Core/shell-structured bimetallic nanocluster catalysts for visible-light-induced electron transfer

It has been found that the bimetallic nanoclusters often have so-called cor e/shell structure if they are prepared by alcohol-reduction of two kinds of noble metal ions in the presence of a water-soluble polymer like poly(N-vi nyl-2-pyrolidone) (PVP), and that the core/shell structured bimetallic nano clusters have much higher catalytic activity than the corresponding monomet allic nanoclusters. Here, several kinds of monometallic and bimetallic nano clusters are synthesized by the similar method, and the catalyses are measu red. Thus, the colloidal dispersions of Au, Pt, Pd, Ph, and Ru monometallic , and Au/Pt, Au/Pd, Au/Rh, and Pt/Ru bimetallic nanoclusters were synthesiz ed and applied as the catalysts for visible-light-induced hydrogen generati on. The core/shell structures are analyzed mainly by UV-vis spectra. The ra te of electron transfer from the methyl viologen cation radical to the meta l nanoclusters is proportional to the hydrogen generation rate at the stead y state. All the electrons accepted by the metal nanoclusters are used for the hydrogen generation. Both electron transfer and hydrogen generation rat es increase when the bimetallic nanoclusters are used in place of the corre sponding monometallic nanoclusters. The most active catalysts were Au/Rh an d Pt/Ru bimetallic nanoclusters.