Construction of Interfacial Fe–O–P Linkages on Hematite via Coordination Self-Assembly to Prolong Carrier Recombination Lifetime for Solar-Driven Water Oxidation

Surface passivation is critical for mitigating detrimental surface states in photoelectrodes, yet the unsatisfactory charge transfer efficiency at the semiconductor-passivation layer interface severely limits the achievable current density. Constructing atomic-scale charge transfer channels to ensure efficient carrier extraction while preserving passivation is a Frontier in photoelectrode design but remains challenging. Here, an ultrathin (∼2 nm), conformal, amorphous iron–nickel–phytate complex (PA–FeNi) layer was engineered on an Fe2O3 surface via interfacial coordination assembly, establishing Fe–O–P bond linkages to optimize interfacial carrier transport. The atomic-level integration saturated the surface dangling bonds on Fe2O3 to mitigate recombination losses and created efficient charge-transfer pathways, promoting photogenerated hole migration to the PA–FeNi layer. Furthermore, the PA–FeNi layer as the oxygen evolution reaction (OER) cocatalyst significantly reduced the energy barrier of the rate-determining *OH → *O step. These synergistic effects extend the average lifetime of photogenerated holes from 1.5 to 297.7 ps, a value far exceeding those reported previously for photocatalytic and photoelectrochemical systems. As expected, the optimized Fe2O3@PA–FeNi photoanode delivers a notable photocurrent density of 3.29 mA cm–2 at 1.23 VRHE, exhibiting a 3.05-fold enhancement over pristine Fe2O3, while maintaining 99.8% of its initial performance after 24 h durability test. Importantly, the PA–metal complex strategy demonstrates universal applicability, substantially improving the performances of BiVO4, TiO2, and WO3 photoanodes through the dual optimization of interfacial charge transfer and OER kinetics. This work proposes a facile, versatile, and cost-efficient interfacial engineering paradigm for designing an ideal photoelectrode/cocatalyst interface that synergistically regulates charge kinetics and catalytic activity in solar energy conversion systems.