rGO decorated ZnO/CdO heterojunction as a photoanode for photoelectrochemical water splitting

[Display omitted] A novel ternary photoanode of ZnO/CdO/rGO was successfully designed and fabricated by simple method. The photoanode not only extends the visible light absorption range and increases photocurrent density but also enhances IPCE value and solar conversion efficiency, which is attributed to the effective separating of photogenerated electron-hole pairs and rapid electron transfer caused by rGO modification., which in turn enhances PEC water splitting efficiency. A ternary photoanode of ZnO/CdO heterojunction decorated with reduced graphene oxide (rGO) was firstly fabricated by electrochemical deposition and thermal decomposition that is simple and effective compared with other method reported in literature. The structure and morphology of the photoanode were systematically characterized by various spectrum technologies. The photoanode expands the visible light absorption range to 428 nm, the photocurrent density reaches 1.15 mA·cm−2 at 1.23 V (vs. RHE) that is 3 times and 1.85 times of pure ZnO (0.38 mA·cm2) and ZnO/CdO (0.62 mA·cm2) photoanodes. The highest IPCE value reaches 42.63% at 380 nm. The enhancement is attributed to the architecture of semiconductor heterojunctions and the decoration of rGO nanosheets, the former promotes charge separation, while the latter accelerates electron transfer thus both synergistically enhance PEC water splitting efficiency. Here fabricated photoanode has never been reported before, only Cd and other metal elements doped ZnO photoanodes were reported in the literature.