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A sol-gel method was employed for the synthesis of new High-entropy boride (HEB) powders, (Hf 0.2 Nb 0.2 Cr 0.2 Ta 0.2 Mo 0.2)B 2 , with nanoscale. The as-synthesized powders were obtained at a relatively low temperature of 1650 °C, and had small average particle size of 62.09 nm. X-ray diffraction confirmed that the (Hf 0.2 Nb 0.2 Cr 0.2 Ta 0.2 Mo 0.2)B 2 powders were hexagonal single-phase without any oxide impurities. In particular, electrochemical performance of the (Hf 0.2 Nb 0.2 Cr 0.2 Ta 0.2 Mo 0.2)B 2 powders with multiphase and high-entropy single phase were investigated using a three-electrode system. The improved electrochemical performance of the HEB powders is realized, with 27% higher in specific capacitance compared to the powders with multiphase. The HEB powders electrode exhibits a high capacitance retention of 97.03% after 5000 cycles. [ABSTRACT FROM AUTHOR]

Abstract Bimetallic carbides with high activity and stability are promising potential materials for energy-storage application. However, the researches about Fe 2 MoC as electrode material on supercapacitors are comparatively weak, and the processing methods of Fe 2 MoC were also relatively few. Herein, a simple hydrothermal method, combining with carbothermic treatment at 900 °C, is explored to fabricate molybdenum iron carbon (Fe 2 MoC) successfully. Chitosan is not only a carbon source, but also a chelating agent to form bimetallic carbide rather than two separated monometallic carbide during the high-temperature treatment. Fe 2 MoC nanoparticles possessing large specific surface, high activity, stability and small resistance were the promising candidate for electrode material. Systematic electrochemical characterizations have verified the Fe 2 MoC (chitosan as carbon source) possesses a specific capacitance (97.7 F/g at a current density of 0.5 A/g), high rate capability (97.0% capacitance retention from 0.5 to 10 A/g) and cycling stability (83.9% capacitance retention after 1000 cycles) in 1 M KOH. In addition, it offers the energy density of 6.74 Wh/kg at a power density of 21 kW/kg. In view of the low-cost and excellent performance, Fe 2 MoC will hold great promise in energy-storage field for supercapacitors. [ABSTRACT FROM AUTHOR]