3D Bimetallic Platinum-Nickel Electrodes for Electro-Oxidation of Glycerol at Ambient Conditions

Abstract

Partial electro-oxidation using renewable electricity offers a sustainable route for valorizing glycerol, a major by-product of biofuel production. This study introduces a bimetallic electrode with nanostructured platinum dendrites on nickel foam (Pt/NiF), achieving a peak geometric current density of 235 mA cm⁻² and a Pt-mass normalized current density of 3.71 ${\mathrm{A}\mathrm{mg}}_{\mathrm{Pt}}^{-1}$ for glycerol electro-oxidation at 0.92 V versus a reversible hydrogen electrode (RHE) in 3 m KOH electrolyte containing 1 m glycerol, outperforming most previously reported Pt-containing catalysts. The Pt/NiF electrode demonstrates over 92% cumulative selectivity toward C₃ products, with 64% selectivity for lactic acid at 0.65 V versus RHE over 5 h of testing. This research also highlights the role of chemical oxidation pathways (isomerization and rearrangements) in converting glycerol to lactic acid. After 5 h at 0.65 V versus RHE, the Pt/NiF electrode maintains 35% of its initial current density, plateauing at 12.2 mA cm⁻² (0.15 ${\mathrm{A}\mathrm{mg}}_{\mathrm{Pt}}^{-1}$), with performance loss likely due to surface poisoning by carbon-based reaction intermediates/byproducts or passivating platinum (hydr)oxide species. These findings pave the way for developing low-platinum group metal catalysts with high glycerol oxidation affinity and highlight the importance of considering chemical transformations during catalyst evaluation and reactor design.