Improved Performance of Protected CuO Photocathodes Evaluated by Photoelectrochemical Characterizations Using Hydrogen Peroxide

In this report, charge transfer in CuO thin film was photoelectrochemically evaluated using hydrogen peroxide (H2O2) as electron scavenger. We show that photoreduction of H2O2 is more favourable reaction than that of the photocorrosion of CuO at potentials > 0.4 V-RHE so that the photocharge transfer ability of bare CuO film can be evaluated. CuO film fabricated from electrodeposited Cu had more superior photocurrent than that from sputtered Cu measured in H2O2, which indicates better bulk properties. Furthermore, CuO film treated with NH3 solution had superior photocurrent than that of the pristine, suggesting an improvement in surface recombination. Overall, when those CuO films were protected with CdS/TiO2 overlayers into CuO/CdS/TiO2-Pt photocathodes for water splitting reaction, the photocathodes that had higher photocurrent in H2O2 also had superior photocurrent measured under water splitting reaction. The highest photocurrent close to 2 mA.cm(-2) at 0 V-RHE was achieved from the photocathode using NH3-treated CuO film, which present a new performance benchmark for the protected CuO-based photocathode.