Facile cost-effective fabrication of Cu@Cu2O@CuO–microalgae photocatalyst with enhanced visible light degradation of tetracycline

The widespread use and negative environmental effects of antibiotics have made their removal from aqueous media essential in terms of wastewater treatment. Accordingly, a hybrid helical [email protected]2[email protected]–microalgae photocatalyst for antibiotic photodegradation was synthesized in this study by a simple, inexpensive, and scalable process based on electroless Cu deposition and soft thermal treatment. The hybrid photocatalyst was more competitive for the photocatalytic degradation of tetracycline, especially in terms of mineralization and energy consumption, than state-of-the-art photocatalysts. The excellent photocatalytic performance is attributable to the effective formation of onion-like [email protected]2[email protected] heterojunctions, which synergistically lower the electron–hole recombination rate, promote the utilization of light and photogeneration of charge carriers, and decrease the photocorrosion activity. All these effects result in the enhanced photocatalytic degradation and mineralization of tetracycline. The high photocatalytic performance of the [email protected]2[email protected]–microalgae hybrids under LED irradiation resulted in a significantly lower electrical energy per order—i.e., the electrical energy required to diminish the tetracycline concentration by one order of magnitude in a unit of volume—of 57 kW h m−3 order-1. Importantly, the [email protected]2[email protected]–microalgae hybrids can easily be recycled after reaching their effective lifetime to fabricate competitive microalgal pellets, then integrated into a circular process in an environment–energy nexus to minimize the generation of residues.