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 Fe 2 O 3 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 Fe 2 O 3 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 Fe 2 O 3 @PA–FeNi photoanode delivers a notable photocurrent density of 3.29 mA cm –2 at 1.23 V RHE, exhibiting a 3.05-fold enhancement over pristine Fe 2 O 3, 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 BiVO 4, TiO 2, and WO 3 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.