Visualization of the oxygen partial pressure in a proton exchange membrane fuel cell during cell operation with low oxygen concentrations

The oxygen starvation was investigated in a single-serpentine proton exchange membrane fuel cell (PEMFC) at low oxygen concentrations of 3, 5, and 10% in air. At the voltage lower than 0.6 V, the cell performance abruptly decreased at all oxygen concentrations, but most significantly at 3%. To investigate the processes of the oxygen starvation, the oxygen partial pressure (p(O-2)) on the gas diffusion layer (GDL) at low oxygen concentrations (Phi(O-2)) of 3, 5, and 10% in air was visualized at the cathode in a running single-serpentine PEMFC by using an oxygen-sensitive dye coated on the GDL. p(O-2) continuously lowered in the operating fuel cell along the gas flow channel. At Phi(O-2) = 3 and 5% and at oxygen utilizations higher than 90%, p(O-2) on the GDL became 0 kPa and susceptible to degradation. The evolution of hydrogen at the cathode was proposed, which might have chemically consumed oxygen near the outlet. Also in a stack, the influence of this hydrogen evolution prior to the hydrogen pumping must be considered.

Automated summary

The investigation revealed that PEMFC performance significantly decreases at low oxygen concentrations, with oxygen partial pressure decreasing gradually, possibly influenced by hydrogen evolution.