DISSERTATION ENGINEERING PHTHALOCYANINES AND CARBON COMPOSITES FOR USE IN SENSING, MICROFLUIDICS AND DYE SENSITIZED SOLAR CELLS Submitted by Kevin Jay Klunder Department of Chemistry In partial fulfillment of the requirements For the Degree of Doctor of Philosophy Colorado State University Fort Collins, Colorado Summer 2018 Doctoral Committee: Advisor: Charles Henry Amy Prieto Melissa Reynolds George Barisas Shantanu Jathar Copyright by Kevin Jay Klunder 2018 All Rights Reserved ABSTRACT ENGINEERING PHTHALOCYANINES AND CARBON COMPOSITES FOR USE IN SENSING, MICROFLUIDICS AND DYE SENSITIZED SOLAR CELLS The focus of this thesis is on fundamental and applied electrochemistry in the areas of photovoltaics, sensors, and microfluidics. Photovoltaics are important as they are needed to reduce the amount of greenhouse gases, pollution, and reliance on finite energy sources that are currently associated with energy production. A thin film photovoltaic device known as a dye sensitized solar cell (DSSC) is studied in his work. Specifically the cathode of the DSSC is studied in detail. A new method to create a highly transparent and catalytic DSSC cathode coating is proposed. The phthalocyanine based coatings have ~97% transmittance at 550 nm and low charge transfer resistance of ~1.3 Ω cm2, representing one of the best cathode coatings in terms of transparency and charge transfer resistance to date. Electrochemical sensors and electrochemical microfluidics can be used to monitor air, water and soil pollution, both of which can occur from anthropogenic and/or natural sources. Quantifying this pollution is vital for human and animal safety. Electrochemical sensors are also used for health diagnostics and are commonly applied in blood glucose monitoring. It is projected that wearable forms of electrochemical sensors will emerge as a vital class of real-time point-of-care sensors to monitor health indicators in the near future. To advance the field of electrochemical sensors and electrochemical microfluidics low cost, easily miniaturized, patterned, and shaped electrodes are needed. The work here ii introduces a new fabrication method for carbon composites which enables electrodes to be patterned and made into micron features in a facile manor through solvent or melt processing. The composites are also shown to be easily integrated into microfluidic devices, demonstrated with the assembly of electrochemical droplet microfluidics. The ease of fabrication of the new composites represents a milestone for the widespread use of low cost carbon composites in complex electrochemical systems. Within this thesis, Raman, SEM, XRF, and a wide range of electrochemical redox species and techniques are used to determine what factors affect the electrochemical activity, capacitance, and conductivity of the carbon composites. Finally, phthalocyanines for uses in electrochemical catalysis are a recurring theme throughout the thesis. Chapter 4 is dedicated to creating new types of electropolymerizable phthalocyanines. Cobalt phthalocyanine is integrated into the carbon composites from Chapter 2 for uses in thiol oxidation and the sensing of thiols. The thiol of interest was dithiothreitol (DTT) which is used in the “DTT assay”. The DTT assay is a chemical measure of oxidative potential of particulate matter, and is commonly used to try and understand health effects relating to air pollution. Here, low volume disposable cells, as well as flow based sensors are developed for the detection of DTT. iii ACKNOWLEDGMENTS I would like to thank my parents, as well as my academic parents for all of their many contributions to my success. I would like to thank the chemistry professors at GRCC, Dr. Niels, William Faber, and Jennifer Batten for the time and energy they invested in me. Jennifer’s organic class was a main reason I chose chemistry as a major. I am also grateful for the energetic atmosphere within the chemistry department at Hope College and my undergraduate advisors Graham Peaslee, Ken Brown, as well as Fred Heckman (Tennent). I must also acknowledge the MSU Bioeconomy institute and Tom Guarr for letting me run loose in the lab and providing me with a highly rewarding research experience. I would like to acknowledge Mike Elliott. Upon meeting Mike initially I was attracted to his passion for science, no BS attitude, and general saltiness. He is a main reason why I came to CSU and my first year working side by side with him in the lab was something I will always remember. I would like to thank Rick Finke and the members of the Finke group. Rick and the group helped immensely throughout my graduate school progression. Finally, I would like to thank Charles Henry, who has broadened my education in a number of unique ways. Chuck has been a cheerleader for my research, even when I didn’t think it is all that good. Despite his crazy schedule he still managed to be actively involved in my work, was responsive and engaged, and for this I am grateful. iv TABLE OF CONTENTS Abstract ............................................................................................................................................................................. ii Acknowledgments ....................................................................................................................................................... iv Chapter 1: INTRODUCTION ..................................................................................................................................... 1 Chapter 2: DEVELOPMENT AND CHARACTERIZATION OF THERMOPLASTIC CARBON COMPOSITE ELECTRODES ...................................................................................................................................... 5 2.1 Introduction .............................................................................................................................................. 5 Overview ............................................................................................................................................. 5 Background on graphite and its electrochemistry ......................................................... 5 Background on carbon composite electrodes ................................................................... 8 2.2 Results and Discussion ..................................................................................................................... 11 Fabrication, Templating, and Patterning of ThermoPlastic Electrodes (TPE)11 Conductivity measurements................................................................................................... 13 Electrochemical characterization of TPE ......................................................................... 16 Capacitance of TPE ...................................................................................................................... 17 Comparison to commercial electrodes .............................................................................. 19 Surface insensitive probe ......................................................................................................... 21 Oxide sensitive probe ................................................................................................................ 22 Surface sensitive probe ............................................................................................................. 24 Surface adsorption dependent .............................................................................................. 25 SEM characterization of TPE surface treatment ........................................................... 26 Raman characterization of TPE............................................................................................. 28 Investigation into electrochemical reactivity of some commercial carbons .. 33 Solvent window of TPE electrodes in acid and base ................................................... 36 Metal and oxide sensitive redox probes ........................................................................... 45 2.3 Conclusion and Future Work ......................................................................................................... 49 v Overview .......................................................................................................................................... 49 Future work .................................................................................................................................... 50 2.4 Materials and Methods ..................................................................................................................... 53 Reagents ........................................................................................................................................... 53 Fabrication of TPE-Step 1 Electrode Fabrication-Solution Preparation ........... 53 Fabrication of TPE-Step 2 Electrode Fabrication- Templating characterization .................................................................................................. 54 Conductivity measurements................................................................................................... 55 Electrochemical measurements and surface treatment ........................................... 56 Capacitance Measurements .................................................................................................... 57 Spectroscopy .................................................................................................................................