▎ 摘　　要

Fuel cells applying natural biomass as energy resources are considered to be one type of potential device to substitute traditional energy output of consuming fossil fuels. The practical use of such a device depends on the development of active electrocatalyts preferring to be made of nonprecious elements. Herein, we report a copper nanocomposite with copper nanoparticles and copper(II) ions immobilized on nitrogen-doped graphene, synthesized from a simple pyrolysis approach. The nanocomposite exhibits efficient electrocatalytic capability for glucose oxidation reaction in alkaline electrolytes, and the copper(II) ions are determined as the main active sites. It is shown that the electron density of copper(II) ions, which is tuned by a moderate electron-donating effect from neighboring copper nanoparticles and nitrogen dopants of graphene, might be a general descriptor of electrocatalytic activity.