Porous WO3 monolith-based photoanodes for high-efficient photoelectrochemical water splitting

Abstract We report a successful fabrication of low-cost, high-efficient, structurally-rigid, porous WO 3 photoelectrochemical (PEC) catalysts using polystyrene as the template by a sol-gel method and a high-temperature annealing treatment. The scanning electron microscopy and Brunauer-Emmett-Teller surface analysis results indicate that such WO 3 monoliths possess a porous structure and a large specific surface area, which can supply lots of photogenerated charge transfer pathways as well as more surface PEC active sites. Compared with a commercially available WO 3 , our highly porous WO 3 PEC catalysts show an excellent PEC water splitting activity. Particularly, the porous WO 3 photoanodes calcinated in the presence of oxygen atmosphere at 450 °C for 7 h show the best PEC performance exhibiting the photocurrent density of 0.97 mA/cm 2 at 1.23 V versus reversible the hydrogen electrode and the incident photon-to-current conversion efficiency up to 48.9% at 420 nm in 0.5 M Na 2 SO 4 electrolyte under AM 1.5 G irradiation. Such excellent PEC performance is due to the high porosity of the WO 3 , promoting the fast transfer and the separation rate of photogenerated carriers during the PEC water splitting process.