Enhanced electrochemical performance of MoP2-based supercapacitor electrodes through doping with transition, post-transition, and rare earth metals

Abstract

The increasing global energy demand necessitates the development of reliable and environmentally sustainable energy storage solutions. This study explores the enhancement of molybdenum diphosphide (MoP₂)-based supercapacitor electrodes through doping with tantalum (Ta), tin (Sn), and lanthanum (La), respectively. The dopants Ta, Sn and La have been chosen from transition metals, post-transition metals and rare earth elements respectively to have the comparison of electrochemical performance. A facile hydrothermal synthesis route was employed to achieve controlled nanostructure growth, and the materials were thoroughly characterized using XRD, SEM, EDX, and TEM. Electrochemical properties were investigated through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) in a 2 M KOH electrolyte solution. The doping process significantly optimized the morphology of MoP₂, forming high-surface-area nanostructures such as nanorods, nanosheets, and nanoflowers. Electrochemical analysis revealed enhanced redox activity in the doped samples. Specifically, La-doped MoP₂ achieved superior performance of maximum capacitance of 1816F/g at 5 mV/s scan rate, with excellent cycling stability, retaining 92 % of its capacitance after 5000 cycles at 1 A/g. EIS results confirmed the high conductivity and improved charge transfer resistance of the La-doped sample. These findings highlight the critical role of rare earth element doping in optimizing MoP₂-based electrodes for supercapacitors, outperforming transition and post-transition metal doping in terms of energy storage capabilities and stability. The La-doped MoP₂ robust nanomaterial demonstrates significant potential for next-generation energy storage applications.