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AKE: Arbeitskreis Energie

AKE 3: Poster

AKE 3.2: Poster

Dienstag, 11. März 2025, 14:00–16:00, Tent

Molybdenum-induced modifications in the quantum capacitance of graphene-based supercapacitor electrodes: A DFT study — •David Ansi, Henry Martin, Linus Labik, and Eric Abavare — Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

Electrochemical Double-layer Capacitors (EDLCs) offer high power density but low energy density due to limited surface area. Graphene, with its high theoretical surface area and capacitance, is a promising material for enhancing EDLC performance. However, the capacity of graphene is restricted by the limited density of states near the Fermi level, resulting in low quantum capacitance (C_Q). Doping is a suitable technique for enhancing graphene’s C_Q toward improved supercapacitor efficiency.

Inspired by the molybdenum cofactor, this study investigates molybdenum-induced modifications to graphene’s C_Q. Electronic structures of 15 electrode models were obtained using DFT calculations with the GGA-PBE functional and ultrasoft pseudopotentials in Quantum Espresso. Structures were optimized using the BFGS algorithm with a 3x3x1 supercell for simulations.

The study demonstrates that modifications involving Mo, N, S, and vacancy defects significantly enhance the C_Q of graphene-based supercapacitor electrodes. The highest C_Q values were observed when Mo was introduced, due to contributions from Mo’s 4dz² and 4s states. The presence of Mo may introduce pseudocapacitance. These findings highlight Mo-modified graphene as a promising material for EDLCs.

Keywords: Supercapacitor; Graphene; Quantum Capacitance; Molybdenum; Doping