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

• The doping of 3d TM atoms can effectively modulate the magnetism of pristine Sc 2 CF 2 . • Mn@PS is an excellent anode material for aqueous and ionic/organic systems. • The doping of Ti, V, Cr, and Mn atoms changes the type of electrode material for aqueous systems. • PS, VS, and Y@PS are suitable for cathode materials for aqueous and ionic/organic systems. • Re@PS system is suitable for aqueous system, but not preferable for ionic/organic systems. MXenes are potential electrode materials in supercapacitors. However, the theoretical investigation of the quantum capacitance (C Q ) for transitional-metal (TM) doped MXenes is scarce, and the types of electrode are unclear because of TM doping. Herein, C Q and surface storage charge (Q) of 13 kinds of 3d, 4d, and 5d TM atoms and vacancy doped Sc 2 CF 2 , named as TM@PS and VS, are investigated theoretically. The doping of 3d TM atoms can effectively modulate the magnetism of pristine Sc 2 CF 2 . C Q and Q of Sc 2 CF 2 -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 C Q 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.