Boosting electrocatalytic alcohol oxidation: Efficient d–π interaction with modified TEMPO and bioinspired structure

Abstract

Aminoxyl radicals electrocatalysis presents a sustainable method for oxidizing alcohols into high-value products. Nonetheless, the requirement for high doses of aminoxyl radicals diminishes product purity and economic viability. This study synthesized methylimidazole-functionalized 4-acetylamino-2,2,6,6-tetramethylpiperidine-N-oxyl derivative (MIAcNH-TEMPO) with a strongly electron-withdrawing imidazole group and combined it with bioinspired nickel-supported carbonaceous octopus tentacles for effective electrooxidation of alcohols, achieving high current density of 200 mA cm⁻², selectivity of 99%, and turnover frequency of 26,490 h⁻¹. In situ experiments and theoretical calculations indicated that the synergistic effect of Ni-3d_xz orbitals on the tentacle surface interacting with the π orbitals of MIAcNH-TEMPO creates a strong d–π interaction, which effectively facilitating the creation of a locally intermediate-enriched microenvironment, decreased the required quantity of aminoxyl radicals. Moreover, the high aqueous solubility of MIAcNH-TEMPO reduces the difficulty of separation process. Scale-up experiments conducted in a continuous flow electrolyzer showcased the potential of this strategy for practical applications.