P-block boron-bridging strategy constructing hollow spherical Fe-B-Ni diatomic catalyst with trifunctional activity...

Rechargeable zinc-air batteries (ZABs) require efficient electrocatalysts to boost the sluggish oxygen reduction reaction (ORR)/ oxygen evolution reaction (OER) kinetics at the air cathode. However, designing high-activity catalysts faces considerable challenges due to spatial and electronic constraints. Herein, a boron-doped hollow spherical porous carbon (HS-FeNi-BNC) anchored with Fe-B-Ni diatomic sites is prepared via a facile B-bridging strategy, realizing the regulated construction of heteroatom doping and diatomic active sites. HS-FeNi-BNC possesses abundant micropores/mesopores, uniformly dispersed FeNi diatomic centers (0.27 nm spacing) with a Fe-B-Ni bridge structure, and topological carbon defects induced by B/N co-doping. HS-FeNi-BNC exhibits exceptional trifunctional electrocatalytic performance in alkaline electrolytes, with an ORR E_1/2 of 0.864 V, an OER overpotential of 308 mV and a hydrogen evolution reaction (HER) overpotential of 301 mV at 10 mA cm^-2. HS-FeNi-BNC-based ZABs achieve an outstanding wide-temperature operating range of -10 °C to 60 °C, a specific capacity of 761.51 mAh g^-1 and a Zn utilization efficiency of 92.9%, outperforming Pt/C + RuO₂-based ZABs. Density functional theory (DFT) calculations reveal that the Fe-B-Ni bridge structure triggers p-d orbital hybridization, regulating metal site electronic structures, optimizing reaction intermediate adsorption and accelerating interfacial electron transfer. This work advances the development of high-efficiency heteroatom-modified non-noble metal multifunctional catalysts.