1 research outputs found
Enabling Overall Water Splitting on Photocatalysts by CO-Covered Noble Metal Co-catalysts
Photocatalytic
overall water splitting requires co-catalysts that
efficiently promote the generation of H<sub>2</sub> but do not catalyze
its reverse oxidation. We demonstrate that CO chemisorbed on metal
co-catalysts (Rh, Pt, Pd) suppresses the back reaction while maintaining
the rate of H<sub>2</sub> evolution. On Rh/GaN:ZnO, the highest H<sub>2</sub> production rates were obtained with 4ā40 mbar of CO,
the back reaction remaining suppressed below 7 mbar of O<sub>2</sub>. The O<sub>2</sub> and H<sub>2</sub> evolution rates compete with
CO oxidation and the back reaction. The rates of all reactions increased
with increasing photon absorption. However, due to different dependencies
on the rate of charge carrier generation, the selectivities for O<sub>2</sub> and H<sub>2</sub> formation increased in comparison to CO
oxidation and the back reaction with increasing photon flux and/or
quantum efficiency. Under optimum conditions, the impact of CO to
prevent the back reaction is identical to that of a Cr<sub>2</sub>O<sub>3</sub> layer covering the active metal particle