Affiliation:
1. Department of Chemistry Education and Optoelectronic Convergence Research Center Chonnam National University Gwangju 61186 Republic of Korea
2. Pohang Accelerator Laboratory Pohang University of Science and Technology (POSTECH) Pohang 37673 Republic of Korea
3. Chemistry and Nanoscience Center National Renewable Energy Laboratory Golden CO 80401 USA
Abstract
AbstractGreen hydrogen (H2) production from solar water splitting necessitates photoelectrodes with superior photoelectrochemical (PEC) activity and durability. However, surface defects and photocorrosion instability—especially at high potentials—limit PEC performance and stability. Herein, the prototypical bismuth vanadate (BiVO4) photoanode is used to demonstrate a holistic approach to improve photocurrent density and long‐term stability. In this approach, high surface‐area nanostructuring of BiVO4 is combined with barium (Ba) doping with semi‐crystalline hafnium oxide (HfO2) surface passivation and single‐atom nickel platinum (NiPt) catalysts. The introduction of Ba2+ ions into BiVO4 increases the concentration of conductive V4+ ions or the ratio of V4+ ions to oxygen vacancies, avoiding V5+ dissolution during water oxidation. The semi‐crystalline HfO2, which serves as a passivation layer, prevents BiVO4 photocorrosion by suppressing harmful chemical reactions when holes are transferred to the electrolyte. The synergistic use of isolated single‐atom and Ni‐Pt coordination improves charge transfer at the photoanode/electrolyte interface, leading to enhanced PEC kinetics and stability. As a result, a photoelectrode is demonstrated with ≈6.5 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (RHE) and continuous operation for 800 h with a negligible degradation rate. This work provides a promising approach to improve photoanodes for PEC H2 production.