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

TL;DR

This paper explores how high-pressure torsion (HPT), a severe plastic deformation technique, enhances hydrogen production from polypropylene waste via photoreforming, offering a novel approach to energy and environmental sustainability.

Contribution

It introduces HPT as a new method to improve photocatalytic degradation of plastic waste, increasing hydrogen yield through defect formation and interphase creation.

Findings

Hydrogen production increases with more HPT turns.

Strain-induced defects enhance charge transport.

Formation of catalyst/plastic interphases improves activity.

Abstract

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 TiO2 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.