A facile mechanochemical preparation of Co3O4@g-C3N4 for application in supercapacitors and degradation of pollutants in water.

Our study is aimed at synthesizing cobalt oxide (Co3O4) with graphite carbon nitride (g-C3N4) to form a Co3O4@g-C3N4 hybrid through a green mechanochemical one-pot synthetic approach for manufacturing efficient supercapacitor electrodes and photocatalysts. In the present study, the Co3O4@g-C3N4 hybrid revealed a significantly higher specific capacitance (Cs) (of ~ 457.2 Fg-1 at a current density of 1 Ag-1) than that of the pristine Co3O4, which proved its pseudocapacitive behavior, with a couple of redox peaks observed in three electrode measurements (obtained by using a 3.0-M KOH aqueous electrolyte). The optimized Co3O4@g-C3N4 hybrid was further embedded for a symmetric supercapacitor performance, delivering an excellent Cs of ~ 92 Fg-1 at a current density of 1 Ag-1; this was supplemented with a remarkable cycling stability (~ 92% over 5000 cycles). The Co3O4@g-C3N4 hybrid was further examined for photocatalysis activity using a rhodamine B (RhB) dye, and more than 95% RhB dye was degraded through the photocatalytic reduction process (after 60 min of UV irradiation). This Co3O4@g-C3N4 hybrid catalyst exhibited excellent reusability and stability and appears to be a highly efficient, cost-effective, eco-friendly, and reusable catalyst; the g-C3N4 present with the Co3O4 acted as a conductive nano-network, leading to a higher capacitive and photocatalytic performance.