Molybdenum Induced Modifications in the Quantum Capacitance of Graphene-Based Supercapacitor Electrodes: First-Principle Calculations
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Date
2024
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Publisher
PSS
Abstract
Herein, spin-polarized calculation is performed based on density-functional
theory in the frame of generalized gradient approximation to examine the
quantum capacitance (CQ) and surface charge storage of graphene(G)-based
supercapacitor electrodes modified with molybdenum, sulfur, nitrogen, and
monovacancy. In total, 15 electrode models, including graphitic doping,
monovacancy doping, and Mo adsorption on pristine and single-vacancy graphene
structures are analyzed. In the results, it is demonstrated that vacancy
defects and N/S/Mo doping enhances the CQ of graphene. Among all configurations,
pyrrolic-S (d1S) shows the lowest CQ performance due to few states at
the Fermi level. Electrodes with Mo adsorption exhibit the highest CQ, particularly
when Mo is adsorbed at the top site of graphene. However, formation and
adsorption energy calculations suggest that Mo is more likely to adsorb at hollow
sites. Optimally, Mo can be most effectively utilized by loading it onto vacancy or
N/S-decorated vacancy sites. The significant contribution of Mo’s 4dz2 and 4s
states to CQ, along with the charge-redistribution around the Mo complexes, may
facilitate proton-coupled electron transfer to enhance pseudocapacitance. In
these findings, valuable insights into designing high quantum capacitance of
2D materials with electroactive sites for improved energy storage are offered.
Description
This article is published by PSS 2024 and is also available at 10.1002/pssb.202400459