LAUSR

The addition of oxygen evolution reaction (OER) catalysts improves photoelectrochemical (PEC) performance of photoanodes via facilitating charge transfer at the electrode/electrolyte interface and/or passivating surface hole-trap states. Yet, the poor interface and coating quality of the catalyst overlayer often plagues the performance enhancement due to the interference of hole/electron transport across the photoanode/catalyst interface. Here we address these challenges using a citrate-assisted method that allows conformal deposition of Ni–Fe hydroxide [NiFe(OH)x] overlayers on hematite nanowire photoanodes. These NiFe(OH)x overlayers significantly enhance the surface hole transfer kinetics and passivates the surface states. The NiFe(OH)x-encapsulated hematite nanowires exhibit an early turn-on potential of 0.53 V vs RHE. The findings highlight not only the importance of uniform OER catalyst coating but also the critical role of molecular linkers in boosting the performance of photoanodes.