Effect of Nitrogen and Sulfur Co-Doped Graphene on the Electrochemical Hydrogen Storage Performance of Co0.9Cu0.1Si Alloy

Co0.9Cu0.1Si alloy was prepared by mechanical alloying method. Nitrogen-doped graphene (NG) and nitrogen–sulfur co-doped graphene (NSG) were prepared by hydrothermal method. 5 wt% graphene oxide, NG and NSG were doped into Co0.9Cu0.1Si alloy, respectively, by ball milling to improve the electrochemical hydrogen storage performance of the composite material. X-ray diffraction and scanning electron microscopy were used to characterize the structure and morphology of the composite material, and the LAND battery test system and three-electrode battery system were used to test the electrochemical performance of the composite material. The composite material showed better discharge capacity and better cycle stability than the pristine alloy. In addition, in order to study the optimal ratio of NSG, 3%, 5%, 7% and 10% of NSG were doped into Co0.9Cu0.1Si alloy, respectively. Co0.9Cu0.1Si alloy doped with 5% NSG had the best performance among all the samples. The best discharge capacity was 580.1 mAh/g, and its highest capacity retention rate was 64.1%. The improvement in electrochemical hydrogen storage performance can be attributed to two aspects. On the one hand, the electrocatalytic performance of graphene is improved by co-doping nitrogen and sulfur, on the other hand, graphene has excellent electrical conductivity.