Enhanced Photoelectrochemical Water Splitting of BiVO4 Photoanode via Synergistic Effects of Polycarbazole Hole Transport Layer and NiFeOOH Cocatalyst

Solar-driven photoelectrochemical hydrogen production is a promising way to achieve carbon neutrality, but severe charge recombination in photoanodes limits the conversion efficiency. Herein, the conjugated polycarbazole framework (CPF-TCB) as the hole transport layer and NiFeOOH as the oxygen evolution cocatalyst are combined to simultaneously enhance the efficiency of charge separation and surface catalytic kinetics in BiVO4 photoanodes. CPF-TCB provides an appropriate energy level for rapid hole extraction while suppressing recombination, whereas NiFeOOH markedly increases the density of intermediate surface states (i-SS) to accelerate the oxygen evolution reaction. Consequently, the constructed BiVO4/CPF-TCB/NiFeOOH photoanode achieves a photocurrent density of 4.25 mA cm–2 at 1.23 VRHE and exhibits photostability for 20 h. This work provides a paradigm for exploiting the synergistic effects of organic hole transport layers and oxygen evolution cocatalysts toward efficient and durable solar-driven hydrogen production.