A Co-MOF-derived flower-like CoS@S,N-doped carbon matrix for highly efficient overall water splitting

Abstract

In this study, we constructed a highly effective, low-cost, non-noble-metal-based electrocatalyst to replace Pt catalysts, with a CoS@SNC catalyst being successfully synthesized. The obtained nanocatalyst was characterized via scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, powder X-ray diffraction studies, and X-ray photoelectron spectroscopy. Herein, an initially prepared N-containing Co MOF formed flower-like particles, which were obtained via a solvothermal method; further it was used for a sulfuration process as a template to achieve an S,N (heteroatom)-doped carbon electrocatalyst with embedded CoS (CoS@SNC). The synthesized flower-like CoS@SNC electrocatalyst derived from a novel MOF showed a uniform distribution of Co, S, N, and C at the molecular level in the MOF and it was rich in active sites, facilitating enhanced electrocatalytic performance. During the HER and OER in 0.1 M KOH solution, to reach a current density of 10 mA cm⁻², lower overpotentials of −65 mV and 265 mV, respectively, were required and Tafel slopes of 47 mV dec⁻¹ and 59.8 mV dec⁻¹, respectively, were seen. In addition, due to a synergistic effect between CoS and the S,N-doped carbon matrix, long-term durability and stability were obtained. This facile synthetic strategy, which is also environmentally favorable, produces a promising bifunctional electrocatalyst.