Applications of Bipolar Electrochemistry for Characterization of Electrocatalysts and the Development of Biosensors

Abstract

Bipolar electrochemistry, which is an untraditional technique where redox reaction happens on the surface of a conducting object (BPE) that immersed in an electrolyte solution wirelessly connected with an external power source, has attracted great interest over last decades and used in a variety of fields. This dissertation work, which used bipolar electrochemistry as a basic platform, focuses on electrodeposition of bimetallic materials and its electrocatalysis on molecules, refinements of BPE setup on electrochemical cell, and biosensing.

Chapter 1 presents a detailed literature review on the background and operational principle of bipolar electrochemistry and ECL (electrochemiluminescence), and its applications on the fields of materials science and dynamic systems, sensing and screening, also, the current stage of research is detailly discussed. Moreover, a brief introduction on diabetes, especially on glucose detection based on bipolar electrochemistry platform.

Chapter 2 describes an experimental approach for adapting the principles of Raman Spectro-electrochemistry to electrodes controlled using a bipolar circuit, which allows the simultaneous acquisition of spectroscopic data as a function of both the electrode potential and the chemical composition of a bimetallic alloy and can be generalized to other system variables. The electrochemical reduction of 4-nitrothiophenol (4-NTP) was carried out on bimetallic Ag/Au alloy gradients and monitored in situ using a confocal Raman microscope with 785 nm excitation.

Chapter 3 illustrates the potential profiles from open cell frame, closed cell frame, and channel cell frame. And four models from channel cell frames were offered to describe and explain the channel potential based on the variables of normalized channel length and width. Most importantly, this work may give some guideline to some researchers to the determination of what kind of cell frames to choose, what kind of details to be aware of for different cell frames, and what is the optimal cell frame design for the BPE system.

Chapter 4 reports a new glucose biosensor platform based on cathodic ECL in a closed BPE system. In this C-ECL-C-BPE (cathodic ECL in a close BPE cell) glucose biosensor, 𝑅𝑢(𝑏𝑝𝑦)32+ (tris(2,2’-bipyridyl) ruthenium) used as luminophore and K2S2O8 used as co-reagent to generate the cathodic ECL signal; two GCEs (glassy carbon electrodes), one acts as BPE cathode and the other acts as driving anode, used in the reporting cell; and a commercial test strip that already modified GOx (glucose oxidase) and mediator used in the sensing cell. Under a certain applied DC voltage, a higher current would produce when glucose concentration varied from low to high, which need reduce more 𝑅𝑢(𝑏𝑝𝑦)32+ and persulfate to compensate for it and result in a more incensed ECL signal, using this mechanism, glucose detection could be achieved. Moreover, a comparison between proposed C-ECL-C-BPE glucose biosensor and commercial blood glucose meter was performed for determination of glucose in human serum samples.

Chapter 5 summarizes the research contribution of this dissertation, and a briefly statement of recommended future work of these projects.