Ag-Boosted CoOx/BiVO4 p–n heterojunction for efficient photoelectrochemical water splitting

Abstract

A ternary BiVO₄/CoO_x/Ag photoanode was developed via hydrothermal synthesis and photodeposition for efficient solar water splitting. The synergistic integration of p-type CoO_x and plasmonic Ag enhances charge separation through p–n heterojunction formation, increases carrier density, and improves visible-light harvesting and hole transfer kinetics. The modified photoanode achieves a high photocurrent density of 3.2 mA cm⁻² at 1.23 V vs. RHE, with 85% charge injection efficiency and excellent stability over 3 h. Gas evolution confirms near-theoretical H₂:O₂ stoichiometry and faradaic efficiency >88%, demonstrating highly efficient and stable overall water splitting.