Ag–NiO Heterojunction with Synergistic Adsorption of Aldehyde/OH^– Groups for Target Electrooxidation

The activation of a specific functional group of organic molecules holds fundamental importance toward the reaction pathway but remains a great challenge. In this work, a class of heterostructures made of Ag nanoparticles and NiO nanowires on nickel foam (Ag–NiO/NF) realizes precise electrooxidation of aldehyde groups, i.e., 5-hydroxymethylfurfural (HMF), furfural, formaldehyde, etc. It exhibits an ultralow potential of 0.45 V vs RHE (reversible hydrogen electrode) at a current density of 10 mA cm–2 for conversion of HMF to 5-hydroxymethyl-2-furanoic acid (HMFCA). The performance surpasses most state-of-the-art electrocatalysts. Moreover, the yield of product reaches 99% with a selectivity of 99% and a Faraday efficiency of 100%. In situ experimental evidence and theoretical calculation reveal that the heterostructure enhances the capture of aldehyde and OH– species, promoting the coupling of intermediates to deliver outstanding activity. This work presents a rational pathway for the preparation of electrocatalysts toward accurate transformation of biomass into useful organics.