The Preparation And Photocatalytical Performance Of Composite Materials Derived From Layered Double Hydroxide

This thesis is aimed at the existence proplem in the current photocatalytictechnology, such as low photocatalytic efficiency, low utilization rate of solar energy.The target is to develop the novel composite photocatalyst with visible light response.Hydrotalcite was chosed as a carrier for the load of the semiconductor to improve thephotocatalytical performance.The main research content is as follows:1. By a simple hydrothermal method to prepare a hydrotalcite-likenanostructured CdS/CoAl-LDH photocatalyst, which shows high efficiency incatalyzing decomposition of organic compounds under visible light. The highphotocatalytic efficiency can be attributed to the interfacial CdS doping, whichimproves visible light activity, enhances light harvesting and charge separation, whichreduces the photo-holes and electrons recombination rate. We expect thisnanocomposite to have other interesting applications.2. By a facile memory restructuring method to prepare Ag/AgBr/MgFe LDHsnanocomposites by adding NaBr aqueous solution to a suspension of MgFe-MMO.The Ag/AgBr nanoparticles are anchored on MgFe LDHs nanosheets, thenanocomposites show enhanced effective segregation of the photo-holes and electronsand high visible-light photocatalytic activity for organic pollutants. The excellentphotocatalytic activity of such nanocomposites could have wide applications inwastewater treatment.3. NanoAg loaded ZnAlCe LDHs have been synthesized by co-precipitation andphotochemical reduction method. XRD, SEM, EDS, N2adsorption, UV-vis analysisand the electrochemical analysis were adopted to investigate the structure, surface,micromorphology, photoresponsive and electrochemical properties of theas-synthesized samples. The combination of ZnAlCe LDHs and nanoAg introducessome properties of Ag into photocatalysis such as excellent conductivity andcontrollability. Remarkable enhancement in the degradation of rhodamine B (RhB)reaction was observed on as-prepared Ag/ZnAlCe LDHs compared with pure ZnAlCeLDHs. The enhanced photocatalytic activity could be attributed to high specificsurface, extended photoresponding range, the negative shift in the flat-band potentialsand the high migration efficiency of photoinduced electrons, which may suppress thecharge recombination effectively.