Structure-Controlled Synthesis, Growth Mechanism And Catalytic Performance Of Bi₂S₃-Based Nanocrystals And PtCu₃Alloys

Metal sulfide nanocrystals and metal alloys are very important materials and commonly used as catalysts with high catalytic performance. In this paper,2D Bi2S3networks and Bi2S3/TiO2heterostructures have been synthesized and the growth mechanisms were proposed. In the mean time, the electrocatalytic and photocatalytic performances were also investigated respectively. In addition, Pt-Cu hollow structure was rapidly prepared by simple one-pot synthesis method.In chapter1, the synthetic methods, growth mechanisms and practical applications of Bi2S3-based nanocrystals were introduced and the recent progress of Pt-Cu alloys have been reviewed.In chapter2, a two-step topotactic transformation was designed to fabricate Bi2S3nanorod network films taking advantage of the layer-structural relationships among BiI3, BiOI and Bi2S3. In the first step, BiOI nanosheets on FTO glass were in situ fabricated using layered Bii3as sacrificial templates through chemical vapor deposition (CVD). In the second step, BiOI nanosheets were sulfurized via hydrothermal process, where the topotactic transformation from BiOI nanosheet to Bi2S3nanorod network was realized. Moreover, the optimized Bi2S3network thin film serving as counter electrode (CE) for CdSe QDSCs exhibited a record conversion efficiency of2.20%, which was remarkably better than that of Pt (1.36%), showing that Bi2S3networks have high electrocatalytic activity. Bi2S3networks decorated with conductive Pt particles have also been studied to improve the conductivity and conversion efficiency with increasement of30%.To optimize interfacial properties, reduce interface defects and simplify fabrication process, Bi2S3/TiO2heterostructures were prepared by one-pot route in chapter3. The charge transfer was evaluated by photodegradation of methyl orange under visible light irradiation. The results showed that TiO2nanoparticles grew in situ on the (010) surface of crystalline nanorods when using metal organic precursor of Bi(S2CNEt2)3as Bi source, the heterostructures had defect-free interfaces with epitaxial relationship of Bi2S3(011)//TiO2(101) and showed effective charge transfer exhibiting improved photocatalytic activity, superior to that samples with defects at interfaces via two-step method.In chapter4, cage-like PtCu3hollow nanostructure was rapidly prepared by simple one-pot synthesis method using trrans-PtCl2(NH3)2as Pt source and CuBr as Cu source in OAm. The formation mechanism of hollow structures was proposed. The PtCu3hollow structure was sensitive to the temperature. Too high temperature would accelerate the diffusion rate of atoms, resulting in the collapse of the hollow structure.