Design Of High Efficiency Photocatalytic Materials And Its Application In Hydrogen Production From Photolysis Of Water

Nowadays, the world is facing serious energy and environmental problems, so itis very urgent to produce a clean and sustainable energy using renewable energysource to solve such problems. Hydrogen energy has been regarded as the mostpromising alternative energy resource in21st century by the majority of scholarsaround the world. Among various hydrogen production paths, the photocatalytic watersplitting technique is increasingly under the spotlight, due to the fact that the system issimple and sustainable, and solar energy could be utilized directly. Hence, thedevelopment of the necessary semiconductor photocatalysts has undergoneconsiderable research.In this paper, several high efficient photocatalytic materials were designed tosolve the existing problem of photocatalysis, which mainly includes the material ofC60-CdS/TiO2,(C60-RGO)/CdS, TiO2/SiO2and TiN. These samples werecharacterized by XRD, TEM, BET, XPS, PL fluorescence spectrum, UV-vis diffuseabsorption spectra and so on. As well as their photocatalytic performance wasevaluated by water splitting into hydrogen. The research was mainly composed of thefollowing four parts:(1) The C60Embedded Mesoporous CdS/TiO2photocatalytic materials(C60-CdS/TiO2) was synthesized by Evaporation Induced Self-Assembly (EISA)method and ion-exchange method, and characterized by XRD, TEM, BET, XPS andso on. Its photocatalytic activity for hydrogen evolution was investigated in aqueousNa2S and Na2SO3solution under visible light irradiation (λ=420nm, LEDs). Theresults indicated that the C60-CdS/TiO2composite photocatalyst was more active andstable for hydrogen producing compared with CdS/TiO2photocatalyst materials,mainly due to the excellent electron transfer effect of C60and the structure ofmesoporous materials. The optimal mass ratio C60to TiO2was0.5wt.%.(2) The CdS nanorods loaded onto C60-decorated GO sheet hybrid ((C60-RGO)/CdS) was prepared by a solvothermal route. The photoactivities for H2production of CdS nanorods coupled with various carbon nanostructured materials(such as C60, GO, C60-GO) were examined using methanol as sacrificial agent Undervisible light irradiation (λ=420nm). It has been found that the photoactivity forhydrogen production and photostability of CdS nanorods can be significantlyenhanced by C60-decorated GO sheet coupled. Experimental results suggest that theC60-decorated GO sheet as a novel carbon nanostructured material could be morebeneficial for its best charge carriers transfer and the strong adsorption to the reactantmolecules because of high specific surface area of GO. As a result, the activity ofhydrogen evolution was promoted.(3) The TiO2Quantum Dots embedded in SiO2photocatalysts (TiO2/SiO2) weresuccessfully synthesized by a post-synthesis step via Ti-alkoxide hydrolysis in thechannel of supporting material-SiO2foams. Results from characterizations showedthat the supporting material-SiO2foams have a large pore size and TiO2had a smallcrystalline size (below5nm, Quantum Dots size) which was well dispersed on thechannel of SiO2foams. Experimental results show that calcination in air of thecomposites up to900°C did not change the nanocrystal phase, indicating that theanatase TiO2grains in the foam structures have a relatively high thermal stability andproper pore diameter allows controlling the size of obtained TiO2particles (5-8nm).The optimal TiO2loading content was found to be60mol%under900°C calcinationcondition, giving an expression that the higher loading capacity of SiO2foams.(4) This part of research is based on the part (3). The TiO2/SiO2hybrid materialswere further nitrided in ammonia atmosphere. As a result, highly dispersed TiNquantum dots which embedded in SiO2foams (TiN/SiO2) were successfullysynthesized. The research of TiN system is further proceeded.