidly transferred to the NiS2 nanoparticles via the close and continuous contact between them;then,the photogenerated electrons rapidly react with H2O adsorbed on the surface of NiS2,which has a surficial metallic character and high catalytic activity,to produce H2.Considering the mild and facile synthesis method,the presented low-cost and highly efficient NiS2-modified g-C3N4 photocatalysts would have great potential for practical use in photocatalytic H2 production.
