Facile synthesis of flexible and scalable Cu/Cu₂O/CuO nanoleaves photoelectrodes with oxidation-induced self-initiated charge-transporting platform for photoelectrochemical water splitting enhancement

Photoelectrochemical hydrogen production is considered a promising candidate for artificial photosynthesis. Herein, a facile oxidation method is proposed for fabricating flexible and scalable Cu/Cu₂O/CuO nanoleaves photoelectrodes. The process creates a thin Cu₂O layer at the oxygen-lacking interface between Cu and CuO ingredients and can act as a self-initiated charge-transporting platform in photoelectrochemical water splitting. The proposed Cu/Cu₂O/CuO nanoleaves have been demonstrated as a promising photoelectrode material superior to that of similar photoelectrodes fabricated by other methods. Despite the impressive performance, the Cu/Cu₂O/CuO photoelectrodes are subjected to annealed at different temperatures and, the Cu/Cu₂O/CuO photoelectrode annealed at 100 °C displays a remarkable hydrogen evolution of 4.76 μmol/hcm², in comparison. A possible mechanism for such improvements is suggested based on the self-initiated Cu₂O layer and surface reconstruction with post-annealing. Namely, the charge transport layer prevents photocorrosion by improving the photostability and reducing the grain boundaries by increasing the size of the particles, thereby enhancing efficiency via fast charge carrier transfer. Accordingly, our exploration introduces the self-initiated charge-transporting platform and flexible photoelectrodes for the improvement of photoelectrochemical hydrogen production based on the Cu/Cu₂O/CuO nanoleaves.