Electrochemical Behaviour of Microporous Materials for Water Purification

Abstract

Ionic current rectification describes the unique electrochemical behaviour for
devices based on microporous materials to conduct ions only in one direction under
applied potential bias. The mechanism of ionic current rectification for all types of
microporous materials are similar and based on electrolyte accumulation (open
diode) and depletion (closed diode) within the region of a microhole in the substrate.
The ionic current rectification phenomenon has been investigated for different types
of ion conducting microporous materials with applications linked to future water
desalination technology. In general, there are three types of microporous materials
studied in the thesis that have been investigated based on (i) one-dimensional, (ii) two-dimensional, and (iii) three-dimensional pore systems. All of these microporous materials show good performance as long as semi-permeability can be achieved and maintained.

In this thesis, ionic current rectification phenomena have been studied and
investigated for different types of microporous materials such as, bacteriophage M13 (one-dimensional), graphene oxide and titanate nanosheets (two-dimensional), and Nafion and PIM-EA-TB “heterojunction” (three-dimensional). Each of these microporous materials gives unique electrochemical characteristics (ionic current rectification phenomena) when deposited as a film onto a poly-ethylene-terephthalate (PET) susbtrate with 20 μm diameter microhole. In the final chapter of this thesis, it is demonstrated a water desalination prototype based on ionic current rectification in microporous materials. It can be concluded that ionic diode devices based on different types of microporous materials provide a new avenue of fundamental electrochemical study with effects based on materials, device geometry, and electrolyte media. In the future, there is a possibility to develop ionic circuits and a wider range of ionic devices to provide new types of interfaces between artificial electronic systems and biological ionic systems.

Date of Award	4 Nov 2020
Original language	English
Awarding Institution	University of Bath
Supervisor	Frank Marken (Supervisor) & Janet Scott (Supervisor)