Cu2ZnSnS4-Au heterostructures: Toward green photocatalytic materials active under visible light

Solar energy is a potentially limitless source of clean power, but needs an effective means of conversion and storage to be feasible. Semiconductor-metal heterostructures have been studied as potential photocatalysts for use in solar-to-chemical energy conversion as a way of converting solar energy. This thesis examines pathways towards the synthesis of Cu2ZnSnS 4-Au, a novel semiconductor-metal heterostructure. Cu2ZnSnS 4 (CZTS) is attractive for use in this area because it has a narrow bandgap (1.5 eV) and is made of relatively earth-abundant and non-toxic elements.;There are four methods studied in this thesis for the fabrication of CZTS-Au, two use AuCl3 as a precursor and two utilize pre-formed Au nanoparticles. Both precursors were studied under thermal and photochemical deposition conditions. The resulting products were characterized to determine the most effective pathway to fabricate these heterostructures. AuCl 3 under thermal deposition conditions proved to be the best pathway due to the well-defined monodisperse product.;We also studied whether Au metal islands could be effectively removed while leaving the CZTS nanocrystals intact. The results of this experiment were mixed. It does seem that smaller Au nanoparticles are removed, but larger amalgams remain attached to the CZTS nanorods and remain inseparable despite numerous efforts.;Finally, CZTS-Au was tested for photocatalytic activity using the model system of methylene blue reduction. CZTS-Au was found to convert methylene blue to leucomethylene blue at a much higher rate than bare CZTS. These results open up a new area of CZTS-metal heterostructures for the purpose of finding greener photocatalysts for solar-to-chemical energy conversion.