Built-in Electric Field in Hollow FeOOH/CoOOH Heterostructure: Enhanced *OH Adsorption and C-C Bond Cleavage Towards Efficient Ethylene Glycol-to-Formate Conversion

The exploration of sustainable approaches for plastic waste disposal has emerged as an urgent imperative task. This research presents an innovative and eco-friendly electrochemical route to degrade plastic waste, ethylene glycol (EG), into value-added formate. To this end, an interesting hollow FeOOH/CoOOH heterostructure is successfully fabricated for EG oxidation. The difference in work functions between FeOOH and CoOOH results in the establishment of a built-in electric field (BEF), which is beneficial for the adsorption of EG and *OH. As a result, the FeOOH/CoOOH demonstrates outstanding catalytic performance in the EG oxidation reaction (EGOR) with an exceptionally low potential of only 1.32   V at 10   mA   cm -2 and a high Faraday efficiency of 92.19% for formate generation. Glycollic acid is identified as a pivotal intermediate in the EGOR by in-situ infrared spectroscopy. Theoretical computations disclose that the FeOOH/CoOOH heterostructure not only causes an upward shift of the d-band center but also largely enhances the *OH adsorption, thus speeding up the cleavage of the inert C-C bond and markedly facilitating the conversion of EG to formate. This research not only enriches the fundamental comprehension of the EGOR but also provides deep insights for the rational design of highly selective and active EGOR catalysts.