Titania Nanopores as Photoelectrocatalysts for Coupling Hydrogen Production with Plastic Reformation

Photoelectrochemical (PEC) water splitting offers a sustainable pathway for solar-to-chemical energy conversion, yet its efficiency is often limited by sluggish water oxidation and the generation of low-value oxygen. Here, the use of engineered titania nanopore (TNP) films is reported, fabricated via anodization and thermal annealing, as co-catalyst-free photoanodes for coupling hydrogen evolution reaction (HER) with polyethylene terephthalate (PET) reformation into high-value formate. By tuning the crystallographic phase of TiO₂ from amorphous to anatase and rutile, the optimized anatase-phase electrode exhibits excellent PEC performance in a two-electrode configuration, achieving a high steady-state photocurrent density of [2.34 ± 0.67] mA cm^-2, a hydrogen evolution output of 1771 ± 30 µL cm^-2, a formate yield of 1.68 ± 0.05 mmol L^-1, and a Faradaic efficiency of 85 ± 9.0%. Notably, despite the absence of noble metals or complex heterostructures, the PEC performance of the TNP films is comparable to, or even surpasses, that of reported systems employing additional co-catalysts. This study establishes a simple and scalable PEC platform for simultaneous green hydrogen production and plastic waste valorization, offering new opportunities for sustainable energy and environmental technologies.