| Solar energy conversion is one of the most intensively studied areas of modern science, in the face of ever depleting fossil fuel stocks and increasing energy demands. One approach is to create photo-catalytic systems utilizing solar energy for water splitting, based on catalyst-decorated semiconductor nanostructures. Nanomaterials provide a number of advantages for photocatalysis over bulk counterparts, like higher surface-to-volume ratio. In particular nanorods offer several advantages for the charge separation as compared to spherical nanoparticles, including the lower exciton binding energy and the ability to control the distance between the reaction sites. We decorate colloidal CdS nanorods with extremely small, subnanometer sized Pt clusters, and demonstrate their use for photocatalytic hydrogen production. We also show highly selective decoration of CdS nanorods with uniform, relatively large 5 nm mean size Pt nanoparticles, with a remarkably high 90% yield of samples decorated with exactly one Pt particle per rod. Further studies employ colloidal CdSe/CdTe hetero-structures. CdSe/CdTe nanodumbbells are synthesized in organics medium, transferred to aqueous medium by ligand exchange, and light-induced Pt decoration experiments are conducted using different laser excitation wavelengths in order to achieve size selective metal deposition. |
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