Exploiting the instability of capped metal nanoparticles on metallic surfaces

Awais, Nashwa (2020). Exploiting the instability of capped metal nanoparticles on metallic surfaces. University of Birmingham. M.Sc.

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Abstract

Small metal nanoparticles (NPs) within the size range of 1-3 nm exhibit unique electronic and catalytic properties. Thiolated nanoparticles have been shown to undergo an at least partly entropically driven redistribution of the capping layer when AuNPs are exposed to bare Au substrates. It has been postulated that different substrate and NP materials may be employed for surface design, as the interaction between the protected nanoparticles with the metal substrate could aid in the removal of the thiol layer.

The aim of this work was to investigate outcomes of surface structure modification for different substrate-NP combinations, in alkaline media and via their performance in the electro-catalytic decomposition of glycerol (GlyOH). Pt surface/AuNP and Au surface/PtNP combinations were investigated, by immersion of the surfaces into solutions of the NPs.

Au NPs were synthesised using a bottom-up metal reduction, and Pt NPs were synthesised via the cathodic corrosion method. Electrochemical responses were measured using cyclic voltammetry (CV). Addition of the Au NPs to the Pt surface resulted in a lower current response, but no change in characteristic Pt peaks within the CV profile, nor emergence of Au related features, indicate that the Au NPs remain protected on the surface. However, addition of the Pt NPs to the Au surface resulted in a notable change in the CV profile, to include both Au and Pt characteristic peaks. In particular, the effect of modifying the Au surface with PtNPs was significant, in that the characteristic peak corresponding to the electro-oxidation of GlyOH by Pt became visible. These findings are in line with a potential thiol redistribution effect, as shown for the Au surface/AuNP system, although further investigation into the surface dynamics of the nanoparticles on the surface may be required.

Type of Work:

Thesis (Masters by Research > M.Sc.)

Award Type:

Masters by Research > M.Sc.

Supervisor(s):