Substrate molecule adsorption energy: An activity descriptor for electrochemical oxidation of 5-Hydroxymethylfurfural (HMF)

Electrochemical oxidation of alcohol and aldehyde to carboxylic acids is one of the most important classes of catalytic reaction. The key point for such reactions lies in the fine tailoring the catalysts to improve the reaction and energy efficiency. For such a destination, identifying descriptors which are highly related to the catalytic efficiency is a prerequisite for designing electrocatalysts. In this work, taking 5-hydroxymethylfurfural (HMF), a biomass derived platform molecule containing alcohol and aldehyde, as the main research object, we revealed for the first time that the adsorption energy of substrate molecule is an activity descriptor for electrochemical alcohol and aldehyde oxidation. Too weak substrate adsorption is not favorable to C–H/O–H bond activation and dissociation, while too strong substrate adsorption hinders the formation of enough OHads (an important intermediate) due to the competitive adsorption of substrate molecules and OH– at limited reaction sites. The optimal catalytic activity can be achieved by adjusting the adsorption energy of substrate molecules to make them properly adsorbed on the catalyst surface. This work not only offers a guideline for the design of advanced catalysts towards the electrochemical alcohol and aldehyde oxidation (e.g., methanol, ethanol, benzyl alcohol, glycerol, glucose, furfural and HMF) for the utilization and production of renewable resources, but also benefits the design of other electrochemical catalysts.