Photocatalytic upcycling of bio-based microplastics under ambient conditions using nanostructured titania-based catalysts

The sustainable photocatalytic upcycling of plastic waste under mild conditions represents an emerging pathway toward a circular materials economy. In this study, we present the development of innovative nanostructured titania-based photocatalysts, designed to efficiently drive polymer conversion under low-intensity UVA or visible light. The catalysts consist of mixed titanium hydroxide/titanium dioxide phases, synthesized by energy-efficient sono-chemical methods. These routes yield zero- and one-dimensional nanostructure, such as doped anatase core, shell systems embedded in amorphous carbon-rich matrices or titanate nanotubes, featuring superior light-harvesting capacity, improved charge carrier separation, and enhanced surface reactivity.

The catalytic performance of these tailored materials is demonstrated in the selective photo-depolymerization of bio-based polymers, including polylactic acid (PLA), polyethylene furanoate (PEF), and polybutylene succinate (PBS), under ambient conditions. Remarkably, the process proceeds in the absence of organic solvents, additives, or sacrificial agents, affording value-added monomers and lactic acid-derived products through a fully green transformation route. Systematic optimization of process parameters ensures both activity and selectivity, emphasizing scalability and environmental compatibility.

This work establishes heterogeneous photocatalysis as a viable and sustainable strategy for ambient-condition plastic upcycling. Using PLA as a model substrate, it provides a foundation for implementing low-energy photocatalytic technologies in real-world waste valorization applications, bridging materials design with circular economy principles.

Acknowledgements

This project is carried out within the framework of the National Recovery and Resilience Plan Greece 2.0, funded by the European Union – NextGenerationEU (Implementation body: HFRI, Project “Green and Sustainable Photochemical Upcycling of Plastic Waste and Biobased Polymers to High-Added Value Chemicals" No.: 015949).