Development of a SnNb2O6-Based Direct Z-Scheme Heterojunction: A Novel Approach for Efficient Tetracycline Photocatalytic Degradation

With ever-increasing attention toward the removal of pharmaceuticals and personal care products (PPCPs), it is highly essential to study promising approaches for this purpose. We introduced a novel Z-scheme SNO-ACO photocatalyst developed via hydrothermal precipitation for degrading tetracycline (TC-HCl) under visible light. SNO-ACO-9% achieved 93% TC-HCl removal in 30 min, with a high pseudo-first-order kinetic rate (0.064 min–1), 3.5 times faster than SNO, demonstrating exceptional efficiency and potential in environmental remediation, especially for antibiotic pollution. The photocatalyst's mechanisms involve enhanced light absorption and charge separation, which was facilitated through the addition of a strong oxidative photocatalyst, Ag2CO3, in a comparatively low amount in ratio to the parent reductive photocatalyst, SnNb2O6, without using a third agent as a charge mediator. Electron spin resonance (ESR) and scavenging experiments verified the formation of different reactive oxygen species and the Z-scheme heterojunction mechanism. This study will provide insight into using a more efficient system with heightened overall photodegradation activity in emerging contaminant removal.