Halide doping and morphology engineering in bismuth-based MOFs for enhanced water oxygen evolution

Precise morphology control in metal-organic frameworks (MOFs) is crucial for optimizing photocatalytic performance in solar water splitting. We report a one-pot solvothermal strategy to engineer the morphology of bromine-doped bismuth terephthalate (BiBDC) MOFs by tuning the Br:Bi molar ratio, yielding evolution from rod-like to mace-like and flower-like architectures. The mace-like BiBDC-0.5 structure, obtained at a Br:Bi ratio of 0.5, exhibits enhanced surface area, preferential crystal orientation, and abundant exposed active sites. This unique morphology suppresses charge recombination and promotes efficient electron-hole separation, enabling a high visible light oxygen evolution rate of 15.2 μmol h^-1, outperforming undoped and heavily doped counterparts, with excellent stability over 10 h. This work demonstrates that halide doping and morphology engineering are effective strategies to optimize bismuth-based MOFs, providing a scalable, template-free route for fabricating high-performance photocatalysts for solar-driven water oxygen evolution.