Room-temperature solid state synthesis of Co₃O₄/ZnO p–n heterostructure and its photocatalytic activity

A facile solid state reaction route was employed to synthesize the Co₃O₄/ZnO p-n heterostructure by grinding zinc acetate, Co₃O₄ and sodium hydroxide with appropriate molar ratios together at room temperature without any surfactant or template. The as-obtained samples were characterized for the surface structure, chemical state, phase structure using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), photoluminescence spectroscopy (PL), Brunauer–Emmett–Teller (BET) analysis. The photodegradation of Rhodamine B (RhB) dye clearly revealed that the photocatalytic activity of the prepared Co₃O₄/ZnO p-n heterostructure was higher than that of pure ZnO nanostructure and 7% Co₃O₄ loaded Co₃O₄/ZnO photocatalyst exhibited the maximum photocatalytic activity. Under UV light it was also found to be more than five times that of pure ZnO. The photoluminescence (PL) emission spectroscopy confirmed the high separation efficiency of the photogenerated electrons-holes in the Co₃O₄/ZnO heterostructure which led to the high photocatalytic activity of the material.