Magnetic catalysts offer a way to enhance the slow kinetics of spin-selective oxygen precipitation reactions (OERs) through the spin-magnetic effect. However, the spin-magnetic effect, i.e., the correlation between intrinsic magnetism and catalytic activity, is not fully understood. Here, we modulate the saturation magnetization strength (Ms) of NiCo2-xFexO4 through an iron doping strategy and evaluate the magnetic field-assisted OER performance accordingly. The experimental results reveal a clear positive correlation between the Ms value and the magnetic field-enhanced OER activity. The ferromagnetically coupled NiCo1.6Fe0.4O4 has the largest Ms value of 8.6 emu/g and exhibits the strongest spin-magnetization effect, with a 14.6% decrease in overpotential and a 31.5% decrease in Tafel slope upon application of a magnetic field. Density Functional Theory (DFT) calculations showed that the adsorption energy of *OH in the high spin cobalt active site is highly dependent on the Ms value of the ferromagnetic spinel catalyst. The increased activity is mainly attributed to the optimized eg-orbital modulation of the high-spin cobalt ions and the stronger spin coupling between the cobalt active site and the oxygen intermediate. Elucidation of the relationship between intrinsic magnetism and magnetic field-assisted OER activity provides new ideas for the design of magnetic catalysts for OER and other spin-selective reactions.
DOI: 10.1021/acscatal.5c00081.