Synthesis On PPy-PANI/TiO₂、4NP-rGO/TiO₂and BiOBr_xI_yCl_1-x-y And Their Studies Of Photocatalytic Properties

How to harness the unnature pollutants with high toxicity and lowconcernttration is an unavoidable task. Owing to effectively, rapidly andenvironmentally friendly, semiconductor photocatalysis have became the maintechniques to remove the pollutants. Tiranium dioxide (TiO2) is chemically stable,nontoxic, and cheap. However, the low solar energy conversion efficinency and thehigh recombination rate of photogenerated electrons and holes limit its practicalapplications.From the preparation of high-performance photocatalysts, following researchwork based on two aspects. The fist one is making efforts to extend the lightabsorption of TiO2into the visible region and increase its photocatalytic activity usingconducting polymer doping. Combing with the molecular imprinting technique, alsowith rGO, we can enhance its selective adsorption and photocatalytic ability towardsthe certain pollutants. The other is to develop new photocatalysts. The first strategyhas been studied deeply, but it still can not satisfy the requirement for practicalapplication. We study the photocatalytic performance of BiOX under visible lightirradiation. The details are summarized as follows:(1) Preparation and research of Conductive polypyrrole-polyaniline/TiO2nanocomposites (PPy-PANI/TiO2). PPy-PANI/TiO2was prepared by in situ oxidativecopolymerization of pyrrole and aniline monomers in the presence of TiO2. Forcomparision studies, polypyrrole/TiO2(PPy/TiO2) and polyaniline/TiO2(PANI/TiO2)were also prepared. In contrast PPy/TiO2and PANI/TiO2, PPy-PANI/TiO2exhibitsobvious absorption in the visible-light range, and is much superior to PPy/TiO2andPANI/TiO2in thermal stability. It is found that PPy-PANI/TiO2performs well in thevisible-light photocatalytic degration of4-nitrophenol. The optimized pyrrole: aniline:TiO2molar ratio for best performance is0.75:0.25:100. The efficacy ofPPy-PANI/TiO2is attributed to its conductivity, conjugated structure, as well as to thesynergy amidst polypyrrole and TiO2.(2) Facile one-step sol-hydrothermal preparation of rGO-TiO2photocatalysts viasurface molecular imprinting technique which taking4-nitrophenol as target molecule,tertrabutyl orthotitanate as titanium source as well as the precursor of functionalmonomer, while adding the solution of GO. The optimal ratios between rGO and TiO2was GO: TiO2=0.002:1, which we called4NP-rGO6/TiO2. Compared to nomimprinted NIP-rGO/TiO2, the molecularly imprinted4NP-rGOx/TiO2（x=3、6、9）shows a much higher adsorption capacity and selectivity toward the4NP. Theenhancement interms of adsorption capacity and selectivity can be attributed to thechemical interaction between target molecules and imprinted cavities, as well as sizematching between imprinted cavities and target molecules.(3) Preparation and research of of BiOBrxIyCl1-x-yphotocatalysts. Ethylene glycol(EG) as solvent, using solvothermal synthesis method to preparate BiOBrxIyCl1-x-y.For comparision studies, BiOX (X=Br, I, Cl) and BiOBrxI1-x, BiOBrxCl1-x, BiOIxCl1-xwere also made. It is found that BiOBr0.2I0.6Cl0.2performs well in the visible-lightphotoreduction of Cr6+, though its adsorbation cannot match with BiOX (X=Br, I, Cl).Belonging to n-type semiconductor, we full use BiOBr0.2I0.6Cl0.2to photoreduction ofCr6+taninted solutions.