Enhancing the photodegradation of Metronidazole under natural sunlight using a new Co3O4/HMS semiconductor–insulator photocatalytic heterojunction

The design of new specific photocatalysts to achieve excellent photocatalytic performances in the photodegradation of organic pollutants, specially the nonbiodegraded ones, is of a crucial importance nowadays to clean the contaminated water resources aiming to solve the problem of shortage in clean water. In this work, a cobalt supported over hexagonal mesoporous silica (9%Co/HMS) catalyst was synthesized and applied in the removal of Metronidazole in aqueous solutions by photodegradation under sunlight. An unexpected excellent photocatalytic performance was obtained (97% of MNZ removal in sunny days vs. 74% in cloudy days). This excellent performance results from the creation of a semiconductor–insulator heterojunction between Co₃O₄ and the carrier HMS. Even more interesting, the removal efficiency was kept up four cycles. Therefore, this study may provide a new opportunity for the future development of high-performance heterogeneous catalysts based on mesoporous silica in aquatic environmental pollution control in either sunny or cloudy weather.