Boosting oxygen reduction durability by embedding Co₉S₈ nanoparticles into Co single atoms anchored porous carbon...

Developing an efficient and low-cost oxygen reduction electrocatalyst is essential for the application of aqueous zinc-air batteries (ZABs). Herein, we report a facile adsorption-confined pyrolysis strategy to fabricate the hybrid electrocatalyst (denoted as Co₉S₈/Co_SA-PC) by embedding Co₉S₈ nanoparticles into Co single atoms (Co-SAs) anchored porous carbon sheets for boosting oxygen reduction reaction (ORR) durability. In this strategy, the Co²⁺ ions are first absorbed into oxygen-rich porous carbon nanosheets and further form the Co-SAs with the help of thiourea in the following pyrolysis procedure, which is believed to be able to confine the generated Co₉S₈ nanoparticles into carbon frameworks due to their interface interaction. Benefiting from the synergistic effect of different components, the obtained Co₉S₈/Co_SA-PC electrocatalyst for ORR exhibits outstanding catalytic activity with a half-wave potential of 0.82 V and a distinguished long-term durability with a current retention of 80 % after cycling 80 h under alkaline conditions, which is superior to commercial Pt/C. Moreover, the assembled ZABs with Co₉S₈/Co_SA-PC as cathodic catalyst deliver a high specific capacity of 764 mAh g_Zn^-1 at 10 mA cm^-2 and the outstanding peak power density of up to 221.4 mW cm^-2. This work provides a novel structure design strategy to prepare transition metal sulfide-based electrocatalysts with superior durability for ORR.