ZnSe Nanorods as Visible-Light Absorbers for Photocatalytic and Photoelectrochemical H2 Evolution in Water

A precious-metal- and Cd-free photocatalyst system for efficient H-2 evolution from aqueous protons with a performance comparable to Cd-based quantum dots is presented. Rod-shaped ZnSe nanocrystals (nanorods, NRs) with a Ni(BF4)(2) co-catalyst suspended in aqueous ascorbic acid evolve H-2 with an activity up to 54 +/- 2 mmol(H2) g(ZnSe)(-1) h(-1) and a quantum yield of 50 +/- 4% (lambda=400nm) under visible light illumination (AM1.5G, 100 mWcm(-2), lambda > 400 nm). Under simulated full-spectrum solar irradiation (AM 1.5G, 100 mWcm(-2)), up to 149 +/- 22 mmol(H2) g(ZnSe)(-1) h(-1) is generated. Significant photocorrosion was not noticeable within 40 h and activity was even observed without an added co-catalyst. The ZnSe NRs can also be used to construct an inexpensive delafossite CuCrO2 photocathode, which does not rely on a sacrificial electron donor. Immobilized ZnSe NRs on CuCrO2 generate photocurrents of around -10 mu A cm(-2) in an aqueous electrolyte solution (pH 5.5) with a photocurrent onset potential of approximately +0.75V vs. RHE. This work establishes ZnSe as a state-of-the-art light absorber for photocatalytic and photoelectrochemical H-2 generation.