Plasmonic Au nanoparticles sensitized ZnO/CuO heterostructure for efficient photoelectrochemical water splitting

Hydrogen production via photoelectrochemical water splitting is a promising route to convert solar energy into chemical fuel, reducing energy crises and boosting environmental health. Here, we report the fabrication of ternary ZnO/CuO/Au heterostructures by electrodeposition and chemical bath deposition methods. The heterojunction formed can enhance the optical absorption, and photogenerated electrons and holes can efficiently separate due to the built-in electric field, which reduces recombination losses. Au plasmons incorporated in ZnO/CuO heterojunction enhance the optical absorption and promote fast free charge carrier transport at the interface through the surface plasmon resonance (SPR) effect. The ZnO/CuO/Au photoanode exhibits a photocurrent density of 1.08 mA/cm2 at 1.6 V Vs RHE, two times higher than pristine ZnO. The ZnO/CuO/Au photoanode exhibits the lowest charge transfer resistance of 600 Ω from electrochemical impedance spectra(EIS). The Bode plot revealed that the most extended lifetime of 8.69 μs is observed for ZnO/CuO/Au photoanode, which is larger than pristine ZnO. The synthesized thin films showed good stability and reusability for the photooxidation of water.