A conductive ZnO–ZnGaON nanowire-array-on-a-film photoanode for stable and efficient sunlight water splitting

Abstract

We report highly stable and efficient sunlight water splitting on a ZnO–ZnGaON nanowire-array-on-a-film photoanode without the assistance of any co-catalyst. The single crystalline ZnO–ZnGaON nanowire-array-on-a-film photoanode was synthesized via a high-temperature vapor-phase diffusion reaction of gallium (Ga) and nitrogen (N) on a single crystal domain ZnO nanowire-array-on-a-film structure. The synthesized ZnO–ZnGaON photoanode offers visible light absorption through N incorporation, improved electrical conductivity via Ga incorporation, and structural advantages with the high-aspect-ratio nanowire array. Compared to the chemically unstable ZnO nanowire photoanode, the ZnO–ZnGaON nanowire photoanode significantly improves the anti-photocorrosive ability for water splitting. A highly stable photocurrent density of ∼1.5 mA cm⁻² is obtained with the ZnO–ZnGaON nanowire photoanode at an applied bias of 0.8 V_RHE under continuous sunlight illumination over five hours without noticeable degradation.