Electrocatalytic Biomass Oxidation via Acid-Induced In Situ Surface Reconstruction of Multivalent State Coexistence in Metal Foams

Abstract

Electrocatalytic biomass conversion offers a sustainable route for producing organic chemicals, with electrode design being critical to determining reaction rate and selectivity. Herein, a prediction-synthesis-validation approach is developed to obtain electrodes for precise biomass conversion, where the coexistence of multiple metal valence states leads to excellent electrocatalytic performance due to the activated redox cycle. This promising integrated foam electrode is developed via acid-induced surface reconstruction to in situ generate highly active metal (oxy)hydroxide or oxide (MO_xH_y or MO_x) species on inert foam electrodes, facilitating the electrooxidation of 5-hydroxymethylfurfural (5-HMF) to 2,5-furandicarboxylic acid (FDCA). Taking nickel foam electrode as an example, the resulting NiO_xH_y/Ni catalyst, featuring the coexistence of multivalent states of Ni, exhibits remarkable activity and stability with a FDCA yields over 95% and a Faradaic efficiency of 99%. In situ Raman spectroscopy and theoretical analysis reveal an Ni(OH)₂/NiOOH-mediated indirect pathway, with the chemical oxidation of 5-HMF as the rate-limiting step. Furthermore, this in situ surface reconstruction approach can be extended to various metal foams (Fe, Cu, FeNi, and NiMo), offering a mild, scalable, and cost-effective method for preparing potent foam catalysts. This approach promotes a circular economy by enabling more efficient biomass conversion processes, providing a versatile and impactful tool in the field of sustainable catalysis.