▎ 摘　　要

In this work, nitrogen-doped graphene foam was synthesized by using hydrothermal routes. In the first step, graphene was synthesized by utilizing a modified Hummer's method and nitrogen-doped graphene foam was then synthesized at 180 degrees C by using an ammonia and graphene solution for 12 h. X-ray photon spectroscopy (XPS) was applied to determine the extent of doping by nitrogen on the graphene foam; three N-peaks were observed at 398.25, 399.69, and 401.46 eV, and XPS also showed that 6 at% of the synthesized graphene foam consisted of nitrogen atoms. The capability of this foam to absorb hydrogen was evaluated in a 6 M KOH solution through electrochemical impedance spectroscopy (EIS), galvanostatic charge/discharge, and cyclic voltammetry (CV) analysis. The hydrogen storage capacity of the achieved N-doped GF, showing the value of 1916.5 mAh.g(-1) significantly improved in comparison to that of pure graphene in previous work, due to the increasing electronegative sites at the surface of the graphene foam.(c) 2022 Elsevier B.V. All rights reserved.