Co3O4–C3N4 p–n nano-heterojunctions for the simultaneous degradation of a mixture of pollutants under solar irradiation

Abstract

Environmental remediation employing sunlight-active semiconductor nano-heterostructures provides effective solutions for handling emerging contaminants through a greener approach. Herein, we report the creation of ultrafine dispersions of Co₃O₄ nanoparticles in a g-C₃N₄ matrix by a simple one-pot synthetic strategy involving the co-pyrolysis of constituent raw materials. Calcination of a homogeneous mixture of melamine and cobalt nitrate at 550 °C/2 h leads to the formation of Co₃O₄–C₃N₄ p–n nano-heterojunctions that displayed extended absorption in the visible wavelength region owing to the synergistic role of Co₃O₄ particles. Moreover, the surface area values of the composites reached 90 m² g⁻¹, a tenfold increase from the value of 8 m² g⁻¹ obtained for the pristine C₃N₄. The band bending, induced by the p–n nano-heterojunctions, leads to the formation of intimate interfaces having enhanced photophysical properties. The mass normalized photoluminescence spectra of the heterojunctions indicated reduced exciton recombinations that are validated further by the enhanced sunlight-induced photocatalytic degradation of a mixture of methylene blue and tetracycline organic pollutants.