Zinc oxide-based photocatalysts for wastewater remediation: recent advances and perspectives

Zinc oxide (ZnO) is a cost-effective, non-toxic semiconductor with strong potential for photocatalytic degradation of persistent pollutants in wastewater. However, its wide bandgap (~3.37 eV) and rapid electron–hole recombination limit efficiency under solar light. This mini review summarizes the fundamentals of ZnO photocatalysis, identifies intrinsic limitations, and discusses recent advances in doping, heterojunction engineering, and green synthesis. Modified ZnO systems now demonstrate enhanced visible-light absorption, improved charge separation, and recyclability, with applications in dye, pharmaceutical, and heavy metal removal. Future work should address scalability, real wastewater testing, and sustainability assessment to bridge laboratory success with practical deployment.