Photoelectrochemical Studies on a Triad Electrode for Light-driven Water-splitting Open Access

Abstract

A photoelectrochemical device is highly desirable for solar to chemical fuel (in our study H2 is the fuel) conversion. An essential component of such device is the photoanode which absorbs light and catalytically oxidizes water. Here we report a method of fabricating a photoanode by immobilizing a known homogeneous molecular water oxidation catalyst, [Ru^IV4O4(OH)2(H2O)4}(γ-SiW10O36)2]¹⁰-, onto a dye-sensitized nanostructured TiO2 photoelectrode by electrostatic interaction. The known sensitizers [Ru(bpy)2(4,4'-PO3H2bpy)]²⁺ (P2) and its modified version [Ru(5-crown-phen)2(dpb)]²⁺, dpb =4,4'-diphosphonic acid 2,2'bipyridine (C2P2) were both used. The polyoxometalate catalyst with different cations (inorganic and organic cations) was used. The effect of sensitizers and catalysts on photoelectrochemical properties were compared and discussed. An enhanced photocurrent is observed with the triad photoanode FTO/TiO2/P2/THpA-Ru4POM with an applied bias of 500mV and FTO/TiO2/C2P2/THpA-Ru4POM with no external bias. The bias-dependent behaviors of the photocurrent are in good agreement with calculated frontier orbitals.

Table of Contents

Table of Contents
Abstract...iv
Acknowledgement...v
List of Abbreviations...viii
List of Figures...ix
List of Schemes...x
Chapter 1 Introduction...1

1.1 General Introduction...2
1.2 Light-driven Water-splitting...3
1.3 Photoelectrochemical Cells...5
1.4 Sensitizers...9
1.4 POM WOCs...15

Chapter 2 Experimental Section: Preparation of Electrodes, Investigation of the Stability and Photoelecrochemical Performance...19

2.1 Material and Preparation...21

2.1.1 Preparation of TiO2 colloid and film...21
2.1.2 Sensitizers Used in This Work...21
2.1.3 WOCs Used in This Work...22

2.2 Electrode Assembly...23

2.2.1 Dyad Electrode...23
2.2.2 Triad Electrode...23

2.3 UV-Vis spectroscopic Measurements...24
2.4 Photoelectrochemical Measurements...25

Chapter 3 Results and Discussion...28

3.1 Electrode with P2 as Sensitizer...29

3.1.1 UV-Vis Spectra and Stability...30
3.1.2 Photoelectrochemical Measurements...33

3.2 Electrode with C2P2 as sensitizer...39

3.2.1 UV-Vis spectra and Stability...39
3.2.2 Photoelectrochemical Measurements...43

Chapter 4 Summary...48
References...50

About this Master's Thesis

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School	Laney Graduate School
Department	Chemistry
Degree	MS
Submission	Master's Thesis
Language	English
Research Field	Chemistry, Inorganic
Keyword	photoelectrochemical water-oxidation catalyst polyoxometalate
Committee Chair / Thesis Advisor	Hill, Craig L, Emory University
Committee Members	Lian, Tim, Emory University MacBeth, Cora, Emory University

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