Synergistic interfacial coordination and Iron-cobalt orbital coupling for high-performance photoelectrochemical water...

Despite its significant promise for photoelectrochemical (PEC) water splitting, the practical efficiency of bismuth vanadate (BiVO₄) is severely constrained by rapid bulk charge recombination and sluggish surface water oxidation kinetics. Coupling a hole transport layer (HTL) with an oxygen evolution cocatalyst (OEC) constitutes a highly effective strategy to circumvent these limitations. Herein, we report a rationally designed photoanode architecture comprising Mo-doped BiVO₄, an FeOOH HTL, and a novel urea-bridged perylene diimide polymer coordinated with Co and Fe ions (PDICF) as the OEC (denoted as Mo:BiVO₄/FeOOH/PDICF). Crucially, the interfacial synergy among these integrated layers dramatically amplifies PEC performance. The abundant O and N atoms within the PDICF matrix coordinate with Fe sites in the underlying FeOOH, establishing high-speed charge-transfer channels for efficient hole extraction. Within the PDICF framework, Co centers act as primary active sites, synergistically modulated by adjacent Fe ions. Density functional theory (DFT) simulations elucidate that strong FeCo orbital coupling facilitates rapid electron transfer and stabilizes the valence states of the active centers, thereby significantly lowering the activation energy barrier for the oxygen evolution reaction (OER). Consequently, the optimized photoanode achieves an exceptional photocurrent density of 5.6 mA cm^-2 at 1.23 V versus the reversible hydrogen electrode (RHE). Furthermore, the uniform PDICF coating effectively mitigates photocorrosion, sustaining a robust current density of 5.28 mA cm^-2 with outstanding long-term durability. This study provides profound insights into synergistic interface and catalyst engineering, offering a robust paradigm for the design of highly efficient and stable PEC systems.