Hydrogen evolution using alloyed AuPd/TiO2 hollow spheres by photoreforming of polyethylene terephthalate waste

Abstract

Hydrogen evolution from water using solar energy is a sustainable approach but is limited by the slow kinetics of the oxygen evolution reaction. In this study, hydrogen evolution is performed using a polyethylene terephthalate (PET)-containing electrolyte, where the oxidation of ethylene glycol, one of the monomers from PET, can substitute the oxidation evolution reaction from water. AuPd alloys on high specific surface area TiO₂ photocatalysts are prepared by coprecipitation of Au and Pd on amorphous TiO₂ hollow spheres. The strong electronic interactions at the interface significantly enhance the catalytic performance for hydrogen evolution (1.26 mmol g⁻¹ h⁻¹), which is a 126 times increase compared to bare TiO₂ (0.01 mmol g⁻¹ h⁻¹). Calculations of the formation energy using density functional theory (DFT) suggest that the formation of the AuPdTi alloy is energetically favorable, possibly due to ion diffusion during annealing. The strong metal support interaction due to transfer of electrons at the interface between TiO₂ and the nanoalloy can enhance the separation efficiency of charge carriers. Hydrogen is produced from the reduction reaction of protons with electrons at the active AuPdTi sites, and the oxidation reaction takes place due to photogenerated holes at the spherical sites of the AuPdTi nanoalloys on TiO₂ HSs. Our findings thus suggest a pathway for designing effective alloyed photocatalysts aimed at the upcycling of PET waste.