Chemistry

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3 April 2019

Research Seminar: Photoelectrochemistry and Electrocatalysis at the Interface between Two Immiscible Electrolyte Solutions

Presented By Dr Micheál Scanlon (University of Limerick)

About this event

Special seminar within the RSC Midlands Electrochemistry Group Meeting

Abstract

Liquid-liquid interfaces are emerging as powerful, transparent, defect-free platforms for bottom-up fabrication of ordered two-dimensional (2D) and three-dimensional (3D) assemblies of molecular species and nanoparticle (NP) arrays [1]. The fluidic nature of these interfaces allows them to self-heal, permitting the preparation of robust assemblies of remarkable uniformity at room temperature extending over large geometric areas (at least cm2) without the use of specialised equipment [1].

Certain soft interfaces formed between aqueous and organic electrolyte solutions of low miscibility (e.g.,trifluorotoluene) are electrochemically active in the sense that it is possible to precisely control the Galvani potential difference between the two adjacent liquids (i.e.,to “polarise” or electrify the interface), and thus drive charge transfer reactions [2]. Such interfaces are denoted interfaces between two immiscible electrolyte solutions (ITIES). The ITIES can be controllably electrified by application of a potential externally through the use of electrodes immersed in both phases. The potential drop spans the interface and is termed the Galvani potential difference; it can be manipulated to provide a polarisable potential window as wide as ∼1.0 V.

In this presentation, I will discuss methods to dye-sensitise a liquid-liquid interface with porphyrin nanostructures, and use these dye-sensitised electroactive “soft” interfaces to achieve solar energy conversion. I will highlight that techniques used to characterise traditional solar cells, such as photocurrent transient and intensity modulated photocurrent spectroscopy (IMPS) measurements, are equally applicable at the ITIES. I will also discuss methods to form films of gold nanoparticles at the ITIES, and demonstrate their electrocatalytic activity and future applicability to form unique sensors based on surface enhanced Raman spectroscopy (SERS).

References:

[1]       M.D. Scanlon, et al., Chem. Rev.118(2018) 3722.
[2]       Z. Samec, Pure Appl. Chem.74 (2004) 2147.