Self-activated Rh–Zr mixed oxide as a nonhazardous cocatalyst for photocatalytic hydrogen evolution†

Abstract

Efficient, robust and environmentally friendly cocatalysts for photocatalysts are important for large-scale solar hydrogen production. Herein, we demonstrate that a Rh–Zr mixed oxide is an efficient cocatalyst for hydrogen evolution. Impregnation of Zr and Rh precursors (Zr/Rh = 5 wt/wt%) formed RhZrO _x cocatalyst particles on Al-doped SrTiO ₃, which exhibited 31× higher photocatalytic water-splitting activity than a RhO _x cocatalyst. X-ray photoelectron spectroscopy proved that the dissociation of Cl ⁻ ions from preformed Rh–Cl–Zr–O solid led to formation of the active phase of RhZrO _x , in which the Zr/Rh ratio was critical to high catalytic activity. Additional CoO _x loading as an oxygen evolution cocatalyst further improved the activity by 120%, resulting in an apparent quantum yield of 33 (±4)% at 365 nm and a long durability of 60 h. Our discovery could help scale up photocatalytic hydrogen production.

Abstract

An efficient, robust and environmentally friendly Rh–Zr mixed oxide formed though the activation of Rh–Cl–Zr–O solid efficiently functions as a HER cocatalyst on Al-doped SrTiO ₃.