Researching Borohydride Oxidation on Nickel Catalysts via Synergistic Heteroatom and Strain Engineering at the Core-Shell Interface

Direct borohydride fuel cells (DBFCs) are attractive for high-energy-density power conversion, but anode performance is limited by a trade-off between activity for borohydride oxidation (BOR) and selectivity against hydrogen evolution (HER). Overcoming this trade-off requires precise control of interfacial structure and electronic configuration. Here we present a Ni@Ni-P-N core-shell catalyst synthesized through stepwise electrodeposition, integrating P/N heteroatom incorporation with interfacial strain engineering. P/N codoping and core-shell lattice mismatch induce tensile strain in the Ni shell, shifting the Ni d-band center to lower the activation barrier for BOR while raising that for HER, thereby enhancing both activity and selectivity. Structural and spectroscopic characterization confirms a strained core-shell interface with abundant accessible active sites, increased ECSA and improved charge transfer. In three-electrode tests the catalyst attains 97.5% fuel utilization for BOR; in a DBFC single cell it delivers a peak power density of 606 mW cm⁻² and an open-circuit voltage of 1.87 V at 298 K. This work links interfacial strain to selective electro-oxidation and offers a generalizable strategy for designing advanced electrocatalysts.