Heterointerface manipulation in the architecture of Co-Mo2C@NC boosts water electrolysis

Highly dispersed Co/Mo2C hybrid nanoparticles anchored on N-doped carbon frameworks were fabricated via a simple pyrolysis strategy. High conductivity, large surface area, and optimized electronic structure endow the catalyst with an improved HER/OER activity, and high stability. [Display omitted] Heterostructures with tunable electronic properties have shown great potential in water electrolysis for the replacement of current benchmark precious metals. However, constructing heterostructures with sufficient interfaces to strengthen the synergistic effect of multiple species still remains a challenge due to phase separation. Herein, an efficient electrocatalyst composed of a nanosized cobalt/Mo2C heterostructure anchored on N−doped carbon (Co−Mo2C@NC) was achieved by in situ topotactic phase transformation. With the merits of high conductivity, hierarchical pores, and strong electronic interaction between Co and Mo2C, the Co−Mo2C@5NC−4 catalyst shows excellent activity with a low overpotential for the hydrogen evolution reaction (HER, 89 mV@10 mA cm−2 in alkaline medium; 143 mV@10 mA cm−2 in acidic medium) and oxygen evolution reaction (OER, 356 mV@10 mA cm−2 in alkaline medium), as well as high stability. Furthermore, this catalyst in an electrolyzer shows efficient activity for overall water splitting and long−term durability. Theoretical calculations reveal the optimized adsorption−desorption behaviour of hydrogen intermediates on the generated cobalt layered hydroxide (Co LDH)/Mo2C interfaces, resulting in boosting alkaline water electrolysis. This work proposes a new interface−engineering perspective for the construction of high−activity heterostructures for electrochemical conversion.