The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor ...The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.展开更多
在强光照射下,CdS量子点易发生光腐蚀现象,通过金属掺杂和复合的方式可以提高CdS的光催化性能和光稳定性。采用水热法合成了Zn掺杂CdS/g-C_(3)N_(4)复合纳米材料(Zn-CdS/g-C_(3)N_(4))。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、...在强光照射下,CdS量子点易发生光腐蚀现象,通过金属掺杂和复合的方式可以提高CdS的光催化性能和光稳定性。采用水热法合成了Zn掺杂CdS/g-C_(3)N_(4)复合纳米材料(Zn-CdS/g-C_(3)N_(4))。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和傅里叶变换红外光谱(FT-IR)等手段对Zn-CdS/g-C_(3)N_(4)复合材料的形貌、结构和组成等进行了表征。结果表明,Zn-CdS纳米颗粒附着在g-C_(3)N_(4)表面上,从而形成Zn-CdS/g-C_(3)N_(4)复合材料,且复合后材料带隙减小,光生电子-空穴复合率降低。在500 W Xe灯照射下,研究了Zn-CdS/g-C_(3)N_(4)对罗丹明B(RhB)的光催化降解性能。在最优条件下,光照40 min后,所制备的Zn-CdS/g-C_(3)N_(4)对RhB的光催化降解效率达99%。此外,所合成的Zn-CdS/g-C_(3)N_(4)复合材料光稳定性较高、可再生性好。这归因于Zn和Cd的协同作用以及与g-C_(3)N_(4)的复合,促进了光生载流子的分离和转移。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
文摘The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.
文摘在强光照射下,CdS量子点易发生光腐蚀现象,通过金属掺杂和复合的方式可以提高CdS的光催化性能和光稳定性。采用水热法合成了Zn掺杂CdS/g-C_(3)N_(4)复合纳米材料(Zn-CdS/g-C_(3)N_(4))。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和傅里叶变换红外光谱(FT-IR)等手段对Zn-CdS/g-C_(3)N_(4)复合材料的形貌、结构和组成等进行了表征。结果表明,Zn-CdS纳米颗粒附着在g-C_(3)N_(4)表面上,从而形成Zn-CdS/g-C_(3)N_(4)复合材料,且复合后材料带隙减小,光生电子-空穴复合率降低。在500 W Xe灯照射下,研究了Zn-CdS/g-C_(3)N_(4)对罗丹明B(RhB)的光催化降解性能。在最优条件下,光照40 min后,所制备的Zn-CdS/g-C_(3)N_(4)对RhB的光催化降解效率达99%。此外,所合成的Zn-CdS/g-C_(3)N_(4)复合材料光稳定性较高、可再生性好。这归因于Zn和Cd的协同作用以及与g-C_(3)N_(4)的复合,促进了光生载流子的分离和转移。
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.
