Facilitating Charge Transport and Utilization in Mo-BiVO4 via FeCo-Metal–Organic Framework Dual-Function Modification for Efficient Photoelectrochemical Water Splitting

The photoelectrochemical water splitting performance of BiVO4 photoanodes has historically been constrained by poor charge transport and sluggish water oxidation kinetics. Here, we design a heterojunction photoanode by coupling Mo-doped BiVO4 with a bimetallic FeCo-metal–organic framework (MOF) constructed using an extended π-conjugated linker (4,4′-biphenyldicarboxylic acid). The bimetallic FeCo-MOF based on the elongated backbone simultaneously serves as a hole-extraction layer that facilitates interfacial charge separation and an excellent oxygen evolution cocatalyst. It not only establishes an efficient charge transport channel but also plays a crucial role in improving the surface reaction kinetics. The optimized Mo-BiVO4/FeCo-MOF photoanode achieves a photocurrent density of 4.18 mA cm−2 at 1.23 V vs RHE and maintains stable operation for over 20 h, substantially outperforming pristine BiVO4. This work highlights the synergistic benefits of linker-engineered bimetallic MOF for high-performance solar water oxidation.