Efficient and Ultrastable Iodide Oxidation Reaction Over Defect-Passivated Perovskite Photoanode for Unassisted Solar Fuel Production

Recently, lead halide perovskites have emerged as promising photoanode materials for efficient hydrogen production. However, the sluggish kinetics of the oxygen evolution reaction (OER) and interfacial defect-mediated charge accumulation inevitably result in efficiency loss and degradation of perovskite photoanodes. Herein, a defect-passivated electron transport layer-based perovskite photoanode combined with a catalyst layer favorable is introduced for iodide oxidation reaction bearing a small thermodynamic barrier and rapid kinetics compared to OER for efficient solar fuel generation. The resulting perovskite photoanode revealed a saturated photocurrent density of 22.4 mA cm⁻² at 0.3 V versus the reversible hydrogen electrode (V_RHE) with an impressive onset potential of −0.2 V_RHE as well as durability for 225 h in a neutral electrolyte. In addition, an unbiased hydrogen-production device comprising a perovskite photoanode and Pt coil electrocatalyst is demonstrated, achieving a remarkable solar-to-chemical conversion efficiency of 11.45% and stable operation for 25 h. Moreover, a wireless artificial leaf-structured device realizing solar-driven hydrogen generation in natural sea water under outdoor sunlight is presented.