Rational Design of Rhodium–Iridium Alloy Nanoparticles as Highly Active Catalysts for Acidic Oxygen Evolution

Journal Article · Thu Oct 31 00:00:00 UTC 2019 · ACS Nano

DOI:https://doi.org/10.1021/acsnano.9b06244· OSTI ID:1774914

Guo, Hongyu ^[1]; Fang, Zhiwei ^[2]; Li, Hao ^[2]; Fernandez, Desiree ^[2]; Henkelman, Graeme ^[2]; Humphrey, Simon M. ^[2]; Yu, Guihua ^[2]

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1. Univ. of Texas, Austin, TX (United States); The University of Texas at Austin
2. Univ. of Texas, Austin, TX (United States)

The oxygen evolution reaction (OER) is pivotal for renewable energy conversion and storage devices, such as water electrolyzers and rechargeable metal–air batteries. However, the rational design of electrocatalysts with suitably high efficiencies and stabilities in strongly acidic electrolytes remains a significant challenge. Here, we show the demonstration of sub-10 nm, composition-tunable Rh–Ir alloy nanoparticles (NPs) prepared using a scalable microwave-assisted method as superior acidic OER catalysts. The OER activities showed a volcano-shaped dependence on Ir composition, with Ir-rich NPs (Ir ≥ 51%) achieving better OER performance than pure Ir NPs, as reflected by lower overpotentials and higher mass activities. Most significantly, Rh₂₂Ir₇₈ NPs achieved a maximum mass activity of 1.17 A mg^–1Ir at a 300 mV overpotential in 0.5 M H₂SO₄, which corresponds to a 3-fold enhancement relative to pure Ir NPs, making it one of the most active reported OER catalysts under acidic conditions. Density functional theory calculations reveal that owing to the synergy of ensemble and electronic effects by alloying a small amount of Rh with Ir, the binding energy difference of the O and OOH intermediates is reduced, leading to faster kinetics and enhanced OER activity. Furthermore, Rh–Ir alloy NPs demonstrated excellent durability in strongly acidic electrolyte. Furthermore, this work not only provides fundamental understandings relating to composition–electrochemical performance relationships but also represents the rational design of highly efficient OER electrocatalysts for applications in acidic media.

• Research Organization: Univ. of Texas, Austin, TX (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0019019
• OSTI ID: 1774914
• Journal Information: ACS Nano, Journal Name: ACS Nano Journal Issue: 11 Vol. 13; ISSN 1936-0851
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
acidic electrolyte
alloys
catalysts
ensemble effect
microwave synthesis
oxygen evolution reaction
precursors
radiology
rhodium−iridium alloy
transition metals