Author ORCID Identifier

https://orcid.org/0000-0002-5371-0175

Year of Publication

2020

Degree Name

Master of Science in Chemical Engineering (MSChE)

Document Type

Master's Thesis

College

Engineering

Department

Chemical and Materials Engineering

First Advisor

Dr. Stephen Rankin

Second Advisor

Dr. Barbara Knutson

Abstract

Sensitization of mesoporous titania films with dopamine and polydopamine for visible light photoelectrochemical activity is investigated. Sensitization effectiveness is compared with 8 mM dopamine solutions of varying pH (acidic, basic, and neutral), as well as with a basic polydopamine solution. Vibrational changes due to dopamine attachment are determined from detached powders by Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) is used to quantify organics attached. X-ray photoelectron spectroscopy (XPS) of intact films probes the chemically induced charge shift from dopamine attachment. Cyclic voltammetry identifies the irreversible dopamine oxidation and tin reduction voltages. Finally, chronoamperometric curves are used to compare the photoelectrochemical water splitting performance of samples sensitized in different environments. FTIR results indicate mainly bidentate attachment of dopamine to titania, with minor monodentate attachment. XPS and TGA indicate quick saturation of the surface during sensitization, most notably for polydopamine, and XPS indicates a range of charge shifts from 2.28 eV to 2.83 eV for oxygen and titanium binding energies. Dopamine sensitization in DI water for 15 minutes gave optimal water oxidation, enhanced by 80 times (under 455 nm light and 0.4 V) compared to pure titania films. Preliminary photocatalytic water reduction using dopamine-sensitized titania films are investigated.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.163

Funding Information

All experiments were performed as part of National Science Foundation EPSCoR research infrastructure award (grant no. IIA-1355438) (2017-2019) and grant no. CBET-1604491 (2019-2020). The XPS characterization was performed through access to characterization instruments and staff assistance provided by the Electron Microscopy Center at the University of Kentucky, supported in part by the National Science Foundation/EPSCoR Award No. 1355438 and by the Commonwealth of Kentucky.

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