Improved Catalyst for Formic Acid Fuel Cells

Abstract

Direct Formic Acid fuel cells (DFAFCs) can enhance the efficiency of portable devices that currently rely on battery power; however, current DFAFC anode catalysts either have high parasitic overpotentials and/or deactivate over time. One of the current state-of-the-art anode catalysts are carbon supported platinum nanoparticles modified with a sub-monolayer of bismuth (Pt/C-Bi) that are deactivated during potential cycling. When using bismuth as a Pt catalyst activator, there is a tendency to lose performance over time as the bismuth oxidizes and is lost from the Pt surface. The objective of this research project was to replace bismuth with strongly adsorbed Citric Acid (C_6 H_8 O_7) to improve the performance durability of the catalyst. This research focused on ex-situ methodology evaluating formic acid electro-oxidation performance and sustained activity using a polycrystalline platinum catalyst electrode modified with a submonolayer (%ML) of citric acid (0-80% surface coverage). The overpotentials for formic acid electro-oxidation were evaluated through the use of linear sweep voltammetry.  The durability of the modified electrode was investigated using potentiostatic holds at 0.2V vs RHE. Using these methods, modified catalyst Pt-% ML citric acid were investigated as an alternative to Pt-54% ML Bi for possible future use in DFAFCs.