Electronic coupling induced high performance of N, S-codoped graphene supported CoS2 nanoparticles for catalytic reduction and evolution of oxygen

A simple synthetic method is developed for the synthesis of CoS 2 /N, S-codoped graphene. The result shows the existence of a strong electronic coupling between CoS 2 and N, S-codoped graphene. The pyrrolic and pyridinic type nitrogen and S in the form of C-S-C in N, S-codoped graphene are found to be the anchoring sites of the CoS 2 nanoparticles . As a bifunctional catalyst , the CoS 2 /N, S-codoped graphene exhibits an oxygen reduction onset potential of 0.963 V vs. RHE and delivers an oxygen evolution overpotential of 393 mV at the current density of 10 mA cm −2 . Its oxygen reduction and evolution catalytic activities are comparable to those of the Pt/C and the state-of-art RuO 2 /C, respectively. Most impressively, the CoS 2 /N, S-codoped graphene exhibits a potential gap of 771 mV. This value is lower than those of most bifuntional catalysts reported, clearly indicating its potential use as the bifunctional catalyst to replace the noble-metal based catalysts for practical applications. Additionally, our results also suggest a great importance to prepare a single pure phase CoS 2 in improving the catalytic bifunctionality of the CoS 2 /N, S-codoped graphene. The primary Zn-air battery with CoS 2 /N, S-codoped graphene shows a higher discharge peak power density than that with Pt/C.