Advanced one dimensional plasmonic photocatalysts

Semiconductors involved in photocatalysis have attracted considerable interest, owing to their great potential in the fields of environmental remediation, and renewable and clean energy exploitation. The limitations of ineffective sunlight utilization and low separation efficiency of electron-hole pairs of the commonly used semiconductor photocatalysts such as ZnO, Cu2O, CdS, and Ag2S, however, hinder their practical applications. To construct metal/semiconductor heterostructures through modification of such photocatalysts with novel plasmonic metals has been considered as a promising strategy for the improvement of the corresponding photocatalytic activity. Compared to other noble metals, one-dimensional (1D) Ag nanowires (Ag NWs) are more attractive because of their higher electrical and thermal conductivity, antibacterial characteristics, lower cost, nontoxicity, and wealth of optical and photoelectrochemical properties directly related to their geometry-dependent surface plasmon resonances, which makes them very popular for fabrication of advanced semiconductor/noble metal nanophotocatalysts. In this doctoral work, semiconducting metal oxides and metal sulfides such as ZnO, Cu2O, CdS and Ag2S were chosen as examples for constructing semiconductor/noble metal photocatalysts. The compositon and structure of the resultant composites were characterized, and the optimum ratio of metal oxides/sulfides to Ag in the metal/semiconductor heterostructures showing excellent photocatalytic performance was investigated. The resultant 1D Ag@ZnO and Ag@Cu2O core-shell nanowires prepared by a facile and general ambient strategy exhibited better photocatalytic performance and stability during organic contaminants photodegradation compared to zero-dimensional Ag@ZnO and Ag@Cu2O core-shell nanoparticles and pure ZnO (/Cu2O) nanocrystals under irradiation by solar light. The coreshell 1D hierarchical Ag@CdS nanowires also exhibited better photocatalytic performance than pure CdS. In addition, the 1D/two-dimensional (2D) hierarchical Ag-Ag2S nanowire/nanosheet heterostructures showed excellent dye adsorption performance, although the catalytic activity was not significantly enhanced. Furthermore, they also exhibited great potential in lithium ion batteries and surface-enhanced Raman spectroscopy (SERS) detection of pollutants. This thesis will not only provide a facile and general approach to preparing 1D Ag@metal-oxide/sulfide hetero-nanostructured photocatalysts, but also explore the potential applications of such 1D heterostructures in energy-related fields.