In situ formation of CuWO4/WO3 heterojunction plates array films with enhanced photoelectrochemical properties

•CuWO4/WO3 heterojunction photoanode was fabricated through a facile method.•The in situ formation of heterojunction optimizes the charge transfer.•CuWO4/WO3 heterojunction plates array films exhibited high photocurrent density.•The low-dimensional heterojunction structures provide a promising photoanode.

CuWO4/WO3 heterojunction photoanode based on WO3 plates arrays and CuWO4 nanoparticles was fabricated to enhance the photoelectrochemical performance. WO3 plates array films were prepared through a simple hydrothermal method, then a facile dipping-annealing process was employed to fabricate CuWO4/WO3 films. The crystal structure, morphology, composition and optical properties of the samples were analyzed by X-ray diffraction, scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy and UV–vis spectrometry. As-prepared CuWO4/WO3 heterojunction films achieved a photocurrent density of 1.21 mA/cm2 at 1.5 V vs. Ag/AgCl, which was almost 2-fold higher than that of the pure WO3 film (0.64 mA/cm2) under illumination. The enhanced photocurrent was attributed to the extension of visible light response, increased carriers density, effective separation at the interface of heterojunction and better electron transport properties, which were confirmed by Mott–Schottky and electrochemical impedance spectroscopy. This study reveals that the low-dimensional morphological structure and heterojunction structure are expected to provide a promising photoanode for water splitting.