Catalyst Poisoning Property of Sulfonimide Acid Ionomer on Pt (111) Surface

Abstract

The catalyst poisoning property of a novel ionomer, NBC4, which has two sulfonimide acid groups in its side chain ended with a perfluorobutane, instead of sulfonic acid groups as Nafion does, was theoretically and experimentally compared with that of Nafion. A density functional theory combined with a continuum electrolyte theory showed that the adsorption is weaker for sulfonimide anion than for sulfonate anion on Pt (111) surface. Electrochemical measurements using Pt (111) surfaced single crystal electrodes covered with the ionomer films showed the weaker anion adsorption and higher ORR activity by ca. 50% at 0.82 V vs the reversible hydrogen electrode for NBC4 than for Nafion.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 131.215.225.9 Downloaded on 2015-06-21 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 131.215.225.9 Downloaded on 2015-06-21 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 131.215.225.9 Downloaded on 2015-06-21 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 131.215.225.9 Downloaded on 2015-06-21 to IP

Analysis of the Microstructure Formation Process and Its Influence on the Performance of Polymer Electrolyte Fuel‐Cell Catalyst Layers

“…If the cathode catalyst ink is water rich, the apparent ORR area‐specific activity of the MEA significantly increases. Many researchers have indicated that the ionomer is adsorbed on the platinum surface even under aqueous measurement conditions and is likely to suppress the adsorption of oxygen molecules on the platinum surface . Related to the phenomenon, it was reported that ionomer coverage on platinum can have a negative impact on the apparent ORR area‐specific activity .…”

Oxygen Reduction Reaction Measurements on Platinum Electrocatalysts Utilizing Rotating Disk Electrode Technique

“…Several complementary studies have reported the detrimental effects of sulfonate anion adsorption. [78][79][80] A common factor in a majority of the TF-RDE studies for Pt/C catalysts encountered in the literature is the incorporation of Nafion ionomer either mixed in with the catalyst ink formulation or applied as a cap over the dried catalyst film on RDE disk. 6,[13][14][15]17,[48][49][50][51]61,62,69,[81][82][83][84] However, the ORR activity values that are measured with added Nafion represent a complex, poorly defined, and variable electrochemical interface that can be represented as "Pt/C | discontinuous Nafion film soaked in 0.1 M HClO 4 , free 0.1 M HClO 4 ".…”

MgO-Templated Mesoporous Carbon as a Catalyst Support for Polymer Electrolyte Fuel Cells

“…Pt/Vulcan slightly showed higher coverages (12-14%) than Pt/CNovels (9-11%). Considering that fully Nafion-covered Pt(111) single crystal showed roughly 10% [6,10,13] sulfonate adsorption and that Pt/Vulcan is likely fully covered as well, The slightly lower sulfonate adsorptions of CNovels suggest that a considerable part of electrochemically available Pt surface is not covered by Nafion. Current-Voltage (i-V) performances in a low current density region and specific activities (0.9V) are also compared in Figures 10 and 11 (average of three samples with standard error), respectively.…”

“…Considering a significant part of Pt particles are not covered with the ionomer but are reachable by proton with water, these high activities of Pt/CNovels in MEA can be attributed to high activity of non-covered and non-poisoned Pt surface. Although a quantitative discussion on the ionomer poisoning effect is not possible, these significantly different trend in the activities results are not inexplicable considering the fact that fully covered Pt(111) with 10% sulfonic adsorption exhibited 80% activity loss [6,10,13]. Overall i-V performances are shown in Figure 12.…”

“…A possible approach tackling these unfavorable effects of ionomers is to modify the molecular structure of ionomers to less-adsorptive ones [13]. Another approach is to change the morphology of the substrate, carbon.…”