Tailoring selectivity of electrocatalytic glucose oxidation on (Ni)Au catalysts through the surface state control

The electrochemical glucose oxidation reaction (GOR) has recently attracted much attention as part of the global effort to produce high-value-added chemicals from biomass with particular emphasis on gluconic and glucaric acids. By combining electrochemical measurements with operando Fourier transform infrared spectroscopy (FTIRS), online differential electrochemical mass spectrometry (DEMS), high-performance liquid chromatography (HPLC), and density functional theory (DFT) calculations, in this work we propose a revised mechanism of the GOR on Au and demonstrate the key role of the electrode surface composition in the distribution of the GOR products across the potential range. It appears that OH adsorbed on Au facilitates C–C bond cleavage, resulting in a decrease in glucose-to-gluconic acid selectivity above ∼0.5 V vs RHE. In contrast, the much stronger OH adsorption on Ni increases the activation barrier for C–C bond cleavage, thereby improving the selectivity of bimetallic gold-nickel nanoparticles with Au-enriched surface compared to monometallic gold. Furthermore, Ni catalyzes oxidation of hydrogen adsorbates resulting from glucose adsorption on Au sites, thus preventing anodic H$_2$ evolution.