Surface/Interface Design Of Co-catalyst In The Synthesis Of TiO₂ And CdS Based Hybrid Nanomaterials And The Related Photocatalytic Mechanism Study

Energy shortage and environmental pollution caused by the burning of fossil fuels all over the world are becoming more and more serious.In order to solve these problems,it is imperative to find a suitable clean energy to replace fossil fuels.One of the most promising new technologies is photocatalytic technology,which is green and environmentally friendly,and has mild reaction conditions.However,the rapid recombination of photogenerated electron-hole pairs in semiconductors makes the synthesis of highly efficient photocatalysts always severe challenges.The hybrid photocatalyst can be developed through the integration of different components for having a synergistic effect and the surface of the co-catalysts can be rationally designed for enhancing the photocatalytic performance.In this work,we established a new type of stacked nanostructure by designing defects on the surface of the co-catalysts,synthesised a photocatalyst with excellent performance,and studied its potential photocatalytic mechanism.The contents of the main research are as follows:1.Vacancy engineering is performed on AuCu cocatalysts,which is realized via the acid treatment of AuCu nanocubes to etch surface Cu atoms away,which not only tailor the electronic structure of the cocatalysts and improve the electron trapping ability,but also alter the reactive pathway and product distribution.It is found that the removal of Cu from the Au matrix accelerates the migration of electrons to the cocatalysts and facilitates the8-electron reduction of CO₂ to CH₄,while low-coordinated Cu atoms surrounding the vacancies serve as reactive sites for the CO₂-to-CH₄ conversion.This work offers a defect design approach to engineer the lattice of cocatalyst at atomic precision to achieve high-selectivity conversion of CO₂into fuels.2.CdS embedded at interfaces between graphene and MoS₂ for improved photocatalytic H₂ evolution.In this design,CdS is directly supported by graphene nanosheets and simultaneously covered with few-layered metallic MoS₂ nanoflakes.The highly conductive MoS₂ cocatalysts not only act as high-efficient electron acceptors from CdS owing to the large area of the intimate contact between them,but also offer abundant reaction sites for H₂production due to the high percentage of the 1T phase involved.Moreover,CdS is completely encapsulated by MoS₂ and graphene which protected it from photocorrosion,in which MoS₂ shells accept the photogenerated holes from the CdS core,preventing the oxidation of S^2-,while graphene channels deliver the excessive electrons from the CdS core to the MoS₂ outer layers for H₂ evolution,suppressing the charge recombination in the MoS₂shell and enabling the participation of more MoS₂ in the proton reduction reaction.This study highlights the advantages of stack-structured photocatalysts and the importance of rationally choosing the stacking order.