Solar Photocatalytic Degradation of Nanoplastics with Hydrogen Production: A Proposed Reaction Mechanism

The improper management of plastic waste, combined with its low biodegradability, enables microplastics (MPs) and nanoplastics (NPs) to enter the environment, particularly aquatic ecosystems. MPs and NPs have emerged as significant environmental pollutants, raising increasing concern due to their persistence and the challenges associated with their removal. Conventional wastewater treatment plants are often unable to completely eliminate microplastics, allowing them to persist in secondary effluents [1]. A further risk associated with MPs is the release of plastic additives, such as phthalates, into water supplies. Their widespread presence across environmental systems is particularly alarming due to their potential impacts on terrestrial and aquatic ecosystems, including the human food chain [2]. This underscores the urgent need for the removal and degradation of plastic pollutants. At the same time, global population growth and rapid industrial development are driving a dramatic rise in energy demand and fossil fuel consumption. As a result, research into renewable energy solutions has intensified. One promising strategy is the conversion of plastic waste into valuable fuels, such as hydrogen, which is gaining importance as a clean energy source and has therefore attracted significant interest. Photocatalysis is considered an effective method for degrading plastics and generating hydrogen in an environmentally friendly manner. For this reason, we developed an efficient photocatalyst for hydrogen generation using polystyrene nanoplastics (PS NPs) as a sacrificial agent under visible light. We prepared a series of visible light-responsive plasmonic photocatalysts consisting of TiO₂ nanoparticles (NPs) supporting Pd, Au, Pt and Ag NPs through the impregnation method. Among the synthesized materials, the 3 wt% Pd/TiO₂ NP photocatalyst exhibited the highest hydrogen generation capacity, producing 1329.76 μmol H₂ g cat⁻¹ after 2 hours of irradiation, while also reducing the average diameter of PS NPs. Together some experimental results this presentation propose a detailed hypothetical reaction mechanism (Figure 1) involving multiple elementary steps that are responsible for both NPs degradation and hydrogen evolution. This study demonstrates the potential of solar-driven nanoparticle photocatalysis to achieve environmental remediation and hydrogen evolution simultaneously [3].