Study On Visible Light Degradation Bio-dye And Photoelectrochemical Performance Of Cu 2 O And ZnO-based Micro/nano Structures

Effective development and utilization of solar energy resources by developing photocatalysis and photoelectrochemical technology is an effective way to solve the environmental pollution and energy shortage problems.In recent years,desiging and developing semiconductor materials with high photocatalytic activity are very important due to their wide applications in photocatalytic degradation of organic dyes,photoelectrochemical?PEC?water splitting.However,due to the high recombination rate of the photo-generated electron-hole pairs of the semiconductor photocatalyst,the applications of the semiconductor material in photocatalytic environmental remediation and PEC water splitting to generated hegrogen are limited.Therefore,the development of highly efficient photocatalytic materials and photoelectrode materials to solve the energy and pollution problems has important practical significance.In this thesis,heterogenous metal-semiconductor composites were fabricated by loading precious metal Au on the surface of metal oxide semiconductor,including Au@Cu₂O Schottky contact heterostructure and Au@ZnO nanorod arrays?NRAS?heterostructure.The Schottky barrier formed at the interfance of metal Au and semiconductor and surface plasmon resonance?SPR?of the metal Au nanoparticles facilitate the separation of the photogenerated electron-hole pairs,thereby improving the efficiency of the semiconductor photocatalyst to degrade organic contaminants and photocatalytic water splitting.This thesis mainly focuses on the following works.1.Using copper acetate and sodium hydroxide as raw materials,the Cu₂O micro/nanostructures with cubic morphology were synthesized by a simple hydrothermal method,in which the concentration of reducing agent,dropping speed and reaction time were controlled carefully.Then,the Au nanoparticles were deposited on the surface of Cu₂O microcubes to Au@Cu₂O Schottky heterostructures by reducing the chloroauric acid solution.The instantaneous photocurrent-time characteristic curves were measured by using standard three-electrode system.Cu₂O microcubes and Au@Cu₂O Schottky heterostructures as the working electrode,respectively.The photocurrent density of the as-prepared Au@Cu₂O heterostructure electrode reaches up to 30?A cm-2,which is 3 times higher than that?10 ?A cm-2?of pure Cu₂O microcube electrode at 1.23 V vs RHE.2.The methyl orange?MO?solution was used as the model pollutant.The prepared Cu₂O microcubic structures and Au@Cu₂O Schottky heterostructures were used as the photocatalyst to study the photocatalytic degradation of MO under visible light,respectively.By comparison,the degradation rate of MO by Au@Cu₂O Schottky heterostructures was 1.2 times higher than that of pure Cu₂O microcubic structures.The enhanced photocatalytic activity of the as-constructed Au@Cu₂O Schottky contact heterostructures is attributed to the synergistic effect of inner electronic field and Schokkty barrier.The transfer process of the photoexcited electrons and holes,and the enhancement mechanism of photocatalytic performance of the as-fabricated Au@Cu₂O heterostructures are discussed in detail.3.ZnO nanorod arrays were fabricated on the surface of FTO by ZnO seed-assisted electrochemical deposition method.Then,different amounts of Au nanoparticles were deposited on the ZnO surface by photochemical reduction of chloroauric acid to construct Au@ZnO NRAS heterostructures.The standard three-electrode system,in which Au@ZnO NRAS heterostructures and ZnO NRAS were used as the working electrode respectively,was employed to measure the photocurrent-voltage?I-V?,instantaneous photocurrent-time characteristic curves under visible light.Au@ZnO NRAS heterostructures have good photoresponsive activity under visible light.With the increase of Au nanoparticle content,the photocurrent density of Au @ ZnO NRAS heterostructures increases,indicating that the visible-light-driven PEC water splitting of ZnO NRAS is ascribed to the surface plasmon resonance?SPR?of Au nanoparticles under visible light.