Hydrogen-etched CoS 2 to produce a Co 9 S 8 @CoS 2 heterostructure electrocatalyst for highly efficient oxygen evolution reaction.

There is a pressing requirement for developing high-efficiency non-noble metal electrocatalysts in oxygen evolution reactions (OER), where transition metal sulfides are considered to be promising electrocatalysts for the OER in alkaline medium. Herein, we report the outstanding OER performance of Co 9 S 8 @CoS 2 heterojunctions synthesized by hydrogen etched CoS 2 , where the optimized heterojunction shows a low η 50 of 396 mV and a small Tafel slope of 181.61 mV dec -1 . The excellent electrocatalytic performance of this heterostructure is attributed to the interface electronic effect. Importantly, the post-stage characterization results indicate that the Co 9 S 8 @CoS 2 heterostructure exhibits a dynamic reconfiguration during the OER with the formation of CoOOH in situ , and thus exhibits a superior electrocatalytic performance.