Defect engineered nanostructured LaFeO3 photoanodes for improved activity in solar water oxidation

Abstract

LaFeO₃ (LFO) is recognized as a candidate material for solar water oxidation, but its photoelectrochemical response remains modest and stagnant. With the aim of advancing LFO photoanodes for the oxygen evolution reaction (OER), here, a nanorod array-type electrode combined with defect and surface engineering protocols has been demonstrated, delivering a benchmark performance of 0.4 mA cm⁻² at 1.23 V vs. RHE with an onset potential below 0.55 V vs. RHE. It was found that oxygen defects activated the surface towards OER, while NiFeO_x coating suppressed surface recombination. It was discovered, however, that the performance was limited by rapid (nanosecond timescale) bulk recombination, as well as the ultrashort hole diffusion length (<5 nm). Overall, this work provides guidelines to accelerate the progress of LFO electrodes, as well as novel insights that afford a better understanding of oxide perovskite photoanodes.