Cu ions intercalated GO/Cu2O photocathode-enabled promotion on charge separation and transfer for efficient photoelectrochemical water splitting

The development of cuprous oxide (Cu2O) photocathode for photoelectrochemical (PEC) water splitting confronts charge recombination and photocorrosion. Herein, a facile strategy for wrapping Cu2O photocathode with Cu ions intercalated graphene oxide (Cu-GO) was proposed to realize efficient PEC water splitting. The intercalating GO with Cu ions could reduce the bandgap and enhance the carrier mobility of Cu-GO. The as-formed Cu-GO could suppress surface charge recombination and accumulation of the Cu-GO/Cu2O photocathode by improving the interfacial charge transfer, which strengthens electron extraction and restrains photocorrosion. The Cu-GO/Cu2O photocathode achieved a high photocurrent density of − 7.03 mA cm−2 (at 0 V vs. RHE) under AM 1.5 G illumination and excellent photostability for PEC water splitting. This work provides a simple way to design Cu2O-based photocathodes with reliable charge transfer layers for efficient PEC water splitting.