Strong coordination ability of sulfur with cobalt for facilitating scale-up synthesis of Co9S8 encapsulated S, N co-doped carbon as a trifunctional electrocatalyst for oxygen reduction reaction, oxygen and hydrogen evolution reaction

High activity trifunctional non-noble electrocatalysts , targeting oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER), are rationally designed by integrating the merits of both Co 9 S 8 nanoparticles and carbons nanosheets . Herein, Co 9 S 8 loaded with S, N co-doped carbon core–shell catalyst (Co 9 S 8 @SNC) was reasonably designed and synthesized by using the strong coordination effect between Co 2+ and C S at the molecular level. The significant synergistic effect between the S, N co-doped carbon shell and Co 9 S 8 core endows the catalyst with excellent catalytic performance for ORR, HER, and OER reactions. The carbon shell enhances the conductivity of the hybrid material , while the Co 9 S 8 core provides the main catalytic active sites. More specifically, the half-wave potential for ORR is 0.846 mV, and the overpotential at 10 mA cm −2 for OER and HER are 320 mV and 170 mV, respectively. To test its practical application, zinc-air battery assembled by Co 9 S 8 @SNC shows a high power density of 239 mW cm −2 , excellent rechargeability, and long cyclic stability. This work provides a promising and extensible method to in-situ synthesize core–shell metal sulfides loaded S, N co-doped carbon composites, which can be a promising candidate for electrocatalytic material in energy storage and conversion devices.