Bifunctional Pd–Al:SrTiO3 Photocatalyst Sheet for m2-Scale Waste PET Photoreforming and Feasibility Study

Photocatalytic reforming of waste plastics offers a route towards a circular plastics economy and sustainable energy generation by producing commodity chemicals and green H2 while mitigating plastics accumulation in the environment. As a monomer of polyethylene terephthalate (PET), a dominant waste plastic, ethylene glycol (EG) has gained attention as a promising substrate for reforming processes, but photocatalytic EG oxidation suffers from low product selectivity, slow reaction rates, and poor stability due to the limited availability of efficient oxidation cocatalysts. Here, a bifunctional Pd catalyst is introduced to simultaneously drive EG oxidation and H2 evolution on an Al-doped SrTiO3 (Al:SrTiO3) semiconductor. The Pd-loaded Al:SrTiO3 system was coated onto glass substrates to fabricate scalable photocatalytic sheets, enabling a 1 m2-scale outdoor demonstration of waste PET bottle reforming. In three days of continuous operation under natural sunlight, 48, 45, 19 and 3 mmol m−2 of H2, formate, glycolate and glycolaldehyde dimer, respectively, were produced. A comprehensive feasibility study was performed based on this prototype waste PET reforming system to identify key areas to prioritise in future research. Although photocatalytic reforming was unsurprisingly found to be premature for practical application, reactor cost and photocatalyst stability were identified as critical issues to address to realise a feasible large-scale system. This work delivers a systematic feasibility assessment of large-scale PET reforming and establishes a foundation for developing scalable, practical photocatalytic reforming technologies.