Kinetic Regulation of Cobalt Redox Cycles in a Ligand‐Assembled Co‐HAB Cocatalyst for Enhanced Solar Water Oxidation

ABSTRACT This study demonstrates a strategic advance in photoanode design by leveraging ligand engineering to unlock the full potential of 2D metal–organic frameworks (2D MOFs). We report a modified 2D MOF, Co‐HAB(VOAc), by integrating VO(acac) ₂ into the matrix of Co ₃ (hexaaminobenzene) ₂ (Co‐HAB). This molecular modification endows the Co‐HAB(VOAc)/BiVO ₄ (BVO) photoanode with superior performance, attributable to enhanced charge separation and optimized oxygen evolution reaction (OER) kinetics. The key innovation lies in the electronic fine‐tuning of the Co active sites by VO(acac) ₂ , which facilitates a rapid redox cycle of Co species, thereby efficiently driving the OER. By further coupling with an F‐NiFeOOH cocatalyst, the final photoanode delivers an outstanding photocurrent density of 6.23 mA cm ⁻² at 1.23 V _RHE and an ABPE of 2.52% at 0.52 V _RHE . This work underscores the potential of ligand‐mediated electronic regulation in MOFs for developing high‐performance photoanodes.