Photocatalytic Disinfection of Waterborne Pathogens

Photocatalytic disinfection harnesses light-activated semiconductors to generate reactive species that inactivate bacteria, viruses and other waterborne microorganisms. Under ultraviolet or visible illumination, semiconductor surfaces such as titanium dioxide (TiO₂) or zinc oxide (ZnO) absorb photons and create electron–hole pairs. These charge carriers react with water and dissolved oxygen to form hydroxyl radicals, superoxide anions and hydrogen peroxide, which attack cellular membranes, proteins and nucleic acids. The method offers a chemical-free, energy-efficient route to microbial control, reducing reliance on chlorination or heat-based treatment. Advances in material engineering—doping, composite formation and surface functionalisation—have extended activity into the visible spectrum, permitting operation under solar irradiation. Reactor designs range from immobilised coatings on tiles and tubing to suspended nanoparticle systems, with pilot-scale trials demonstrating the potential for integration into rural and urban water supplies. Barriers to large-scale adoption include catalyst recovery, treatment time and mass-transfer limitations, but ongoing innovations in photocatalyst morphology and reactor engineering promise to overcome these challenges. Globally, photocatalytic disinfection addresses the burden of waterborne disease in regions with limited infrastructure, offering decentralised, low-cost treatment and supporting Sustainable Development Goals for clean water and sanitation.

Research from Nature Portfolio

Studies have revealed that iron-doped zinc oxide nanoparticles can achieve rapid solar-driven inactivation of multidrug-resistant Escherichia coli, outperforming undoped ZnO and TiO₂ catalysts. Complete bacterial disinfection was observed within 90 minutes under sunlight, with hydrogen peroxide identified as the principal oxidative species. Membrane lipid peroxidation and potassium leakage assays confirmed destabilisation of cell envelopes, and electron microscopy highlighted severe morphological damage. Importantly, the catalyst retained stability and activity in real water samples, demonstrating robust performance across diverse environmental matrices and potential for field deployment.

Photocatalytic Disinfection of Waterborne Pathogens publication trend

The graph below shows the total number of articles in photocatalytic disinfection of waterborne pathogens across all publications each year (not limited to Nature Index journals).

Technical terms

Photocatalysis: Light-driven activation of a catalyst that generates reactive species for chemical or biological transformations.

Reactive oxygen species (ROS): Highly reactive molecules (e.g. hydroxyl radicals, superoxide anions) that damage microbial biomolecules.

Semiconductor photocatalyst: A material with a defined band gap (e.g. TiO₂, ZnO) that absorbs photons to produce electron–hole pairs.

Solar-photocatalysis: Utilisation of natural sunlight to drive photocatalytic reactions for water and air disinfection.

Virus-like particles (VLPs): Non-infectious assemblies that mimic viral architecture, used to study photocatalytic inactivation mechanisms.

References

1. Why five decades of massive research on heterogeneous photocatalysis, especially on TiO2, has not yet driven to water disinfection and detoxification applications? Critical review of drawbacks and challenges. Chemical Engineering Journal (2023).
2. Light-Induced Transformation of Virus-Like Particles on TiO2. ACS Applied Materials & Interfaces (2024).
3. Understanding Mechanism of Photocatalytic Microbial Decontamination of Environmental Wastewater. Frontiers in Chemistry (2018).
4. Disinfection of Multidrug Resistant Escherichia coli by Solar-Photocatalysis using Fe-doped ZnO Nanoparticles. Scientific Reports (2017).