Electronic interaction of highly-dispersed Pd with defect-rich nickel disulfide nanoarrays for selective ethylene glycol-to-glycolate electroconversion

Abstract

 Palladium (Pd) is regarded as one of the most active catalysts for electrochemical ethylene glycol oxidation (EGOR) to value-added glycolate, but its large-scale application is still restricted by limited catalytic effectiveness and exorbitant cost. Herein, we design and synthesize the defect-rich nickel sulfide nanosheet arrays on nickel foam (Ni_3-xCo_xS₂@NF) as the self-supported substrate to anchor well-dispersive Pd nanoparticles (Pd-Ni_3-xCo_xS₂@NF) with its loading as low as ca. 3.03 wt.%, which is conducive to the exposure and utilization of the active Pd sites. The optimal Pd-Ni_3-xCo_xS₂@NF electrocatalyst (1 cm² working area) could achieve an efficient EGOR performance, showing a current density of 100 mA cm⁻² at 0.77 V vs. RHE, and 98.1% faradic efficiency of glycolate. Furthermore, the in-situ Raman spectra reveal that the interaction between Pd and Ni_3-xCo_xS₂@NF significantly increasing the adsorption of EG, and Ni_3-xCo_xS₂@NF enhances the *OH adsorption capacity, thus further improve the EGOR activity and stability. This study provides an effective paradigm for enhancing the utilization and electrocatalytic performance of noble metallic catalysts, and also offers a deep insight into the interaction between the active sites and substrate.