The Structure Adjustment Of Zn₂GeO₄-based Photocatalyst And Its Photocatalytic Activity For Hydrogen Evolution

With the rapid development of society and industrialization,environmental pollution and energy crisis have become two major problems of sustainable development in the world today.Therefore,it is urgent to seek efficient,clean and pollution-free renewable energy to solve the current problems.Photocatalytic hydrogenation evolution from water has attracted wide attention due to its unique properties such as deep reaction at room temperature and direct use of solar energy as the lignt source to drive the reaction.Recently,semiconductor materials with d10 electronic structure have become a research hotspot because of high electron mobility and excellent performance in photo-catalysis field.In this paper,we chose Zn2GeO4 as main base material,in order to enhanced photocatalytic activity for hydrogen evolution of the Zn2GeO4.Firstly,we control the concentration of ZnS by adjusting the concentration of MoS2 and using the middle layer to improve the photocatalytic activity of hydrogen evolution;Secondly,we synthesized 3D nano-rod bundle of Zn2GeO4 by hydrothermal method and optimize its performance by building new structures.The main researches are showed as follows:In the first chapter,we introduces the fundamental,the reaction process and requirement of semiconductor photocatalytic water splitting technology.Also,we systematically study the research background of photo-catalysts and Zn2GeO4 semiconductor?Finally we introduced the research content of this thesis?In the second chapter,Zn2GeO4/MoS2 composites were prepared through hydrothermal method,and the concentration control of ZnS was realized by adjusting the amount of MoS2.We investigate the influence of ZnS on photocatalytic activity:On the one hand,ZnS can form a heterojunction with Zn2GeO4 which promotes the separation and transfer of electron-hole pairs;On the other hand,the presence of ZnS makes a small amount of Zn2+ doped into MoS2,which regulates the electron energy level of MoS2 and provides more active sites,thus greatly improving the hydrogenation efficiency.This work provides a new insight to design and development free-noble metal catalyst photocatalytic reaction.In the third chapter,we used ethylenediamine and sodium citrate as structure directing agent,synthesized the 3D nano-rod bundle of Zn2Ge04 by hydrothermal method.We studied the mechanism of the nano-rod bundle and the reasons for the enhancement of hydrogenation:the unique pore structure of nano-rods,which promoted the reflection and refraction of light,and improved the efficiency of light utilization.The interaction between the interface and the pore structure of the nano-rods facilitates the separation and transmission of the carrier and reduces the recombination of electron-hole pairs,thus greatly improving the hydrogenation efficiency.This work provides a new strategy to improve the photocatalytic activity of Zn2GeO4,which proposes a new insight to design and development special structure semiconductor photo-catalyst.In the last chapter,we summarized the conclusions and innovative points of this dissertation,previewed the further studies finally.