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