Abstract
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.
Highlights
IntroductionTheir study revealed that the O/S dual-modified nanoporous carbon (OSC) electrode delivered a specific capacitance of 168 F g−1 , 3.5 times higher than the pristine nanoporous carbon in 6 M KOH aqueous electrolyte due to the introduction of the oxygen functional groups on the surface of nanoporous carbon [19]
A ternary peanut shell activated carbon/molybdenum oxide/molybdenum carbide (PAC/MoO2 /Mo2 C) composite was successfully synthesized via a facile in-situ pyrolysis route of ratio of porous carbon to different mass loading of ammonium molybdate
Mo2 C nanostructures into the porous carbon based on the X-ray diffraction (XRD), Raman, HRTEM, searea electron diffraction (SAED), energy operating dispersiveatX-ray (EDX) mapping and X-ray photoelectron spectroscopy (XPS) analysis
Summary
Their study revealed that the OSC electrode delivered a specific capacitance of 168 F g−1 , 3.5 times higher than the pristine nanoporous carbon in 6 M KOH aqueous electrolyte due to the introduction of the oxygen functional groups on the surface of nanoporous carbon [19] Another promising method is the heteroatom-doping (nitrogen, sulphur, phosphorous, boron and so on) of a porous AC matrix, which enhances the capability to store charge in the material. The obtained ternary composites portrayed interesting merits based on the existing incorporated nanostructures of the MoO2 -Mo2 C within the nanoporous PAC-based material including: (i) high specific surface area with hierarchically porous structure of the PAC, (ii) pseudocapacitive effect by the redox reaction of MoO2 and (iii) superior electrical conductivity and stability of the Mo2 C. Our study demonstrates a simple and sustainable approach to enhance the electrochemical performance of porous carbon materials
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