Dopant Engineering for Modulating Charge Carrier Separation Dynamics and Persistent Organic Pollutant Degradation: A Review

Dopant engineering has become a central strategy for addressing the fundamental shortcomings of pristine semiconductor photocatalysts, such as limited visible-light absorption and rapid charge carrier recombination. This review presents a detailed analysis of recent advances in atomic-scale dopant engineering for modulating the charge separation dynamics to degrade persistent organic pollutants (POPs). Different electronic and structural mechanisms governing transition metal, noble metal, rare-earth element, non-metal and multi-element co-doping strategies are deconstructed. The ways foreign atoms modulate the semiconductor framework are critically evaluated. Bandgap narrowing via orbital hybridization, shallow vs. deep trap-assisted kinetic separation and generation of localized internal electric fields via lattice distortion are the physical pathways discussed. This work also correlates the atomic modifications with macro-scale photocatalytic performance in terms of the degradation pathways for synthetic azo dyes, complex pharmaceuticals and broad-spectrum antibiotics. Finally, this work addresses prevailing industrial bottlenecks such as the over-doping dilemma, structural stability and scalability presenting a definitive roadmap to design the next generation of highly efficient solar driven photocatalysts for global environmental remediation.