Cobalt Oxide Supported on Silica‐Coated Magnetite: Synthesis and Performance in the Photodegradation of Methylene Blue

Abstract

Abstract Photocatalytic degradation offers a sustainable solution for removing harmful dyes from wastewater, but the development of efficient and reusable catalysts remains a challenge. Cobalt oxide supported on silica‐coated magnetite was synthesized and its performance as a photocatalyst for methylene blue degradation without a sacrificial agent was investigated. Cobalt oxide (Co 3 O 4 /SiO 2 @Fe 3 O 4 ) was produced by the calcination of cobalt complex/SiO 2 @Fe 3 O 4 at the temperature of 550 °C. The cobalt‐based photocatalysts were characterized by thermogravimetric analysis (TGA), Fourier‐transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL), diffuse reflectance ultraviolet‐visible (DRUV‐vis) spectroscopy, and Brunauer–Emmett–Teller (BET) surface area analysis. In this study, Co 3 O 4 /SiO 2 @Fe 3 O 4 was synthesized and evaluated as a photocatalyst for the degradation of methylene blue (MB) under UV and visible light irradiation. The composite exhibited significant photocatalytic activity, achieving 92% dye degradation within 150 min under UV light without the use of sacrificial agents. As demonstrated by photoluminescence spectroscopy, a low electron‐hole recombination rate, which is correlated with a high content of surface oxygen vacancies and defects, is the key feature for achieving high photocatalytic activity of the cobalt oxide‐based photocatalyst.