Size-miniaturization of TiO2-ZrO2 coupled semiconductors to develop highly efficient visible- driven photocatalysts for the degradation of drugs in wastewater

Solar photocatalysis has emerged as a cost-effective and efficient approach to address water remediation challenges. Nonetheless, there is a pressing requirement to innovate and design novel photocatalysts capable of utilizing solar or visible light. In this study, morphology control and surface sensitization techniques were integrated to engineer titania-based photocatalysts that operate efficiently under blue LED light. This is accomplished through the synthesis of TiaZrbOc materials (TiXZrY) with finely tuned nano-scale dimensions, employing meticulous control through the reversed two-emulsion technique. This innovative approach has yielded remarkable performance in the removal of pharmaceutical contaminants. Zr contents highly affect the size and, thus, the active surface of the photocatalysts. XRD results indicate that a low Zr content zirconium titanates are formed whereas at high Zr contents zirconia cubic phase is the main crystalline structure detected. The heterojunction created between the zirconium titanate and the titania anatase phases can be responsible of the band gap reduction observed (Eg = 2.8 eV). A SMX degradation percent as high as 80.1 % with a decrease of the treated water toxicity was obtained for Ti70Zr30 under blue-LEDs irradiation which is explained based on the formation of zirconium titanates observed by XRD and XPS and the high active surface area.