Engineering In ₂ O ₃ photocatalysts for environmental remediation: Focus on pharmaceutical contaminants

Pharmaceutical contaminants are increasingly detected in aquatic environments due to their widespread use, chemical persistence, and incomplete removal by conventional wastewater treatment processes. Photocatalysis has emerged as a promising advanced oxidation strategy for degrading these recalcitrant compounds, yet most existing reviews focus on model organic pollutants or general photocatalyst development, offering limited insight into pharmaceutical-specific behavior. This review provides a comprehensive and critical assessment of In2O3-based photocatalysts for pharmaceutical removal, emphasizing how intrinsic material properties and engineering strategies govern degradation performance. The influence of morphology, polymorphism, defect chemistry, doping, and heterojunction construction on light absorption, charge separation, and pollutant interaction is systematically analyzed. Particular attention is given to visible-light- and solar-responsive systems, including Z-scheme and S-scheme architectures, which consistently exhibit enhanced redox capability and improved degradation efficiency. By comparing performance trends across major pharmaceutical classes and identifying stability, scalability, and mechanistic limitations, this review establishes structure – activity relationships and highlights key challenges for practical implementation. The findings provide design guidelines for next-generation In2O3 photocatalysts and offer a pharmaceutical-centric framework to advance photocatalytic wastewater remediation under realistic conditions