▎ 摘　　要

A powerful, low-cost niobium oxide -niobium carbide-graphene oxide (NbO2/NbC/rGO) hybrid electrocatalyst is prepared by refluxing, hydrothermal method, followed by annealing process at the optimum temperature of 1050 degrees C for all vanadium redox flow battery (VRFB) application. The NbO2/NbC/rGO electrocatalyst shows the best electrochemical activity with the highest peak current densities and the lowest peak differences toward VO2+/VO2+ and V2+/V3+ redox reactions from the cyclic voltammetry compared to other samples. The rate performance of VRFB cell using NbO2/NbC/rGO modified graphite felts (NbO2/NbC/rGO/GF) shows the voltage efficiencies of 89.3%, 81.7%, 71.0%, and 59.3% by the charge-discharge current densities of 40 mA cm(-2), 80 mA cm(-2), 120 mA cm(-2), and 160 mA cm(-2), respectively, which these performances are superior to those using the pretreated GFs and the untreated GF. The charge-discharge stability test of the VRFB cell using NbO2/NbC/ rGO/GF demonstrates no significant decay after 100 cycles by the current density of 80 mA cm(-2). This observation is due to the synergistic effects related to the presence of excess oxygen vacancies on NbO2/NbC, the high content of oxygen functional groups, and the high electrical conductivity characteristics of the graphene sheet.