Copper-Doped NiOOH for the Electrocatalytic Conversion of Glycerol to Formate via the Inhibition of the Oxygen Evolution Reaction

The combination of the electrocatalytic glycerol oxidation reaction (GOR) with the cathodic hydrogen evolution reaction serves to reduce the anodic overpotential, thereby facilitating the efficient production of hydrogen. However, the GOR is confined to a narrow potential range due to the competition of the oxygen evolution reaction (OER) at high potential. Therefore, it is necessary to develop a catalyst with a high Faraday efficiency of formate (FE_FA) over a wide potential range. Herein, Cu-doped NiOOH catalysts were synthesized by electrodeposition to inhibit the competing OER during the GOR process, achieving a current density of 10 mA cm^-2 at 1.278 V vs RHE, a FE_FA over 70.36% within a broad potential range of 1.3 V vs RHE to 1.6 V vs RHE, and a maximum FE_FA of 96.46% at 1.35 V vs RHE. In situ spectral studies and DFT calculations revealed that Cu doping slowed the *OH to *O step for the inhibition of the OER and enhanced glycerol adsorption to accelerate the GOR. A competitive reaction mechanism for boosting glycerol electro-oxidation to formate was proposed, presenting a feasible strategy for the highly selective production of electrocatalytic value-added chemicals and the sustainable production of hydrogen energy.