Cited by 38Electrocatalysts for Energy ConversionCatalytic Processes in Materials ScienceFuel Cells and Related Materials

Oxidative Self-Assembly of Au/Ag/Pt Alloy Nanoparticles into High-Surface Area, Mesoporous, and Conductive Aerogels for Methanol Electro-oxidation

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Sarkar, Rajib, Farghaly, Ahmed A., Arachchige, Indika U.·2022·Chemistry of Materials

Abstract

The ability to assemble nanoparticles (NPs) into functional nanostructures is critical for the advancement of nanoscience. However, common assembling techniques utilize organic ligands or biomolecules, which are detrimental for charge transport and interparticle coupling and impede the efficient integration of low-dimensional properties. Herein, we report a methodology for the self-supported assembly of ultrasmall (3–6 nm) Au/Ag/Pt alloy NPs into large, freestanding alloy superstructures (aerogels) that exhibit direct NP connectivity, high surface area (125 ± 0.43 to 142 ± 0.93 m 2 /g) and mesoporosity (21.6 ± 2.2 nm), and superior electrocatalytic activity for the methanol oxidation reaction (MOR). Precursor Au/Ag/Pt alloy NPs and hydrogels were synthesized via a stepwise galvanic replacement reaction (GRR) of glutathione (GSH)-coated Ag NPs, followed by oxidative removal of the surfactant ligands. The composition of alloy aerogels was tuned by varying the oxidant/GSH molar ratio, which governs the extent of Ag dealloying with in situ generated HNO 3 and increases the exposure of Au and Pt on the aerogel surface. The alloy aerogels exhibit superior MOR mass activity, which is 21.4 and 2.5 times higher than that of the precursor NPs and commercial Pt (40 wt %)/C electrocatalysts, respectively. The MOR surface-specific activity (MOR-SSA) of the aerogels was improved by >17% when the Pt content was increased from 22.4 to 31.2%. The aerogels exhibit improved electronic conductivity and enhanced tolerance for carbonaceous byproducts and maintained ∼94% of the initial MOR activity at −0.3 V for 24 h in alkaline medium. The interconnected porous superstructure of the aerogel provides a facile conduit for molecules to reach the pristine active surface, whereas the presence of oxophilic Au promotes the dissociative adsorption of methanol, providing the Au/Ag/Pt alloy aerogel as a high-efficiency, durable electrocatalyst for the next generation of energy conversion studies.

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  1. [16]16. Urban, J. J.; Talapin, D. V.; Shevchenko, E. V.; Murray, C. B. Self-Assembly of PbTe Quantum Dots into Nanocrystal Superlattices and Glassy Films. J. Am. Chem. Soc. 2006, 128, 3248-3255.
  2. [28]28. Nahar, L.; Arachchige, I. U. Sol-Gel Methods for the Assembly of Metal and Semiconductor Nanoparticles. JSM Nanotechnol. Nanomed. 2013, 1, 1004.

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Authors
Sarkar, R., Farghaly, A. A., & Arachchige, I. U.
Affiliations
  • Virginia Commonwealth University (US)
  • Argonne National Laboratory (US)
Corresponding author
Arachchige, Indika U.
Venue
Chemistry of Materials
Published
2022-06-24
Volume
34
Issue
13
Pages
5874-5887
ISSN
  • 0897-4756 (ISSN-L)
  • 1520-5002
OpenAlex
W4283384062
Cited by
38
References
94
Citations by year
2026: 3 · 2025: 9 · 2024: 11 · 2023: 13 · 2022: 2
FWCI
1.58
Type
journal article
Language
en
Open access
Locations
  • Chemistry of Materials (publishedVersion)
  • OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion)
Funders
  • Division of Chemistry (CHE-1851916)
  • Virginia Commonwealth University
  • Department of Chemistry, Virginia Commonwealth University
Topics
  • Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Electrocatalysts for Energy Conversion
  • Physical Sciences › Materials Science › Materials Chemistry › Catalytic Processes in Materials Science
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Fuel Cells and Related Materials
Keywords
methanol electrooxidation, galvanic replacement, high surface area, electrocatalysts, platinum loading, electronic conductivity, alkaline stability

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