Photoelectrochemical hydrogen production is a promising and cost-effective strategy to provide clean and sustainable fuel. Due to its excellent electrical and optical properties, tungsten trioxide (WO3) is one of the most studied electrode materials in this field, and it is well known that the incorporation of pores into the semiconductor can improve its photoelectrochemical performance. Using a facile and scalable template-assisted sol–gel technique, porous WO3 thin films were tailored by simply varying the number of dip coating cycles. By crystallizing these films at 400 °C, a β* β *-orthorhombic/γ* γ *-monoclinic crystal structure and an average surface area of 32 m2 g−1 were obtained. By optimizing the layer thickness of these photoanodes on fluorine-doped tin oxide, photocurrents of up to 3. 3 mA cm−2 at 1. 23 VRHE (in 0. 1M H2SO4, pH = 0. 71) were achieved without the use of any co-catalysts or sacrificial agents. Our photoelectrodes also showed highly reproducible photocurrents, and their high stability was proven in cycling tests, long-term measurement and post-photoelectrochemical characterization. Our work represents a very simple preparation optimization to achieve high-performing WO3 photoanodes for photoelectrochemical applications.
Mayer et al. (Wed,) studied this question.