Interface built-in electric field regulation in Co5Mn12-MOF/Ti-Fe2O3: Boosting photocarrier separation for high-efficiency photo-assisted Zn-air batteries

By doping metal Mn into the traditional OER catalyst Co-MOF, a bimetallic MOF is constructed to improve the unsatisfactory discharge performance of Co-MOF. The Co/Mn ratio is optimized to achieve the dual catalytic effect. After decorating Co 5 Mn 12 -MOF onto Ti-Fe 2 O 3 nanorods, the charge transfer resistance and recombination rate of photogenerated carriers are significantly suppressed, with the charge separation efficiency increasing from 34.2% to 67.6%. A built-in electric field is formed between the two components, through which photogenerated holes are driven to the electrolyte interface. Consequently, the photocurrent density at 1.23 V vs. RHE is enhanced by approximately 6.7 times, achieving a remarkable improvement in OER performance. The charging potential at 0.1 mA cm −2 decreases from 2.08 V under dark conditions to 1.19 V under illumination. Owing to this dual catalytic function, the round-trip energy efficiency of Co 5 Mn 12 -MOF/Ti-Fe 2 O 3 is improved to 84.9%.