Synergistic enhancement of electrochemical storage using g-C3N4 modified MoO2/MoO3 nanostructure electrodes via thermal decomposition

A series of g-C3N4 modified MoO2/MoO3 nanocomposites were successfully synthesized in a single-step thermal decomposition technique by changing the amount of melamine from 0, 3.2, 6.3 and 12.25 g with molybdenum precursor and the synthesized nanocomposites were named as MG-0.0, MG-0.025, MG-0.05 and MG-0.075. The effect of the g-C3N4 loading on the molybdenum oxides (MoOx) was systematically studied. Intriguingly, upon the calcination processes in the presence of melamine and citric acid, part of MoO3 was reduced and formed the MoO2, which resulting the formation of g-C3N4/MoO2/MoO3 heterojunction. Among all the prepared nanocomposites, greater capacity is noticed for MG-0.075 i.e. 151.1C/g at 0.2 A/g. Moreover, a hybrid coin-cell-type asymmetric supercapacitor device (HSDs) was developed using MG-0.075 and activated carbon (AC) materials as positive and negative electrodes, respectively, which has shown high specific capacitance (165.7 F/g at 1.5 A/g), and power density (375 W/kg), energy density (51.77 Wh/kg). Comprehensive investigations, including XRD, FESEM, HRTEM, XPS, and electrochemical characterizations, were employed to reveal the morphological, structural, and compositional subtleties of these nanostructures. Surprisingly, the addition of g-C3N4 not only allowed for the development of a unique heterojunction, but it also dramatically increased electrical conductivity and charge transport efficiency, resulting in superior electrochemical storage capacities.