Asymmetric B-coordination stimulated high-spin cobalt boosts ORR

As affordable electrocatalysts for oxygen reduction reactions (ORR) in metal-air batteries, nitrogen-carbon supported atomically dispersed single-atom transition-metal electrocatalysts are emerging. Accurately modulating the first-shell coordination of single-atom metal sites remains challenging, which impedes the elucidation of geometric/electronic structures for optimizing ORR catalysts. Aiming to tackle this challenge by rational design and constructing an asymmetric coordination model catalyst Co-B/N-C, herein we unravel that asymmetric B-coordination stimulates the generation of Co high spin state (t_2g5e_g2). By using X-ray absorption spectroscopy (XAS), we confirm Co active sites are atomically dispersed with a first-shell coordination of boron and nitrogen atom (Co-B₁N₃). Thus, the adsorption strength and electron transfer between the cobalt centers and the reactants/intermediates were boosted for optimal ORR capacity (<i>E</i>_1/2 = 0.87 V). Our work will provide valuable new perspectives on the strategic development of high-performance magnetic metal catalysts for ORR.