A 3D triple-deck photoanode with a strengthened structure integrality: Enhanced photoelectrochemical water oxidation

WO₃/BiVO₄ is one of the attractive Type II heterojunctions for photoelectrochemical (PEC) water splitting due to its well-matched band edge positions and visible light harvesting abilities. However, two light absorption components generally suffer from poor charge collection and cannot be efficiently utilized because of non-ideal interfaces. Herein, a triple-deck three-dimensional (3D) architecture was designed through a one-step shaping process with an additional stress relaxation WO₃ underlayer. The final photoanodes showed a promising photocurrent density of 5.1 mA cm^-2 at 1.23 V vs. RHE under AM 1.5G illumination. Using the uniformly distributed oxygen evolution co-catalyst (OEC) layer as the outer most shell of the WO₃/BiVO₄/OEC triple-deck 3D structure with a dense WO₃ underlayer, the water splitting efficiency was improved dramatically by facilitating the charge transfer process at the electrode/electrolyte interface.