Water reduction by a p-GaInP2 photoelectrode stabilized by an amorphous TiO2 coating and a molecular cobalt catalyst
Abstract
Producing hydrogen through solar water splitting requires the coverage of large land areas. Abundant metal-based molecular catalysts offer scalability, but only if they match noble metal activities. We report on a highly active p-GaInP2 photocathode protected through a 35-nm TiO2 layer functionalized by a cobaloxime molecular catalyst (GaInP2–TiO2–cobaloxime). This photoelectrode mediates H2production with a current density of ~9 mA cm−2 at a potential of 0 V versus RHE under 1-sun illumination at pH 13. The calculated turnover number for the catalyst during a 20-h period is 139,000, with an average turnover frequency of 1.9 s−1. Bare GaInP2 shows a rapid current decay, whereas the GaInP2–TiO2–cobaloxime electrode shows ≤5% loss over 20 min, comparable to a GaInP2–TiO2–Pt catalyst particle-modified interface. The activity and corrosion resistance of the GaInP2–TiO2–cobaloxime photocathode in basic solution is made possible by an atomic layer-deposited TiO2 and an attached cobaloxime catalyst.
J. Gu, Y. Yan, J.L. Young, K.X. Steirer, N.R. Neale, J.A. Turner
Full Text:
http://www.nature.com/nmat/journal/v15/n4/full/nmat4511.html