Advances in iridium nano catalyst preparation, characterization and applications

Ali, Imran; Al-Ghamdi, Khalaf; Al-Wadaani, Fahd

doi:10.1016/j.molliq.2019.02.050

Cited by 45 publications

(13 citation statements)

References 107 publications

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“…Ir is equally scarce and recently has become even more expensive than Pt . The motivation behind developing PtIr catalysts is not necessarily the optimization of the binding energy of reaction intermediates but rather the fact that Ir-oxide is an active catalyst for the oxygen evolution reaction (OER). , Bifunctional ORR/OER electrocatalysts are suggested to improve the stability of PEMFC cathode catalysts because under high potential excursions reached during startup and shutdown, the OER competes with and thus mitigates the oxidation of the carbon support to carbon dioxide, the latter being extremely detrimental to the catalyst stability. Furthermore, bifunctional ORR/OER electrocatalysts are suggested for the so-called unitized regenerative fuel cells (URFCs).…”

Section: Introductionmentioning

confidence: 99%

Bifunctional Pt-IrO₂ Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles versus Nanocomposite Catalysts

Quinson

Zhang

et al. 2021

ACS Catal.

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In the present study, different concepts for the development of bifunctional oxygen reduction reaction/oxygen evolution reaction (ORR/OER) electrocatalysts are explored and compared. Bifunctional ORR/OER catalysts are often suggested to improve the stability during startup and shutdown of fuel cells. Furthermore, they have been proposed for the so-called unitized regenerative fuel cells (URFCs) that would allow a closed loop system to use and produce hydrogen on demand. We compare the electrocatalytic performance of conventional Pt x Ir y alloy nanoparticles (NPs) with Pt–IrO2 NP composites (nanocomposites), both immobilized onto a commercial carbon support. The Pt–IrO2 nanocomposites thereby consist of a mixture of Pt NPs and IrO2 NPs. By probing the electrocatalytic performance before and after exposing the electrocatalysts to accelerated degradation tests (ADTs), it is shown that the Pt–IrO2 nanocomposite concept offers advantages but also some disadvantages over the conventional alloy concept. In particular, it is shown that while the nanocomposites are initially less active for the ORR because of an interparticle effect, their performance is less affected by the ADTs. However, all the tested catalysts experience a decline of the Ir/Pt ratio upon ADT treatment, highlighting the limiting value of Ir as an OER catalyst for startup–shutdown protection in fuel cells as well as the challenging stability requirements for URFCs.

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Section: Introductionmentioning

confidence: 99%

Bifunctional Pt-IrO₂ Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles versus Nanocomposite Catalysts

Quinson

Zhang

et al. 2021

ACS Catal.

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“…5,6 Following this approach, numerous transition metals, such as Ni, 7,8 Pd, 9 Ru, 10,11 Pt, 12 Co, 8 Mn, 8 Fe, 8 have been doped on the B-site of stoichiometric or A-site deficient mixed perovskite oxides and subsequently exsolved under a range of reducing atmospheres or through fast electrochemical reduction. Among the transition metals, iridium is a scarce but key element being used in a variety of applications 13 including water splitting reactions, [14][15][16][17] fuel cells, 18,19 hydrogenation reactions, 20 methane reformation 21,22 and auto-motive exhaust catalysis. [23][24][25][26] Specifically, CO oxidation applied in air purification and pollution control in automotive exhaust uses more than 60% of the annual production of noble metals.…”

Section: Introductionmentioning

confidence: 99%

Exsolution of Catalytically Active Iridium Nanoparticles from Strontium Titanate

Calì

Kerherve

Naufal

et al. 2020

ACS Appl. Mater. Interfaces

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The search for new functional materials that combine high stability and efficiency with reasonable cost and ease of synthesis is critical for their use in renewable energy applications. Specifically in catalysis, nanoparticles, with their high surfaceto-volume ratio, can overcome the cost implications associated with otherwise having to use large amounts of noble metals. However, commercialized materials, i.e. catalytic nanoparticles deposited on oxide supports, often suffer from loss of activity due to coarsening and carbon deposition during operation. Exsolution has proven to be an interesting strategy to overcome such issues.Here the controlled emergence, or exsolution, of faceted iridium nanoparticles from a doped SrTiO3 perovskite is reported and their growth preliminary probed by in situ electron microscopy. Upon reduction of SrIr0.005Ti0.995O3 the generated nanoparticles show embedding into the oxide support, therefore preventing agglomeration and subsequent catalyst degradation. The advantages of this approach are the extremely low noble metal amount employed (~0.5% weight) and the catalytic activity reported during CO oxidation tests, where the performance of the exsolved SrIr0.005Ti0.995O3 is compared to the activity of a commercial catalyst with 1% loading (1% Ir/Al2O3). The high activity obtained with such low-doping shows the possibility for scaling up this new catalyst, reducing the high cost associated with iridium-based materials.Image analysis and calculations; XPS supplementary data; STEM-EDX maps of as-synthesised Ir0.5-STO (PDF)

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“…22 The motivation behind developing PtIr catalysts is not necessarily the optimization of the binding energy of reaction intermediates but rather the fact that Ir-oxide is an active catalyst for the oxygen evolution reaction (OER). 23 Bifunctional ORR / OER electrocatalysts are expected to improve the stability of PEMFCs cathode catalysts since under high potential excursions reached during startup and shutdown, the OER competes with and thus mitigates the oxidation of the carbon support to carbon dioxide, the latter being extremely detrimental to the catalyst stability. Furthermore, bifunctional ORR / OER electrocatalysts might enable so-called unitized regenerative fuel cells (URFCs).…”

Section: Introductionmentioning

confidence: 99%

Bifunctional Pt-IrO2 Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles vs. Nanocomposite Catalysts

Du¹,

Quinson²,

Zhang³

et al. 2020

Preprint

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In the present study different concepts for the development of bifunctional oxygen reduction reaction / oxygen evolution reaction (ORR / OER) electrocatalysts are explored and compared. Bifunctional ORR / OER catalysts are often suggested to improve the stability during startup and shutdown of fuel cells. Furthermore, they are proposed for so-called unitized regenerative fuel cells (URFCs) that would allow a closed loop system to use and produce hydrogen on demand. We compare the electrocatalytic performance of conventional PtxIry alloy nanoparticles (NPs) with Pt – IrO2 NP composites (nanocomposites), both immobilized onto a commercial carbon support. The Pt – IrO2 nanocomposites thereby consist of a mixture of Pt NPs and IrO2 NPs. By probing the electrocatalytic performance before and after exposing the electrocatalysts to accelerated degradation tests (ADTs) it is shown that the Pt – IrO2 nanocomposite concept offers advantages but also some disadvantages over the conventional alloy concept. In particular it is shown that while the nanocomposites are initially less active for the ORR due to an interparticle effect, their performance is less affected by the ADTs. However, all tested catalysts experience a decline of the Ir / Pt ratio upon the ADTs treatment, highlighting the challenging stability requirements for URFCs.

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Advances in iridium nano catalyst preparation, characterization and applications

Cited by 45 publications

References 107 publications

Bifunctional Pt-IrO₂ Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles versus Nanocomposite Catalysts

Bifunctional Pt-IrO₂ Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles versus Nanocomposite Catalysts

Exsolution of Catalytically Active Iridium Nanoparticles from Strontium Titanate

Bifunctional Pt-IrO2 Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles vs. Nanocomposite Catalysts

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Advances in iridium nano catalyst preparation, characterization and applications

Cited by 45 publications

References 107 publications

Bifunctional Pt-IrO2 Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles versus Nanocomposite Catalysts

Bifunctional Pt-IrO2 Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles versus Nanocomposite Catalysts

Exsolution of Catalytically Active Iridium Nanoparticles from Strontium Titanate

Bifunctional Pt-IrO2 Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles vs. Nanocomposite Catalysts

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Product

Resources

About

Bifunctional Pt-IrO₂ Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles versus Nanocomposite Catalysts

Bifunctional Pt-IrO₂ Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles versus Nanocomposite Catalysts