The electrochemistry of 2d hexagonal boron nitride

Khan, Aamar Farooq (2018) The electrochemistry of 2d hexagonal boron nitride. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Since the discovery of the unique physical properties of graphene, research has intensified in the field of two-dimensional (2D) nanomaterial electrochemistry. Indeed, newly emerging 2D materials such as 2D-hexagonal boron nitride (2D-hBN) have the potential to transform the field of electrochemistry when implemented as a next generation electrode material. This thesis reports on the electrochemical applicability of utilising 2D-hBN, previously considered non-electroactive, as a novel electrode material. Also considered is the effect of the fabrication process of 2D-hBN when employed towards a range of electrochemical applications. Chapter 1 gives an overview of the general electrochemical concepts that concern this thesis. Chapter 2 offers an insight into recent 2D materials electrochemistry literature regarding, first, graphene and then 2D-hBN. From this, successive chapters follow the development and investigation of 2D-hBN, formed via differing synthesis techniques, thus enabling a truer reflection of 2D-hBN as an electrode material to be achieved. Chapter 3 details the relevant experimental information and the full physicochemical characterisation of the different 2D-hBN materials employed within this thesis. Chapters 4 and 5 utilise surfactant-free (pristine) 2D-hBN, where pristine 2D-hBN is ‘electrically wired’ upon a suitable electrode surface. Chapter 4 reveals for the first time that pristine 2D-hBN gives rise to beneficial electrochemical behaviour towards the oxygen reduction reaction (ORR) when immobilised upon a graphitic substrate. Chapter 5 explores pristine 2D-hBN towards a biological approach in the sensing of dopamine (DA) and its common interferents ascorbic acid (AA) and uric acid (UA). Pristine 2D-hBN exhibits a beneficial electrocatalytic effect towards the detection of dopamine when immobilised upon a graphitic substrate. This observed beneficial effect upon the utilisation of pristine 2D-hBN has not previously been reported in the literature when supported upon any electrode. Both chapters implement ‘mass coverage’ studies of 2D-hBN, an often overlooked parameter within the literature Chapters 6 and 7 utilise surfactant-exfoliated 2D-hBN and compare the effect of the fabrication process of 2D-hBN (pristine vs. surfactant-exfoliated) upon the observed electrochemistry towards the ORR, capacitance applications and the sensing of dopamine, via a dropcasting electrode modification approach. Chapter 6 explores surfactant-exfoliated 2D-hBN towards the ORR and capacitance applications for the first time. The surfactant-exfoliated 2D-hBN nanosheets are immobilised upon graphitic screen-printed electrodes (SPEs) with ‘mass coverage’ studies performed and the observed electrochemical response is compared to the surfactant-free pristine 2D-hBN approach. Chapter 7 explores surfactant-exfoliated 2D-hBN as a potential electrochemical sensing platform towards the electroanalytical sensing of dopamine (DA) in the presence of the common interferents, ascorbic acid (AA) and uric acid (UA) for the first time. Surfactant exfoliated 2D-hBN is electrically wired via a drop-casting modification process onto SPEs and the observed electrochemical response is compared to the surfactant-free (pristine) 2D-hBN approach. The performance of these surfactant-exfoliated 2D-hBN modified SPEs are critically evaluated upon the implementation of ‘mass coverage studies. Chapter 8 explores for the first time a low cost and reproducible approach for producing 2D Hexagonal Boron Nitride (2D-hBN) electrochemical screen-printed platforms (hBN-SPEs). These novel hBN-SPEs are explored as a potential electrocatalyst towards the ORR. This fabrication approach is compared to the drop casting technique of pristine and surfactant-exfoliated 2D-hBN utilised towards the ORR, thus offering an alternative approach. This thesis demonstrates for the first time that 2D-hBN is electroactive when immobilised upon a graphitic substrate towards a range of applications. It is also shown that fabrication process in the production of 2D-hBN can affect the observed electrochemistry, thus control experiments must be undertaken to truly understand the impact of this material.