Impact of high-pressure torsion on hydrogen production from photodegradation of polypropylene plastic wastes.

Plastic waste entering the environment through landfilling or improper disposal poses substantial risks to ecosystems and human health. Photoreforming is emerging as a clean photocatalytic technology that degrades plastic waste to organic compounds while simultaneously producing hydrogen fuel. This study introduces high-pressure torsion (HPT), a severe plastic deformation (SPD) method, as an innovative technique to enhance the photoreforming of polypropylene (PP) plastic mixed with a brookite TiO 2 photocatalyst. Hydrogen production systematically increases with the number of HPT turns, accompanied by the formation of valuable small organic molecules. The enhancement in photocatalytic activity is attributed to strain-induced defect formation in both catalysts and plastics, as well as the creation of catalyst/plastic interphases that enhance charge carrier transport between inorganic and organic phases. These findings reveal a new functional application for SPD in energy conversion and sustainability. • High-pressure torsion (HPT) is used for the photodegradation of polypropylene plastic wastes. • Brookite TiO 2 is employed as a photocatalyst for the photodegradation. • Hydrogen production from plastic degradation increased with HPT processing. • This increase is due to strain-induced defects and catalyst/plastic interphase formation. [ABSTRACT FROM AUTHOR]