Engineering Oxygen Intermediates Adsorption on Amorphous NiFe Alloys for Highly Active and Selective Electrochemical Biomass Conversion.

Electrochemical 5-hydroxymethylfurfural (HMF) oxidation reaction (HMFOR) offers a promising route to transform biomass into value-added chemicals. However, the competing oxygen evolution reaction (OER) greatly limits the HMFOR selectivity. Herein, we report a facile doping strategy to engineer oxygen intermediates adsorption on amorphous NiFe alloys to boost highly selective electrochemical HMF oxidation to produce 2,5-furandicarboxylic acid (FDCA), among which, amorphous Mn-doped NiFeB alloy displays a low HMFOR onset potential of 1.35 V vs. RHE, achieving 100 % HMF conversion with 88 % FDCA selectivity at an applied potential of 1.4 V vs. RHE, outperforming amorphous NiFeB (73 % FDCA selectivity) and Mo-doped NiFeB (65 % FDCA selectivity) alloys. Experimental characterizations suggest that the introduction of Mn/Mo into amorphous NiFeB alloy can increase/decrease its electronic density and thus strengthen/weaken oxygen intermediates adsorption. Operando experiments indicate that the amorphous Mn-doped NiFeB alloy can significantly reduce the onset potential to form active Ni species, which spontaneously react with HMF via nucleophile dehydrogenation to form FDCA. Furthermore, in situ infrared spectroscopy measurements verify that the HMF oxidation pathway follows the 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) route rather than the 2,5-diformyfuran (DFF) route.