▎ 摘　　要

A metal-free highly torn amine functionalized nitrogen doped graphene (HT-AFNG) used as hydrogen evolution reaction (HER) catalyst is prepared by using a simple synthesis method involving the hydro-thermal reaction of graphene oxide in the presence of ammonia and the subsequent ball milling. The metal-free HT-AFNG is efficient for the HER in the acid solution and can deliver an onset potential of 100 mV and an overpotential of 350 mV at the current density of 10 mA cm(-2), which is much lower than those of the singly and dually doped graphene reported previously. The amine functionalized and nitrogen doped structure plays an important role in the high catalytic activity of the HT-AFNG, where the amine group can greatly reduce the vertical bar Delta G(H*)vertical bar value at both defect and edge sites as well as increases the electron transfer capability of nitrogen dope graphene (NG). Significantly, the highly torn structure also makes a big contribution on the high catalytic activity of the HT-AFNG, since it allows for the good accessibility of the active sites for the HER. The strategy involves the introduction of electron donating groups open a new research pathway towards the improvement of HER catalytic activity of graphene-based materials. (C) 2018 Elsevier Ltd. All rights reserved.