The assembly of nanoparticles (NPs) into functional macrostructures while retaining the nanoparticulate properties intact is a critical need for the development of NPs-based devices. Existing methods use organic linkers which impede the interparticle coupling and electron transport, detrimental to practical applications. Herein, we report the self-assembly of ultra-small (3-6 nm) glutathione coated Au/Ag/Pt NPs into an aerogel superstructure via oxidative removal of the surface functionalities for electrocatalytic methanol oxidation reaction (MOR). Primary Au/Ag/Pt alloy NPs with tunable compositions were synthesized by stepwise galvanic-replacement-reaction of preformed glutathione-Ag NPs. Elemental composition and structural properties of the aerogels were finely tuned by changing the oxidant/surfactant molar ratio, which dictates the extent of Ag dealloying by in-situ produced HNO<sub>3</sub> and selectively increases the exposure of Pt and Au on the aerogel surface. The synthesized aerogels exhibit pristine metallic surfaces, high surface area (142±0.93 m<sup>2</sup>/g) and mesoporosity (21.6±2.2 nm). As-synthesized Au/Ag/Pt aerogels exhibited 21.4 and 2.5 times higher electrocatalytic activity for MOR than the discrete precursor NPs and commercial Pt/C, respectively. The aerogel displayed a higher steady-state current density at -0.3V for 24 h, retaining 94% of the initial MOR activities suggesting higher tolerance to catalyst poisoning and stability. The interconnected NPs and pores offer facile transport of charge and analytes throughout the aerogel structure whereas the influence of alloying minimizes the catalyst poisoning effect, enabling the Au/Ag/Pt aerogel to be a high-efficiency electrocatalyst.

Oxidation induced self-assembly of Au/Ag/Pt alloy nanoparticles into highly porous and conducting aerogel monolith for alcohols electro-oxidation.

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.