Selective Electrooxidation of Ethylene Glycol to Formate with Hydrogen Cogeneration in Ni₃S₂ Nanodomains on NiFeMn-LDH Nanosheet Arrays

The electrocatalytic oxidation of small organic molecules, such as ethylene glycol (EG), can be paired with the hydrogen evolution reaction (HER) to effectively lower the overall cell voltage, thereby enhancing energy efficiency for hydrogen production. Moreover, the anodic EG oxidation reaction (EGOR) can generate valuable C1 and C2 compounds, offering a sustainable approach to greener chemical production. The industrial viability of this process requires nonprecious metal electrocatalysts that demonstrate high performance at low potential and exhibit high selectivity. In this study, we report on a cost-effective electrocatalyst based on a nickel sulfide phase (Ni3S2) heterogeneously nucleated on the surface of nickel–iron-manganese layered double hydroxide (NiFeMn-LDH) nanosheet arrays and supported on nickel foam (NF), demonstrating exceptional activity for the coupled HER and EGOR in alkaline conditions. This Ni3S2@NiFeMn-LDH/NF catalyst achieves an EG-to-formate faradaic efficiency of up to 90% at 1.5 V, with glycolate and oxalate as minor byproducts. Density functional theory calculations reveal that the EGOR was facilitated by the phase-separated Ni3S2, which lowers the energy barrier of the rate-limiting step. This work presents a promising, sustainable pathway for hydrogen production alongside value-added chemical generation from the electrooxidation of EG.