“…[33][34][35] Among them, metal phosphides with metal-like characteristics are promising bi-functional electrocatalysts due to their excellent electrical conductivity, high physicochemical safety and low cost. 27,[36][37][38] Cobalt phosphide, as a semiconductor material with excellent thermal stability, strong chemical stability, outstanding electrical conductivity and efficient catalytic properties, is a highly efficient, stable and inexpensive transition metal phosphide, which has the conditions for the preparation of highly efficient bi-functional electrocatalysts and has attracted much attention in recent years. 39,40 For example, Jiang et al 41 immobilized Co 2 P particles on Co, N and P co-doped graphene nanosheets, which showed excellent bi-functional electrocatalytic activity, where the electronegativity of C (2.55) was greater than that of P (2.16) and lower than that of N (3.04).…”