Thermal conversion synthesis of Cu2O photocathode and the promoting effects of carbon coating

Simplifying the synthesis of cuprous oxide (Cu2O) photocathode has turned out to be critical for scalable application. Herein, we present a novel thermal conversion approach to synthesize a shell/core structured Cu2O/Cu photocathode. In this method a shell comprising a mixture of CuO and Cu2O is obtained by heating Cu mesh at 500 degrees C in air beforehand, and subsequent annealing in N-2 atmosphere converts the unwanted CuO into Cu2O gradually, which results in the desired Cu2O/Cu structure. A slightly viscous starch sol coats the Cu2O shell as carbon source, after carbonizing under N-2 atmosphere, the Cu2O/Cu is covered with compact carbon films, i.e. C/Cu2O/Cu. Photoelectrochemical experiments reveal that the introduction of carbon layers on Cu2O enhances the photocurrent density from -1.5 to -2.75 mA.cm(-2) at 0 V vs. reversible hydrogen electrode (RHE). Moreover, the deposition of carbon films on Cu2O in this work has little effect on improving the stability. (C) 2015 Elsevier B.V. All rights reserved.