Oxygen\nVacancies Enhanced WO₃/BiVO₄ Photoanodes Modified\nby Cobalt Phosphate for Efficient Photoelectrochemical\nWater Splitting

Abstract

Efficient\ncharge separation is critical for improving the photoconversion\nefficiency in photoelectrochemical (PEC) water splitting. Herein,\nwe develop an oxygen vacancy (OV)-enriched WO₃/BiVO₄ photoanode modified by cobalt phosphate (CoPi) cocatalysts\nfor significant enhancement in PEC performances. Experimental results\nand theoretical calculations based on density functional theory demonstrate\nthat the OV that penetrated from WO₃ to the BiVO₄ layer will act as a highway for the charge transfer between semiconductor\ninterfaces. Specifically, the existence of oxygen vacancies can not\nonly tune the electronic structure and decrease the energy barrier\nfor the stepped hole transfer but also improve the hydrophilic ability\nof the electrode. Meanwhile, CoPi as oxygen evolution cocatalysts\ncan further accelerate transport of holes to the electrode surface\nfor the oxidation of water. Benefitted from this, the (WO₃/BiVO₄)-OV/CoPi photoanode yields a photocurrent of 2.3\nmA cm^–2 at 1.23 V vs RHE with long-time stability.\nThis work will provide a universal strategy for rational designing\nand fabricating highly efficient PEC water splitting systems.