Metallic 1T phase molybdenum disulfide (MoS2) is among the most promising electrode materials for supercapacitors, but its capacitance and cyclability remain to be improved to meet the constantly increasing energy storage needs in portable electronics. In this study, we present a strategy, covalent functionalization, which achieves the improvement of capacitance of metallic 1T phase MoS2. Covalently functionalized by the modifier 4-bromobenzenediazonium tetrafluoroborate, the metallic MoS2 membrane exhibits increased interlayer spacing, slightly curled layered architecture, enhanced charge transfer, and improved adsorption capabilities toward electrolyte molecules and ions. Thanks to these boosted properties, the functionalized metallic MoS2 membrane exhibited excellent supercapacitor performances in a 0.5 M TBABF4 (acetonitrile as the solvent) electrolyte (with a specific capacitance of 135.67 F/cm3 at 1 A/g, more than three times that of the unfunctionalized metallic MoS2 membrane) and good stability, which can maintain a capacitance retention of 76.0% after 10 000 charge-discharge cycles.
Keywords: covalent functionalization; high adsorption capacitance; membrane; metallic 1T phase MoS2; supercapacitors.