Photoelectrochemical Ethylene Glycol Oxidization Coupled with Hydrogen Generation Using Metal Oxide Photoelectrodes

Photoelectrochemical (PEC) water splitting represents a promising approach for harnessing solar energy and transforming it into storable hydrogen. However, the complicated 4-electron transfer process of water oxidation reaction imposes kinetic limitations on the overall efficiency. Herein, we proposed a strategy by substituting water oxidation with the oxidation of ethylene glycol (EG), which is a hydrolysis byproduct of polyethylene terephthalate (PET) plastic waste. To achieve this, we developed and synthesized BiVO₄/NiCo-LDH photoanodes capable of achieving a high Faradaic efficiency (FE) exceeding 85 % for the oxidation of EG to formate in a strongly alkaline environment. The reaction mechanism was further elucidated using in situ FTIR spectroscopy. Additionally, we successfully constructed an unassisted PEC device for EG oxidation and hydrogen generation by pairing the translucent Mo : BiVO₄/NiCo-LDH photoanode with a state-of-the-art Cu₂O photocathode, resulting in an approximate photocurrent density of 2.3 mA/cm². Our research not only offers a PEC pathway for converting PET plastics into valuable chemicals but also enables simultaneous hydrogen production.