Synergistic Lewis and Brønsted Acid Sites Promote OH* Formation and Enhance Formate Selectivity: Towards High‐efficiency Glycerol Valorization

Abstract

AbstractAs a sustainable valorization route, electrochemical glycerol oxidation reaction (GOR) involves in formation of key OH* and selective adsorption/cleavage of C−C(O) intermediates with multi‐step electron transfer, thus suffering from high potential and poor formate selectivity for most non‐noble‐metal‐based electrocatalysts. So, it remains challenging to understand the structure–property relationship as well as construct synergistic sites to realize high‐activity and high‐selectivity GOR. Herein, we successfully achieve dual‐high performance with low potentials and superior formate selectivity for GOR by forming synergistic Lewis and Brønsted acid sites in Ni‐alloyed Co‐based spinel. The optimized NiCo oxide solid‐acid electrocatalyst exhibits low reaction potential (1.219 V@10 mA/cm2) and high formate selectivity (94.0 %) toward GOR. In situ electrochemical impedance spectroscopy and pH‐dependence measurements show that the Lewis acid centers could accelerate OH* production, while the Brønsted acid centers are proved to facilitate high‐selectivity formation of formate. Theoretical calculations reveal that NiCo alloyed oxide shows appropriate d‐band center, thus balancing adsorption/desorption of C−O intermediates. This study provides new insights into rationally designing solid‐acid electrocatalysts for biomass electro‐upcycling.