Biomass-Derived Porous Graphitic Carbon with Excellent Electrocatalytic Performances for Vanadium Redox Reactions

Biomass-derived carbon materials have attracted more and more attention in energy storage field owing to their diversity, low price and environmental friendliness. In this paper, porous graphitic carbon derived from biomass was obtained as bifunctional electrocatalyst for vanadium redox reaction by hydrothermal treatment for scaphium scaphigerum and following FeCl3 treatment. FeCl3 activated electrocatalyst (BDC-Fe) is characterized by nanoscale, large specific surface area (615.6 m2 g−1), and high graphitization degree. Compared with hydrothermal carbon (BDC-H) and hydrothermal/carbonized carbon (BDC-C), BDC-Fe demonstrates superior electrocatalytic performance for V2+/V3+ and VO2+/VO2+ redox reactions. The introduction of BDC-Fe can accelerate the charge transfer and mass transfer processes for electrode reaction, which can effectively reduce the electrochemical polarization of electrode reaction. The energy storage performance was evaluated by charge-discharge tests. The cell using BDC-Fe shows excellent electrochemical performance. At 100 mA cm−2, the discharge capacity and energy efficiency of the cell using BDC-Fe are 81.82 mA h and 67.5%, respectively, 21.8 mA h and 4.5% higher than those of pristine cell. Our study reveals that low-cost, porous, and graphitic carbon from biomass by FeCl3 activation as bifunctional electrocatalyst demonstrates a promising prospect in vanadium redox flow battery.