Elsevier

Ultrasonics Sonochemistry

Volume 79, November 2021, 105753
Ultrasonics Sonochemistry

Unsupported gold nanocones as sonocatalytic agents with enhanced catalytic properties

https://doi.org/10.1016/j.ultsonch.2021.105753Get rights and content
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Highlights

  • Submicron gas stabilising Au nanocones (gs-AuNCs) readily nucleate cavitation.

  • Cavitation activates gs-AuNCs to degrade of 4-nitrophenol and methylene blue.

  • Degradation kinetics with gs-AuNC are 200-fold faster than similarly sized catalysts.

  • Cavitation events at catalyst sites enhanced functionality of submicron gs-AuNCs.

Abstract

Gold catalysts have attracted attention for enabling sustainable chemical processes under ambient conditions. This reactivity is attributed to the small size of the catalysts (<5 nm); however, their size also creates difficulty when removing from product streams and often require rare-metal additives to enhance reaction rate kinetics, thereby limiting the environmental benefits of these catalysts. Comparatively, submicron gold catalysts are easier to separate but are much less reactive under ambient conditions. In this study, we synthesized submicron gas-stabilising gold nanocones (gs-AuNCs) that are acoustically responsive to afford greater reaction rates than other conventional gold catalysts. We explore the catalytic performance of acoustically responsive gs-AuNCs exposed to focussed ultrasound at 5.0 MPa peak negative pressure and 1.1 MHz center frequency. Cavitation nucleated from gs-AuNCs significantly increased the sonocatalytic degradation of water pollutants without the need for co-catalysts. The ability to amplify catalysis with ultrasound by tailoring the morphology of the catalyst to control cavitation opens new paths for future designs of sonocatalysts that may enable a sustainable chemical approach needed for a broad range of industrial processes.

Keywords

Gold nanoparticles
Gold catalyst
Ultrasound
Cavitation
4-nitrophenol

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