Towards a realistic prediction of catalyst durability from liquid half-cell tests

Abstract

Liquid half-cell measurements provide a convenient laboratory method for the determination of relevant parameters of electro-catalysts applied in e.g. polymer electrolyte membrane fuel cells. While these measurements may be effective...

Enhancing the Performance of Shape-Controlled Octahedral Rhodium-Doped PtNi Nanoalloys inside Hydrogen–Air Fuel Cell Cathodes Using a Rational Design of Catalysts, Supports, and Layering

“…As a result, the ECSA has lessened and the limiting current decreased after the AST. While these results seem to suggest instability at high temperatures, however, the interpretation of the behavior of PtNi alloy in such a condition is limited so far since most of the RDE experiments running under 80° were conducted using pure Pt catalysts. ,, Since the behavior in MEA might be different from that in liquid electrolyte, we tested our catalyst in MEA.…”

Degradation of Pt-Based Cathode Catalysts Upon Voltage Cycling in Single-Cell PEM Fuel Cells Under Air or N2 at Different Relative Humidities

“…In general, however, the observed increase of the i mass 0.9V values with decreasing ECSA is what one would expect for an increase of the Pt particle size 49 that occurs over the course of V-cycling ASTs. 1,7 Comparison of the H 2 /Air performance after H 2 /N 2 versus H 2 /Air V-cycling ASTs.-Figure 10 shows the BOT differential-flow H 2 /Air (2000/5000 nccm) performance of all tested MEAs at 80 °C/100% RH and 170 kPa abs (black symbols/line). After 30 k (EOT) cycles of the H 2 /N 2 (solid symbols) and H 2 /Air (open symbols) V-cycling ASTs conducted at 80 °C and different RH conditions (marked in the figure), the trend in the H 2 /Air performance losses follows the above observed losses of the Pt ECSA (Fig.…”

“…In these, the cathode electrode of the membrane electrode assembly (MEA) is polarized in a PEMFC single-cell between an upper potential limit (UPL), aimed to resemble the cathode potential during idle or lowpower operation, and a lower potential limit (LPL), aimed to resemble the cathode potential during peak power. 1,3 Alternatively, the voltage cycling degradation of PEMFC catalysts has also been studied extensively by rotating disk electrode (RDE) measurements 4 as well as by using an electrochemical scanning flow cell (SFC) coupled to an ICP-MS. 5,6 However, while these tests conducted in liquid acidic electrolytes provide valuable insights into catalyst durability particularly when conducted at PEMFC relevant temperatures, 7 the transport conditions in an actual MEA are different from those in the thin-film catalyst layers used for RDE or flow cell experiments, so that MEA based measurements are generally considered to more closely represent PEMFC system field data. 8 In MEAs, voltage cycling ASTs are most commonly conducted with H 2 /N 2 feeds (at anode/cathode), 9 whereby the cathode potential (E cath ) is essentially identical with the cell voltage (E cell ), since the potential of the Pt/C based H 2 anode remains at the reversible hydrogen electrode reference potential (RHE) due to its fast hydrogen oxidation/evolution kinetics 10 and since ohmic resistances are negligible at the small current densities during H 2 /N 2 voltage cycling.…”

Adjusting the Operational Potential Window as a Tool for Prolonging the Durability of Carbon-Supported Pt-Alloy Nanoparticles as Oxygen Reduction Reaction Electrocatalysts

“…For instance, most MEA studies in the literature , usually follow the US DoE degradation protocol for fuel cells and fuel cell components . The protocol consists of 30,000 trapezoidal wave cycles in a voltage range similar to that which is expected for an automotive drive cycle (0.6–0.95 V), with a 3 s hold at each potential, at 80 °C, thus simulating close-to-real operational conditions regarding the operational lifetime of 5000 h as the current target for LDVs. , On the other hand, apart from rare studies such as the recent one presented by Imhof et al, RDE stability studies typically vary with respect to this protocol.…”