Pulsed Electrolysis for High Conversion Glycerol Electrooxidation on Platinum: Tuning Product Selectivity and Electrode Longevity

Pulsed electrolysis on a nickel foam supported platinum catalyst in alkaline electrolyte is shown to achieve a conversion rate towards glycerol electro-oxidation of 346 mM h at 1.2 V vs. RHE, while providing 83% selectivity to valuable C products. Pulsed operation additionally sustained electrode longevity for > 6 h by alternating between oxidation and reducing potentials which removed adsorbed species and reduced platinum (hydr)oxide species to maintain a catalytically active platinum surface. The oxidation potential, reduction potential, and pulse durations were systematically varied and the electrocatalytic data was analyzed using random-forest regression with partial dependence plots to quantify the impact on the production of four principal products — tartronic acid, lactic acid, glyceric acid, glycolic acid. Reaction selectivity through pulsed electrolysis favoured C products, likely attributed to diffusion of partially oxidized products away from the catalyst surface under reducing conditions, preventing their further oxidation and C-C cleavage to form C/C products. Under optimal pulsed electrolysis conditions, including an oxidation potential between 1.10–1.25 V vs. RHE and a reduction potential between 0.05–0.10 V vs. RHE, a partial current of 205 mA cm toward C was achieved alongside electrode longevity.