Electrochemical aspects of sol-gel synthesized MgCoO2 for aqueous supercapacitor and alkaline HER electrocatalyst applications

We report here the cost-effective synthesis of Magnesium Cobalt Oxide (MgCoO₂) sample by the sol-gel synthesis route labeled as MCO - 3. In presence of aqueous 1 M Lithium Sulphate (Li₂SO₄) electrolyte, we obtained a capacitance of 56 F/g, an energy density of 38 Wh/kg and a capacitance retention of 92.53 % (at 5 A/g) after undergoing 1000 charge-discharge cycles. For the aqueous 1 M Sodium Perchlorate (NaClO₄) electrolyte system, we found the capacitance, energy density and capacitance retention of 47 F/g, 31 Wh/kg and 91.41% (at 3.5 A/g for 1000 charge-discharge cycles), respectively. These results establish MgCoO₂ as suitable electrode material in aqueous lithium-ion and sodium-ion supercapacitor devices. Further, MCO - 3 in the presence of aqueous 1 M Potassium Hydroxide (KOH) electrolyte showed an overpotential of 400 mV and a Tafel slope of 174 mV/dec, making it a suitable candidate for alkaline Hydrogen Evolution Reaction (HER) electrocatalyst.