Construction of three-dimensional cobalt sulfide/multi-heteroatom co-doped porous carbon as an efficient trifunctional electrocatalyst.

Exploring cost-effective non-precious metal electrocatalysts is vital for the large-scale application of clean energy conversion devices ( i.e. , fuel cells, metal-air batteries and water electrolysers). Herein, we present the construction of a three-dimensional cobalt sulfide/multi-heteroatom co-doped carbon composite as a trifunctional electrocatalyst for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) through one-step sulfidation of zeolitic-imidazolate frameworks (ZIFs) using sulfur powder as a sulfur source. By virtue of the distinct periodic metal-nitrogen coordination structure and the abundant micropores within the ZIF precursor, sub-10 nm Co 9 S 8 nanoparticles (NPs) are homogenously anchored on a Co, S and N multi-heteroatom co-doped carbon framework with a large specific surface area that exposes sufficient reactive sites for these electrocatalytic reactions. The optimized Co 9 S 8 /CoNSC exhibits outstanding ORR, OER and HER performance, comparable or even superior to those of commercial Pt/C and RuO 2 . The small Co 9 S 8 NPs and Co-N x species embedded in the carbon matrix cooperatively catalyze the OER and ORR, while the HER catalysis is mainly contributed by Co 9 S 8 NPs. Furthermore, the Co 9 S 8 /CoNSC shows outstanding anti-poisoning capability towards sulfur species during ORR catalysis with no obvious activity degradation observed in 0.1 M KOH containing 50 μM SO 3 2- species, significantly outperforming commercial Pt/C. The assembled rechargeable Zn-air battery using the Co 9 S 8 /CoNSC as a cathode shows a high power density (150 mW cm -2 ) and the assembled water electrolyzer only requires 1.585 V at a current density of 10 mA cm -2 when using this material as an anode and a cathode. This work provides an effective strategy to design and synthesize efficient, durable and anti-poisoning cobalt chalcogenide-based trifunctional electrocatalysts for the large-scale application of clean energy conversion devices.