Nanoparticle stochastic impacts at hard & soft interfaces, supported in an ionic liquid

Ahmadinasab, Nazanin (2022) Nanoparticle stochastic impacts at hard & soft interfaces, supported in an ionic liquid. Masters thesis, Memorial University of Newfoundland.

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Abstract

Over the past 20 years, nanoparticle (NP) investigations by single entity electrochemistry (SEE) have become increasingly popular owing to simultaneous acquisition of both catalytic and dynamic NP information. Typically, NPs travel through solution under Brownian motion. When metal NPs randomly collide with an ultramicroelectrode (UME) they can usually be detected through either of two charge transfer processes: (i) complete oxidation of the NP or (ii) electrocatalytic amplification (ECA). In the latter, the metal NP acts as a catalytic surface lowering the driving force of reaction (i.e., necessary applied potential), greatly enhancing the measured current signal. Owing to their random motion, NPs impact the surface and then move way or are consumed which generates a ‘current spike’ with a characteristic profile in the recorded chronoamperogram (i-t curve). Herein, Pt and LiBH₄ nanocrystals (NCs) prepared in trihexyltetradecylphosphonium bis(trifluoromethylsulphonyl)imide (P₆₆₆₁₄NTf₂), an ionic liquid (IL), were studied at both solid/IL (UME) and soft (water|IL) micro-interfaces. Pt NPs showed electrocatalytic activity for borohydride oxidation reaction (BOR) and methanol oxidation reaction (MOR) through ECA. Also, this method was used for calculating the size of LiBH₄ dielectric nanocrystals (NCs) by integrating the i-t curve beneath the current spikes, which compared favourably to NP sizes determined from TEM micrographs.

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