Dual synergistic effects between Co and Mo2C in Co/Mo2C heterostructure for electrocatalytic overall water splitting

Abstract

Molybdenum carbide (Mo2C) has emerged as a promising electrocatalyst for water splitting because of its Pt-like electronic structure. However, unsatisfactory Hydrogen evolution reaction (HER) activity and poor Oxygen evolution reaction (OER) stability are obstacles to its practical application. Herein, we designed a strategy to improve the electrocatalytic performance of Mo2C by constructing a Co and Mo2C heterostructure supported on carbon (Co/Mo2C@C). Experimental and theoretical calculations showed the significant improvements caused by the synergistic effects between Co and Mo2C. Electrons from Co could transfer to Mo2C and accumulate on Mo. This promoted the adsorption of H2O and desorption of H, which improved the HER. In contrast, the Co could inhibit the oxidation and dissolution of Mo2C through a “self-sacrifice” effect, which significantly improved the OER stability of Mo2C. Owing to the synergetic effects between Co and Mo2C, the as-synthesized catalyst exhibited superior electrocatalytic performances in an alkaline electrolyte, and afforded low overpotentials of 98 and 254 mV at 10 mA cm−2 for catalyzing the HER and OER, respectively. Moreover, Co/Mo2C@C enabled overall water splitting at a cell voltage of 1.59 V, to achieve a current density of 10 mA cm−2 with an exceptional electrochemical stability that outperformed noble-metal catalysts.