Polymer-protected bimetallic nanocluster catalysts having core/shell structure for accelerated electron transfer in visible-light-induced hydrogen generation

A visible-light-induced electron transfer system was constructed by using t ris(bipyridine)ruthenium(III), methyl viologen, EDTA and colloidal metal na nocluster as photosensitizer, electron relay, sacrificial electron donor an d reductive catalyst, respectively. Polymer-protected Au, Pt, Pd, Rh and Ru monometallic, and Au/Pt, Au/Pd, Au/Rh and Pt/Ru bimetallic nanocluster cat alysts were prepared as colloidal dispersions by alcohol-reduction, and app lied to the catalysts for the above reaction. The rate of electron transfer from methyl viologen cation radical to the metal nanocluster catalyst is p roportional to the hydrogen generation rate at a steady state. All the elec trons accepted by metal nanocluster catalysts are used for the hydrogen gen eration. Both electron transfer and hydrogen generation rates increase when the colloidal dispersions of bimetallic nanoclusters are used in place of the corresponding monometallic nanoclusters. An Au-core/Rh-shell structure has been suggested by UV-Vis spectrum measurement for Au/Rh bimetallic nano clusters.