DFT computation of quantum capacitance of transition-metals and vacancy doped Sc2CF2 MXene for supercapacitor applications

Abstract

MXenes are potential electrode materials in supercapacitors. However, the theoretical investigation of the quantum capacitance (CQ) for transitional-metal (TM) doped MXenes is scarce, and the types of electrode are unclear because of TM doping. Herein, CQ and surface storage charge (Q) of 13 kinds of 3d, 4d, and 5d TM atoms and vacancy doped Sc2CF2, named as TM@PS and VS, are investigated theoretically. The doping of 3d TM atoms can effectively modulate the magnetism of pristine Sc2CF2. CQ and Q of Sc2CF2-based electrode materials are effectively improved and the type of electrode materials is changed because of TM doping. For aqueous and ionic/organic systems, Mn@PS is an excellent anode material, while PS, VS, and Y@PS are more suitable for cathode materials of asymmetric supercapacitors. V@PS, Zr@PS, Nb@PS, Hf@PS, and Ta@PS are more suitable for anode materials in ionic/organic system. Fe@PS is a suitable electrode material of symmetric supercapacitors with high CQ and Q in aqueous system, but a cathode material of asymmetric supercapacitors in ionic/organic system. The results can provide useful information to design and develop the high-performance electrode materials.