Study of the acetonitrile poisoning of platinum cathodes on proton exchange membrane fuel cell spatial performance using a segmented cell system

Abstract

Due to the wide applications of acetonitrile as a solvent in the chemical industry, acetonitrile can be present in the air and should be considered a possible pollutant. In this work, the spatial proton exchange membrane fuel cell performance exposed to air with 20 ppm CH 3 CN was studied using a segmented cell system. The injection of CH 3 CN led to performance losses of 380 mV at 0.2 A cm 2 and 290 mV at 1.0 A cm 2 accompanied by a significant change in the current density distribution. The observed local currents behavior is likely attributed to acetonitrile chemisorption and the subsequent two consecutive reduction/oxidation reactions. The hydrolysis of CH 3 CN and its intermediate imine species resulted in NH 4 + formation, which increased the high-frequency resistance of the cell and affected oxygen reduction and performance. Other products of hydrolysis can be oxidized to CO 2 under the operating conditions. The reintroduction of pure air completely recovered cell performance within 4 h at 1.0 A cm 2 , while at 0.2 A cm 2 the cell recovery was only partial. A detailed analysis of the current density distribution, its correlation with spatial electrochemical impedance spectroscopy data, possible CH 3 CN oxidation/reduction mechanisms and mitigation strategies are presented and discussed.

Impact of the Cathode Pt Loading on PEMFC Contamination by Several Airborne Contaminants

“…After contamination, the high-frequency intercept returns to its original value, and both main loops decrease in size to a diameter that is smaller than the original value. These impedance spectra agree with prior results [25][26][27][28]. However, smaller kinetic and mass transfer loops are inconsistent with a complete cell voltage recovery (Figure 1a, Table 1).…”

“…For acetonitrile, the cell voltage after recovery coincided with the value before contaminant injection. Acetonitrile contamination and recovery transients are qualitatively and quantitatively consistent with prior results [23,[25][26][27][28]. At irregular intervals and during all baseline, contamination, and recovery stages, cell voltage transients were minimally disrupted for a short period by impedance spectroscopy measurements and the superimposition of a current signal of a small amplitude and variable frequency.…”

“…For naphthalene, the cell voltage transient was interrupted before a steady state was obtained (Figure 1f), which also led to a low-frequency artefact that could not be fitted to the equivalent circuits of Figure 3a-c. The impedance spectra agree with the prior results for acetonitrile [25][26][27][28], acetylene [36][37][38], bromomethane [28][29][30], isopropanol [31], methyl methacrylate [31], naphthalene [40], and propene [28,31,41]. Molecules 2020, 25 and structural modifications to the catalyst layer that are relatively more impactful for the lower catalyst loading.…”

Acetonitrile Adsorption on Pt Single-Crystal Electrodes and Its Effect on Oxygen Reduction Reaction in Acidic and Alkaline Aqueous Solutions

“…The effect of acetonitrile was also studied in a PEMFC system showing performance losses and changes in current density distribution. 22 In this work, the adsorption and surface reactivity of acetonitrile on Pt(111) and…”

A Detrimental Effect of Acetonitrile on the Kinetics of Underpotentially Deposited Hydrogen and Hydrogen Evolution Reaction, Examined on Pt Electrode in H2SO4 and NaOH Solutions

“…Acetonitrile, CH 3 CN (AcN) is a simple-structure, highly polar and volatile organic solvent, commonly used in numerous industrial applications, including: extraction, plastics molding and casting and battery technologies. Its presence in the air could have a substantial detrimental effect on the catalytic performance of otherwise highly reactive, noble metal-based electrochemical catalysts [7][8][9][10][11][12].…”