The development of carbonaceous materials electro-catalytically active for water splitting reactions could overcome multiple disadvantages of metallic catalysts, including high cost, low selectivity, poor durability, and susceptibility to evolved gas. General guidelines to design carbon-based hydrogen evolution reaction (HER) electrocatalysts still remain a topic of debate. Here, we identify single-/few-layer graphene flakes with defective edges (SLG/FLG-DE), produced by hydrogen peroxide-assisted cosolvent liquid phase exfoliation, as durable and efficient HER electrocatalysts. The SLG/FLG-DE display overpotentials at 10 mA cm(-2) of 55 and 85 mV in 0.5 M H2SO4 and 1 M KOH solutions, respectively, as well as a durable HER activity over 200 h.
