Electro-oxidation of biomass derived species, such as glycerol and glucose, presents a sustainable approach for converting side streams into value-added products. Additionally, employing electro-oxidation of biomass offers an attractive alternative to the challenging oxygen evolution reaction in an anodic compartment. Electro-oxidation activity and selectivity depend on an electrocatalyst, but also on the electrode potential, the pH, and the electrolyte. For example, for broadly employed gold (Au) electrocatalysts, electro-oxidation activity of glycerol and glucose have been observed under alkaline conditions, whereas under acidic and neutral conditions, Au is almost inactive.

The characteristic of solid-liquid interface a play pivotal role in electrocatalysis. These interface properties can vary substantially depending e.g. on solvent and electrode potential and the variations can, in turn, have direct impact on electrocatalytic behaviour. The grand-canonical ensemble (GCE) DFT calculations  [1]  offer a robust framework for modelling electrochemical interfaces and reactions at the atomic level, while maintaining fixed electrode potentials but they are computationally more costly than standard canonical DFT calculations and not always possible for complex organic molecules.

Under electrocatalytic conditions, solvent-originating species may be present on the surface of the electrocatalyst, potentially influencing the electro-oxidation of biomass-derived organic compounds. To assess the presence or absence of species such as hydroxyls and oxygens, Pourbaix diagrams can be computed [2,3]  across varying electrocatalytic conditions. Our findings reveal that under oxidating potentials, the Au(111) surface contains OH groups at basic conditions, while no OH species are present at acidic conditions [2]  In contrast, on the Pt(111) surface [3], the Pourbaix diagrams are substantially more complex, highlighting the rich pattern of mixed O and OH overlayer structures at alkaline conditions.

In my presentation, I will also discuss how we employed DFT methods to analyse reaction mechanisms and energetics glycerol [2]  and glucose [4] electro-oxidation on Au(111) at varying electrocatalytic reaction conditions. The presence or absence of adsorbed OH groups significantly impact on electro-oxidation of organic species on Au(111), with alkaline conditions being energetically more favourable  giving an explantions for  the experimentally observed pH-dependent activity and selectivity under alkaline conditions.

Overall our results emphasize the importance of considering the electrocatalytic reaction conditions in calculations, as these conditions can have a substantial impact the reaction mechanism, thermodynamics, and kinetics, thus affecting the overall performance of the electrocatalyst.