Mass-transport properties of electrosprayed Pt/C catalyst layers for polymer-electrolyte fuel cells

Electrochemical pressure impedance spectroscopy for investigation of mass transfer in polymer electrolyte membrane fuel cells

“…Mass transfer processes in fuel cells cover various physicochemical phenomena in the different cell components, involving gaseous reactants or the water produced, as exemplified below.  In the catalyst layer, in addition to the refined modelling approaches of the catalyst layer, one can mention use of EIS for evaluation of improved catalyst layer deposition [10], or fundamental investigations on the importance of the nature of the pore filling liquid [11] or the specific roles of catalyst clusters and carbon support [12]. Moreover, in addition to its transport in the catalyst layer pores, the reacting gas dissolves in the thin ionomeric layer attached to the catalyst cluster for possible charge transfer, accompanied by H + transfer: the set of process is often viewed by EIS as an overall single phenomenon, with signature in the high-frequency loop.…”

“…EIS is usually not conducted alone to characterise the operation or the state of health of fuel cells: other electrochemical techniques e.g. voltage measurement at fixed current density (cd), cyclic or sweep voltammetry are routinely employed in complement to EIS, as well as -more recently -estimation of the limiting cd [10,24]. Mechanical, analytical, spectroscopic and microscopic techniques can help in establishing reliable diagnosis on a fuel cell [25,26].…”

Sustainable Platinum Recycling through Electrochemical Dissolution of Platinum Nanoparticles from Fuel Cell Electrodes

“…During the cathodic sweep, Pt‐dissolution takes place through dissolution/chloride complexing of the Pt‐Oxide layer, leading to a fresh Pt surface for potentials ranging between 1.0 and 0.4 V. The potential value sufficient to dissolve the Pt‐oxide layer completely may be varied by varying the reaction kinetics by changing the parameters such as scan rate, Pt‐nanoparticle/support interface, etc. The local potential at the nanoparticle surface may differ significantly from the externally applied potential due to the insolating property of the proton conductive polymer and the ionomer (thin film) encapsulating catalyst interface structure, where there is an increased electron transport resistance at the catalyst/support/ionomer interface . Therefore, the values reported in the study is specific for the PEMFC electrodes; nevertheless, the relative value and changing trend is representative and can be used for general understanding.…”

“…The local potential at the nanoparticle surface may differ significantly from the externally applied potential due to the insolating property of the proton conductive polymer and the ionomer (thin film) encapsulating catalyst interface structure, [48][49][50] where there is an increased electron transport resistance at the catalyst/support/ionomer interface. [49,51] Therefore, the values reported in the study is specific for the PEMFC electrodes; nevertheless, the relative value and changing trend is representative and can be used for general understanding. Further, as the cathodic peaks corresponding to Cl À desorption/ Pt-Oxide reduction during negative-going scan in 0.1 M HCl (Figure 3a) shift towards negative potentials with increasing the upper potential limit, the potential range for dissolution may be optimized further through choosing a smaller potential step (e. g. 100 or 50 mV) for the lower/upper potential limit study, instead of a potential step of 200 mV used in the present study.…”

Cathode Design for Proton Exchange Membrane Fuel Cells in Automotive Applications

“…Besides, the transport of liquid water in the CL also affects the membrane and electrode humidification states, as well as the internal resistance and catalyst efficiency that determine fuel cell performance [135]. A large operating current density may result in oxygen starvation at the catalyst surface because of the high water formation rate at the cathode.…”