Controllable Electron Distribution Reconstruction of Spinel NiCo₂O₄ Boosting Glycerol Oxidation at Elevated Current Density

Electrocatalytic glycerol oxidation reaction (GOR) is an effective way to convert biomass byproduct to high value-added chemicals, which; however, suffers from the low oxidation activity and conversion ratio of the presently available catalysts. Herein, the NiCo₂O₄/NF bimetallic oxide nanoarray is controllably fabricated by Ni substituting for octahedral Co³⁺ in Co₃O₄, which exhibits excellent GOR catalytic activity at elevated current densities (E₃₀₀ = 1.42 V, E₆₀₀ = 1.62 V) and overall Faradaic efficiency of 97.5% at 1.42 V (FE_{formic acid} = 89.9% and FE_{glycolic acid} = 7.62%). The high performance is attributed to the structure evolution including the rapid generation of Ni^III-OOH and Co^III-OOH active species, the optimized intermediates adsorption, and the accelerated electron transfer owing to the Ni introduction, which are evidenced by the operando spectroscopy measurements and density functional theory calculations, respectively. The GOR/hydrogen evolution coupled two-electrode electrolytic cell voltage is ≈299 mV lower than that of the water splitting at 50 mA cm⁻². More importantly, compared to conventional water splitting, this electrolyzer is stable for over 200 h at 1.75 V, reducing energy consumption by 16.9% and obtaining high value-added products at the anode concurrently.