Self‐Assembled Urchin‐Like CuWO4/WO3 Heterojunction Nanoarrays as Photoanodes for Photoelectrochemical Water Splitting.

With attractive visible‐light response and chemical stability, CuWO4 has emerged to be a promising candidate as a photoanode for photoelectrochemical (PEC) water oxidation. In this work, we report a one‐step hydrothermal method to prepare CuWO4‐based films directly grown on a conductive glass substrate from a stable precursor solution. By controlling the reaction duration, CuWO4/WO3 heterojunctions with urchin‐like nanoarray morphology are obtained. The CuWO4/WO3 film obtained with an optimized hydrothermal reaction time exhibits an onset potential of 0.6 V and a photocurrent density of 0.48 mA cm−2 at 1.23 V vs. RHE, which is almost five times that of bare CuWO4. The superior structure of the urchin‐like array with large surface area, optimizing film thickness for adequate light absorption and formation of heterojunctions for efficient charge separation conjointly, contributes to the improved performance as well as robust stability. [ABSTRACT FROM AUTHOR]