In-Situ Monitoring of Particle Growth at PEMFC Cathode under Accelerated Cycling Conditions

An in-situ method to measure changes in catalyst particle size at the cathode of a proton exchange membrane fuel cell is demonstrated.Synchrotron X-rays, 58 keV, were used to measure the pair distribution function on an operating fuel cell and observe the growth of catalyst particles under accelerated degradation conditions.The stability of Pt/C and PtCo/C with different initial particle sizes was monitored over 3000 potential cycles.The increase in particle size was fit to a linear trend as a function of cycles.The most stable electrocatalyst was found to be the alloyed PtCo with the larger initial particle size.