Hydrogen Peroxide Formation Rates in a PEMFC Anode and Cathode: Effect of Humidity and Temperature

TL;DR

This study investigates how humidity and temperature influence hydrogen peroxide formation in PEM fuel cells by analyzing oxygen reduction reactions on a rotating ring disc electrode, revealing dependencies on oxygen concentration and water activity.

Contribution

It provides new insights into the effects of humidity and temperature on H2O2 formation rates and selectivity in PEMFCs through experimental analysis of ORR on a RRDE.

Findings

H2O2 formation rates depend linearly on oxygen concentration.

H2O2 formation rates depend quadratically on water activity.

H2O2 selectivity increases with decreasing humidity.

Abstract

Hydrogen peroxide (H2O2) formation rates in a proton exchange membrane (PEM) fuel cell anode and cathode were estimated as a function of humidity and temperature by studying the oxygen reduction reaction (ORR) on a rotating ring disc electrode (RRDE). Fuel cell conditions were replicated by depositing a film of Pt/Vulcan XC-72 catalyst onto the disk and by varying the temperature, dissolved O2 concentration and the acidity levels in hydrochloric acid (HClO4). The HClO4 acidity was correlated to ionomer water activity and hence fuel cell humidity. The H2O2 formation rates showed a linear dependence on oxygen concentration and square dependence on water activity. The H2O2 selectivity in ORR was independent of oxygen concentration but increased with decrease in water activity (i.e., decreased humidity). Potential dependent activation energy for the H2O2 formation reaction was estimated from data obtained at different temperatures.