▎ 摘　　要

Heteroatom-doped graphene as highly efficient metal-free electrocatalyst is emerging as the most promising alternative to Pt-based electrocatalysts for hydrogen evolution reaction (HER). However, developing heteroatom-doped graphene with competitive HER activity remains a great challenge. Here, we reported an effective strategy to employ plasma etching method to create more topological defects on S-doped graphene, and obtained plasma-etched, S-doped graphene exhibited a significantly enhanced HER activity with an overpotential of 178 mV at a current density of 10 mA cm(-2). It was proved that the synergetic coupling between S-doping and plasma-induced topological defects contributed to the excellent HER performance. We further showed that the combination of high S-doping level with thiophene-S-rich species and appropriate amount of topological defects could maximize the HER activity. The successful combination of plasma-assisted defect engineering and heteroatom-doping in this work may open up a new pathway for developing highly efficient graphene-based metal-free catalysts toward HER. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.