Enhanced Electrochemical Behavior of Peanut-Shell Activated Carbon/Molybdenum Oxide/Molybdenum Carbide Ternary...

Biomass-waste activated carbon/molybdenum oxide/molybdenum carbide ternary composites are prepared using a facile in-situ pyrolysis process in argon ambient with varying mass ratios of ammonium molybdate tetrahydrate to porous peanut shell activated carbon (PAC). The formation of MoO₂ and Mo₂C nanostructures embedded in the porous carbon framework is confirmed by extensive structural characterization and elemental mapping analysis. The best composite when used as electrodes in a symmetric supercapacitor (PAC/MoO₂/Mo₂C-1//PAC/MoO₂/Mo₂C-1) exhibited a good cell capacitance of 115 F g^-1 with an associated high specific energy of 51.8 W h kg^-1, as well as a specific power of 0.9 kW kg^-1 at a cell voltage of 1.8 V at 1 A g^-1. Increasing the specific current to 20 A g^-1 still showcased a device capable of delivering up to 30 W h kg^-1 specific energy and 18 kW kg^-1 of specific power. Additionally, with a great cycling stability, a 99.8% coulombic efficiency and capacitance retention of ~83% were recorded for over 25,000 galvanostatic charge-discharge cycles at 10 A g^-1. The voltage holding test after a 160 h floating time resulted in increase of the specific capacitance from 74.7 to 90 F g^-1 at 10 A g^-1 for this storage device. The remarkable electrochemical performance is based on the synergistic effect of metal oxide/metal carbide (MoO₂/Mo₂C) with the interconnected porous carbon. The PAC/MoO₂/Mo₂C ternary composites highlight promising Mo-based electrode materials suitable for high-performance energy storage. Explicitly, this work also demonstrates a simple and sustainable approach to enhance the electrochemical performance of porous carbon materials.