Bias-free, high-rate solar hydrogen production in alkaline media with a NiCo-coupled perovskite photocathode

Abstract

Photoelectrochemical (PEC) water splitting provides a sustainable route for hydrogen production from solar energy. In this work, we demonstrate a bias-free PEC cell integrating a perovskite photocathode with a bifunctional NiCo electrocatalyst and pairing it with a NiCo-coated Ni foam anode. To minimize anodic overpotential, the oxygen evolution reaction (OER) is replaced with the hydrazine oxidation reaction (HzOR, E° = −0.33 V_RHE), enabling efficient operation under alkaline conditions. This architecture achieves a photocurrent density of −24 mA cm⁻² with a photovoltage of 0.99 V under AM 1.5G illumination, among the highest reported for a bias-free PEC cell. Beyond solar-to-hydrogen conversion, this system simultaneously detoxifies hydrazine, establishing a dual-functional platform for sustainable fuel production and environmental remediation. These findings highlight the practical potential of integrating high-performance perovskite photoelectrodes with alternative anodic reactions to overcome efficiency and stability barriers in solar-to-hydrogen conversion.