Electrochemical Oxidation of Formic Acid on Polycrystalline Platinum Surfaces

Decreasing carbon emissions remains a global goal and is essential for the sustainability of current and future energy demands. Using electrochemical methods, formic acid can be oxidised and the energy from this reaction utilised in fuel cells which is a promising step towards carbon neutrality. However, the electrochemical conversion of formic acid is limited by the efficiency and selectivity of the electrocatalysts on which the reaction happens. Platinum has been researched extensively for this application, although it has limitations due to surface poisoning by carbon monoxide during formic acid oxidation. Here we quantify the relationship between electrochemical formic acid oxidation and the structure of platinum surfaces across a polycrystalline platinum surface comprising different crystal grains and grain boundaries. We identify distinct differences between grains and grain boundaries. The boundaries generally heighten the activity of formic acid oxidation, compared to the surrounding grains. The grains themselves also display a difference in activity across the crystal orientations with Pt(100) proving to be the most active for formic acid oxidation.