Fabrication of La-CoMoO4@RGO composite for asymmetric supercapacitor device applications

A simple hydrothermal method has been developed for the fabrication of lanthanum-doped cobalt molybdate and its nanocomposite with reduced graphene oxide (La-CoMoO₄@RGO). A hierarchical porous La-CoMoO₄ ultrafine nanoparticle aggregated into the graphene layer was observed in scanning electron microscopic (SEM) analysis. The electrochemical performance of the synthesised electrodes was assessed through cyclic voltammetry (CV) in a three-electrode setup using a 1 M H₂SO₄ electrolyte. A superior specific capacitance was observed in La–CoMoO₄@RGO (659 F g⁻¹) compared to La-CoMoO₄ (385 F g⁻¹), RGO (311 F g⁻¹) and CoMoO₄ (140 F g⁻¹) pristine materials. In chronopotentiometric studies, La–CoMoO₄@RGO exhibited the longest discharge duration, resulting in improved superior specific capacitance, whereas CoMoO₄ exhibited the shortest discharge duration. The stability of La–CoMoO₄@RGO was found to be good and maintained 92% of its initial capacitance. An asymmetric supercapacitor (ASC) device was fabricated using La–CoMoO₄@RGO and activated carbon as positive and negative electrodes, respectively, in 1 M H₂SO₄. In ASC the peak specific capacitance achieved was 380 F g⁻¹ at a 2 mV s⁻¹ scan rate and found to decline subsequently to 78 F g⁻¹ at 100 mV s⁻¹. The exceptional electrochemical performance of the La–CoMoO₄@RGO composite could be attributed to synergism and structural composition, enhanced conductivity and the presence of significant redox-active sites. The fabricated metal-doped metal molybdate-anchored RGO nanocomposite could gain attention in further research towards other redox-based electrochemical energy remediation.