Enhanced catalytic performance through precise structural modification of Au-Ag nanoworms using controlled etching process

Date

2025-05-20

Author

Khan, Ghazanfar Ali
Bek, Alpan
Masson, Jean-Francois
Ahmed, Waqqar

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Polycrystalline nanomaterials inherently possess a high concentration of defects, owing to the presence of grain boundaries. These defects, while abundant in smaller nanoparticles (NPs), can become embedded within the bulk of larger particles, making them inaccessible to reactants during catalytic reactions. While deliberately arresting growth at the initial stage can reveal defect sites resulting in particles with significantly high surface energy, the precise control required to halt the growth of nanomaterials at the specific moment of optimal catalytic potential poses a formidable challenge. Herein, we introduce an alternative approach that involves the oxidative etching of fully developed polycrystalline Au-Ag alloy nanoworms (NWs). This process generates high-energy surfaces rich in defects, thereby substantially enhancing their catalytic activity. The NWs were synthesized by a seedless, single-step method and they were subsequently etched by using HAuCl4 solution. The elaborate process underlying the transformation of NWs’ structures upon exposure to HAuCl4 solution was elucidated. The Transmission Electron Microscopy (TEM) images showed a gradual decrease in the length and width of NWs and an increase in the defect density with etching. Remarkably, small alterations in the NWs’ morphology led to marked enhancement in their catalytic activity. To demonstrate this, NWs were employed for catalyzing the conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The optimized etching of NWs provided an approximately 24-fold enhancement in the activity compared to the unmodified NWs. The implications drawn from our results strongly imply that the structural modifications introduced by the etching process can be an effective technique for enhancing the catalytic activity of polycrystalline NPs.

Subject Keywords

4-nitrophenol, Galvanic replacement reaction (GRR), Gold nanoparticles, Heterogeneous catalysis, Surface defects, Surface modification

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https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85218450496&origin=inward
https://hdl.handle.net/11511/113992

Collections

Department of Physics, Article