Work

Recent advances in photocatalytic plastic waste conversion: a review on renewable energy pathways

Year: 2025

Type: article

Abstract: The escalating global crisis of plastic waste and the urgent demand for clean energy alternatives necessitate innovative, integrative solutions. Among emerging approaches, solar photoreforming stands out as a transformative dual-function technology that simultaneously degrades polymeric waste and produces hydrogen fuel. This review explores a cutting-edge strategy that synergistically integrates high-pressure torsion (HPT) a severe plastic deformation technique with defect-engineered brookite-phase titanium dioxide (TiO 2 ) nanoparticles to significantly elevate the solar-driven photoreforming performance of polypropylene (PP) waste. HPT introduces intense shear forces under compressive pressures (∼6 GPa), inducing substantial microstructural transformations in PP. These include the formation of high-density dislocations, amorphous domains, and interfacial defects, all of which enhance the polymer’s surface reactivity and its interaction with photocatalysts. Concurrently, brookite-phase TiO 2 , prized for its narrow band gap (∼3.1 eV), enhanced charge carrier separation, and high photoactivity, serves as an efficient photocatalyst. The strong interfacial coupling between the defect-rich PP surface and brookite TiO 2 nanoparticles facilitates rapid charge transfer, suppresses electron–hole recombination, and enhances radical generation. As a result, the integrated system exhibits a 2.4-fold improvement in hydrogen evolution, achieving production rates up to 580 μmol h −1 g −1 under solar irradiation. Moreover, the process enables selective oxidation of polymer fragments, yielding value-added chemicals such as formic acid and acetic acid with faradaic efficiencies exceeding 45 %. This review further elucidates the underlying mechanisms of defect-mediated catalysis, emphasizing the roles of nanoparticle phase composition, surface chemistry, and morphology. Collectively, this work establishes a promising and scalable pathway for circular plastic-to-fuel conversion, providing both environmental remediation and clean energy generation. The integration of mechanical defect engineering and nanostructured photocatalysis represents a pivotal advancement toward sustainable, high-efficiency solar photoreforming technologies.

Source: Reviews in Inorganic Chemistry

DOI: 10.1515/revic-2025-0061