S-型异质结CeO_(2)/Zn_(x)Cd_(1-x)In_(2)S_(4)空心结构的构建及其可见光分解水制氢性能

Constructing a CeO_(2)/Zn_(x)Cd_(1−x)In_(2)S_(4) S-Scheme Hollow Heterostructure for Efficient Photocatalytic H2 Evolution

层状结构材料ZnIn_(2)S_(4)(ZIS)具有强的可见光吸收、合适的能带结构、高的化学稳定性和低毒性,是优良的光催化材料。然而,ZIS的低载流子分离效率造成其光催化产氢效率较低。为了解决这一难题,本文提出了一种整合固溶体形成和异质结构建的能带结构调控策略。通过在CeO_(2)空心球表面原位生长ZnxCd1-xIn_(2)S_(4)(ZCIS)纳米片,成功制备了具有分级中空结构的CeO_(2)/ZCIS复合光催化剂。制备的1:6-CeO_(2)/Zn_(0.9)Cd_(0.1)In_(2)S_(4)样品在可见光下表现出了4.09 mmol·g^(-1)·h^(-1)的最佳产氢速率,分别是ZIS、ZCIS和CeO_(2)/ZIS的6.8、3.0和2.2倍。其光催化活性的显著增强主要归功于CeO_(2)/ZCIS的能带结构改变产生S-型异质结电荷传输通道。同时,引入Cd阳离子使得ZIS的导带和价带同时上移,为水裂解提供强还原性光电子。相比于CeO_(2)/ZIS异质结,ZCIS和CeO_(2)之间存在更大的费米能级差,可促进更多的自由电子从ZCIS转移到CeO_(2),在CeO_(2)/ZCIS界面形成强内建电场,促进载流子有效分离,提高光催化产氢效率。本研究将为S-型异质结光催化材料设计和构筑提供一种有效策略。

With the exhaustion of fossil energy,the energy crisis is becoming increasingly serious,which greatly hinders the sustainable development of society.Therefore,the development of new energy technologies as a substitute for non-renewable and highly polluting fossil energy is extremely urgent.The environmental benefits and high energy density of hydrogen(H_(2))make it an ideal clean energy source.Photocatalytic water splitting,which was first demonstrated in the pioneering work on TiO_(2) photoelectrodes under UV-light irradiation,has been extensively researched and has been shown to be an effective method for addressing the global energy crisis.However,most of the photocatalysts used for H_(2) production still suffer from low solar energy utilization and fast photogenerated charge recombination,which seriously limit their practical applications in the field of solar-to-hydrogen energy conversion.Therefore,it is necessary yet greatly challenging to develop a visible-light-responsive photocatalyst with efficient photogenerated charge separation through reasonable modification strategy.Layered structured ZnIn_(2)S_(4)(ZIS)is a promising photocatalyst to split water for H_(2) evolution owing to its suitable electronic structure,strong light absorption,chemical stability,and low toxicity.However,its low charge separation efficiency renders its photocatalytic performance unsatisfactory.Herein,to overcome this issue,a band structure regulation strategy that integrates solid solution formation with heterostructure construction was proposed.By growing Zn_(x)Cd_(1−x)In_(2)S_(4)(ZCIS)nanosheets on the surface of CeO_(2) hollow spheres in situ,a novel hollow heterostructure CeO_(2)/ZCIS with efficient charge separation was constructed as photocatalyst for H_(2) generation.The introduction of the Cd cation in ZIS upshifts the conduction band(CB)and valence band(VB)of ZCIS,enhancing the built-in electrical field on the interface.Those electronic band changes induce the S-scheme structure in CeO_(2)/ZCIS,promoting charge separation for photocatalysis.Moreover,the upshift of the CB generates photoelectrons with high H2 generation ability.As a result,the optimal 1:6-CeO_(2)/Zn_(0.9)Cd_(0.1)In_(2)S_(4) heterostructure exhibits 4.09 mmol·g^(−1)·h^(−1) H_(2) generation during photocatalysis,which is 6.8-,3.0-,and 2.2-fold as those of ZIS,ZCIS,and CeO_(2)/ZIS,respectively.This work provides one efficient strategy to develop highly active S-scheme photocatalysts for hydrogen generation.