Iridium As Catalyst and Cocatalyst for Oxygen Evolution/Reduction in Acidic Polymer Electrolyte Membrane Electrolyzers and Fuel Cells

Abstract

Among noble metal electrocatalysts, only iridium presents high activity for both the oxygen reduction reaction (ORR) in acid medium, in the oxide form, and the oxygen evolution reaction (OER) in acid medium, alloyed with first row transition metals. Indeed, platinum, the best catalyst for the ORR, has poor activity for the OER in any form, and ruthenium, the best catalyst for the OER, in the oxide form, possess poor activity for the ORR in any form. In this work, an overview of the application of Ir and Ir-containing catalysts for the OER in protonexchange membrane water electrolyzer anodes, for the ORR in proton exchange membrane fuel cell cathodes, and for both OER and ORR in unit regenerative fuel cell oxygen electrodes is presented.

Activity and Stability of Electrochemically and Thermally Treated Iridium for the Oxygen Evolution Reaction

“…Since no inexpensive and suitable replacement for Ir has been found so far, current research efforts are directed toward a more efficient utilization of Ir based catalysts. 4 Nanoparticulated materials efficiently dispersed on a support, [5][6][7][8] highly porous layers, [9][10][11] core shell 12,13 and mixed oxide systems [14][15][16] have been suggested to reduce the loading of expensive elements. An alternative way is the structural modification of iridium oxides, e.g.…”

Screening Bifunctional Pt Based NSTF Catalysts for Durability with the Rotating Disk Electrode: The Effect of Ir and Ru

“…Instead the electrochemical conversion of metallic Ir to Ir oxide probably plays a role. The review by Antolini 46 lists many studies documenting the ORR activity of Ir, IrO 2 , and their alloys, but the relative ORR activities of Ir and electrochemical formed IrO 2 under identical conditions has not been studied. The trend of the Ir on Pt samples shown in Figure 7B could be because anodically oxidized IrO 2 has a better ORR activity than its metallic precursor.…”

Systematic Analysis for the Effects of Atmospheric Pollutants in Cathode Feed on the Performance of Proton Exchange Membrane Fuel Cells

“…[4][5][6] Recently, many studies of PEMFCs have focused on the development of inexpensive and durable materials/components in PEMFCs. [7][8][9][10][11][12] In addition, the effect of impurities in hydrogen feed has been researched mainly for the utilization of reformate gases. 13 However, the effect of atmospheric pollutants in cathode feeds, such as sulfur dioxide (SO 2 ), ammonia (NH 3 ), nitrogen dioxide (NO 2 ), and carbon monoxide (CO), has received less attention, even though it is considered a practical issue for the performance and durability of FCEVs.…”