Novel fuel blends facilitating the electro-oxidation of formic acid at a nano-Pt/GC electrode

Abstract

This paper addresses the promoting effect of the electrooxidation of formic acid (FAO) at a nano-Pt/GC electrode in the presence of selected low molecular weight alcohols (R–OH) as blending components. That is, blending FA with different molar ratios of methanol (MeOH), ethanol (EtOH), ethylene glycol (EGOH) and isopropanol (PrOH) resulted in a significant enhancement of the direct FAO to CO₂ (desired pathway) with a concurrent depression of the amount of CO produced from the “non-faradaic” dissociation of FA. Moreover, a favorable negative shift of the onset potential of the direct FAO peak at the nano-Pt/GC electrode is observed. Fuel utilization (FU = amount of charge consumed during the oxidation process per mole of fuel) and the turnover number (TON = number of FA molecules oxidized per platinum site per second) are significantly enhanced as well for FAO in the various FA/R–OH blends compared to pure FA. That is, the use of equimolar amounts of FA with either EtOH, MeOH, EGOH or PrOH resulted in a facile FAO at the nano-Pt/GC electrode of about 9, 7, 5 and 4 times higher FU compared to pure FA, respectively. Similar increase of TON is observed as well. The blending component is believed to adsorb at the Pt surface sites and thus disfavor the “non-faradaic” dissociation of FA to CO. Additionally; it might induce the CH-down adsorption orientation of FA, thus favoring FAO to CO₂. The enhanced oxidation activity indicates that this fuel blend is a promising fuel system.