| Ever since the first report on photocatalytic water splitting by Fujishima and Honda in 1972,photocatalysis has been considered as a feasible strategy for converting solar energy to sustainable fuels.For decades,increasing efforts have been devoted to developing efficient nanocatalysts for photocatalysis.To realize the industrialization of photocatalytic hydrogen generation,the collection,transportation,and utilization of molecular hydrogen should be taken into consideration,in addition to improving the solar-to-chemical conversion efficiency.This dissertation proposed a strategy for coupling the photocatalytic hydrogen evolution reaction with the hydrogen-transfer hydrogenation reaction,and as a result,the adsorbed hydrogen atoms that were reduced by photo-induced electrons could be utilized in a single system.The TiO2-supported palladium/platinum nanoalloys were designed and synthesized for achieving efficient and selective alkyne semihydrogenation.This dissertation is divided into four chapters:1)Three pivotal steps of photocatalytic organic transformation are introduced,and the design principles of photocatalysts with high performance are summarized.The methodologies for improving selectivity in heterogeneous photocatalytic organic reactions are elaborated shortly afterwards.Then the design of the photo-driven hydrogentransfer alkyne semihydrogenation system is proposed.2)The synthesis process of TiO2 nanosheet-supported PdPt alloys and the characterization of the TiO2-PdxPt1-x?x=0,0.25,0.5,0.75,1?hybrid nanostructures are discussed.3)The TiO2-supported palladium/platinum alloys are employed in the light-driven and water-donating selective alkyne semihydrogenation reaction.The influence of various TiO2-PdxPt1-x compositions on catalytic activity and selectivity is elucidated.After the investigation on the reaction process by control experiments,the possible mechanism for the enhancement of catalytic performance is proposed.4)The future outcome of this research is concluded. |
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