The Preparation And Electrocatalytical, Photocatalytical Performances Of Composite Materials Derived From Layered Double Hydroxide Film

Layered double hydroxides films(LDHs films) not only have LDHs’ characteristics of unique layered structure, adjustable performance of laminate cationic, exchangeable performance of interlayer anion and memory effect, but also have films’ characteristics of low loss rate, easy recovery and easy devices. Owing to the speci?c structure and versatility in chemical composition, LDHs film has been widely used as semiconductor materials in the ?elds of electrocatalysis and photocatalysis. This thesis is aimed at LDHs-based thin film composite material to design and optimize their electrocatalytic and photocatalytical properties. The details are summarized briefly as follows:1. RGO/Zn-Cr LDHs film composite materials were prepared by electrodepositing Zn-Cr LDHs film on the gold electrode surface and then electroreducing GO on the surface on Zn-Cr LDHs film by cyclic voltammetry. The processes of deposition were characterized by combination of electrochemistry and quartz crystal microbalance(QCM) techniques. The structure and electrochemical properties of modified electrode were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and cyclic voltammetry. The results shows the Zn-Cr LDHs film has the morphologies of porous structure and transparent RGO sheets distributed on Zn-Cr LDHs surface. EIS indicated that the presence of RGO is effective in enhancing the rate of electron transfer. The electrochemical behaviors of bisphenol A(BPA) on the modified electrodes were investigated. The results showed the modified electrode with RGO/Zn-Cr LDHs has better electrocatalytic performance than that of Zn-Cr LDHs. Under optimized conditions, the linear range of RGO/Zn-Cr LDHs modified electrode was 2.0×10-7~1.0×10-4 mol/L, and showed good reproducibility performance. The modified electrode exhibits broad application prospects in the detection of organic pollutants in water.2. A composite material based on gold nanoparticles(AuNPs) and Zn-Cr LDHs was prepared by one-step electrosynthesis, directly onto the FTO electrode surface. The resulting material(AuNPs/Zn-Cr LDHs) was characterized by XRD, SEM, UV-Vis diffuse reflectance and by electrochemical techniques. The results showed that Au nanoparticles were successfully loaded on Zn-Cr LDHs’ surface uniformly. The photocatalytic activity of AuNPs/Zn-Cr LDHs toward the degradation of dye was better than that of Zn-Cr LDHs. The enhanced photocatalytic activity could be attributed to the great adsorptivity of dyes, the extended photoresponse range, the negative shift in the Fermi level of AuNPs/Zn-Cr LDHs, and the high migration efficiency of photoinduced electrons, which may effectively suppress the charge recombination.3. The impacts of different types of surfactants on the Zn-Cr LDHs film deposition process and performances were investigated. The results of SEM, XRD, DRS and EIS characterizations demonstrated that the kinds of surfactants affected the Zn-Cr LDHs films’ morphology and crystalline, broaden the range of light absorbing, enhanced the mobility of photo-generated electrons and improved the photocatalytic properties of materials.