Quantum capacitance of supercapacitor electrodes based on M2C MXenes with pure -O and mixed termination: A first-principles study

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2023-07, Vol.941, p.117529, Article 117529
• Main Authors: Yan, Hai-Tao, Zhang, Rui-Zhou, Li, Xiao-Hong, Cui, Hong-Ling
• Format: Article
• Language: English
• Subjects: Density functional theory; MXene; Quantum capacitance; Surface storage charge; Transitional metal
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2023.117529

•Sc2CO2, Zr2CO2 and Hf2CO2 monolayers are potential cathode materials.•M2CO2 monolayer gradually transfers from cathode to anode material with the weakening metallicity of TM atom.•The wide voltage has little influence on the electrode type of materials.•Mixed termination has changed the cathode character of Zr2CO2 and Hf2CO2 to anode character in aqueous system. MXenes have drawn great attention as potential electrode material because of the high capacitive performance. However, there are little information about the quantum capacitance (Cdiff) and surface storage charge (Q) of M2C MXene with pure -O and mixed surface termination. In this paper, density functional theory (DFT) is utilized to explore the Cdiff and Q of M2CO2 monolayers with 3d, 4d and 5d transitional metals (TM) in aqueous and ionic/organic systems. The most stable configurations for the studied systems are confirmed. Sc2CO2, Zr2CO2 and Hf2CO2 monolayers are potential cathode materials. Ti2CO2 monolayer is a potential anode material. The wide voltage has little influence on the electrode type of materials. M2CO2 monolayers gradually transfer from cathode to anode material with the weakening metallicity of transitional metal atom. M2C MXenes with mixed configuration are further explored. M2CO0.42F1.19(OH)0.39 (M = Sc, Cr, Nb, Ta) are cathode materials in aqueous system, M2CO0.42F1.19(OH)0.39 (M = Ti, V, Zr, Mo, Hf, W) are suitable for anode materials.