Carbon nitride frameworks padded with graphene as efficient metal-free catalyst for HER in acidic and alkali electrolytes

Although hydrogen evolution reaction (HER) is one of the most promising pathways to generate hydrogen in large-scale for future fuels, it is still lacking efficient and low-cost electrocatalysts. Here, carbon nitride frameworks padded with graphene (CNF-G) are explored as efficient metal-free catalysts with low-cost and good durability via a directly annealing commercial melamine sponge with graphene oxide. Owing to the high electrical conductivity of graphene, CNF-G exhibits outstanding catalytic activity during HER process in wide pH ranges. The overpotentials and Tafel slopes of CNF-G were 149 mV and 116 mV dec(-1) in 0.5 M H2SO4, as well as 319 mV and 160 mV dec(-1) in 1 M KOH, respectively. More importantly, CNF-G shows a high and stable catalytic activity demonstrated by a multiple cyclic voltammetry and long potentiostatic polarization.