Role of Mo doping and the interfacial interaction mechanism of Ni-Mo-S electrodes: experimental and computational study.

Abstract

The metal element doping strategy is often used to optimize the electrode materials of supercapacitors as they can provide rich redox active sites and high conductivity; however, the synergistic effect between different metallic ions and the interfacial interaction mechanism during the energy storage process are still unclear. In this work, Mo-doped Ni-Mo-S (NMS) nanoflowers are prepared by one-step electrodeposition, and the ratios of Ni : Mo are tailored. Dynamics analysis shows that the Mo element occupies a prominent position in the capacitive behavior contribution. Meanwhile, density functional theory (DFT) reveals that Mo doping influences the electronic structure of the NMS materials and their affinity towards OH- in the electrolyte. All the electrodes (NMS-0, NMS-0.5, NMS-1, NMS-2, NMS-3, and NMS-4) exhibit excellent specific capacitance (1640.8, 1665.8, 1456.2, 1414.6, 1515.4 and 1214.6 F g-1, respectively) and good cycling stability (80.8%, 84.5%, 75.4%, 78.2%, 93.1% and 99.6%, respectively) for 5000 cycles. This work proposes an efficient method to synthesize NMS materials and theoretically studies the effect of the Mo element during the energy storage process.