Optimization of green hydrogen evolution from low-density plastics using TiO₂-based nano-photocatalysts with techno-economic and carbon footprint assessment

A novel approach to photo-reforming polyethylene terephthalate (PET) plastic waste was investigated to produce hydrogen (H₂) utilizing high-performing nanocomposite & atom-nanocomposite catalysts. Our study illustrates that optimizing the catalyst structure via the modified synthesis method can enhance light absorption and charge separation under neutral pH conditions. Similarly, efficient H₂ production can be achieved by optimizing PET pretreatment and reaction parameters via a cost-effective and eco-friendly pathway. Various photocatalysts were synthesized, including Au/TiO₂, Pt/TiO₂, and Zn/TiO₂. The Pt/TiO₂ atom-nanocomposite demonstrated the highest efficiency for photo-reforming PET, and H₂ production correlated with the Pt percentages in the catalyst. The study further investigated the effect of PET pretreatment under different reaction temperatures, reaction times, and concentrations. The techno-economic and carbon footprint assessment revealed that the cost of H₂ production under optimum treatment conditions was $2.19/kg of H₂, the lowest reported value under an alkaline system of H₂ generation using plastic with negative CO₂ emission.