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

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.