fig3

Figure 3. PEC splitting of water vapor using WO₃ photoanode: (A) dependence of photocurrent response on the applied voltage and (B) time-dependent O₂ production rate over the photoanode at an applied voltage of 1.2 V vs. cathode (wavelength: 453 nm, irradiance: 7 mW cm^-2, and irradiation area: 16 cm²). Schematic illustrations of the interfacial structure of WO₃ photoanodes in a gas-phase atmosphere: (C) bare WO₃, where proton transport is the rate-determining step and (D) PEC triple-phase boundary formed by a thin PFSA ionomer film coating on the surface. Reproduced from ref.^[25], Copyright 2018 Amano et al.^[25].