EDL Supercapacitor Electrode Performance Analysis of Group-VIB and Group-X Transition Metal Adsorbed and Doped Graphene: A Density Functional Theory Based Comparative Investigation

For the first time, the work presents a comprehensive comparative study of different Group-VIB (Cr, Mo, W) and Group-X (Ni, Pd, Pt) transition metal (TM) adsorbed and doped two-dimensional (2D) graphene (Gr) electrodes for electric double layer (EDL) supercapacitor applications using a density functional theory (DFT) based theoretical approach. The work systematically analyzes the stability of adsorption/formation, structural–electronic property correlation, excess charge density ( Q exc ), and quantum capacitance ( C Q ) variations with local electrode potential. Next, over a standard range of EDL capacitance ( C EDL ), the total interfacial capacitance ( C T ) variation with respect to C EDL is analyzed, and the performance of TM adsorbed/doped Gr is extensively benchmarked against pristine Gr. The results indicate that the TM adsorption and doping on Gr are potential material engineering techniques for improving the C Q and thereby C T . Specifically, the present work demonstrates that Cr and Mo adsorption and doping are relatively most stable in nature, which further ensures symmetric anode/cathode operation with a large C Q owing to the introduction of large density of states (DOS) near the Fermi level ( E F ). In essence, the work offers detailed theoretical insight on TM adsorption and doping in Gr for systematic electrode performance optimization for high-performance EDL supercapacitor design.