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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.
Li et al. (Thu,) studied this question.