Water-splitting on thin film hematite electrodes with Ruthenium dioxide nanoparticles
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Sähkötekniikan korkeakoulu |
Master's thesis
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Authors
Date
2021-05-17
Department
Major/Subject
Photonics and Nanotechnology
Mcode
ELEC3052
Degree programme
Master’s Programme in Electronics and Nanotechnology (TS2013)
Language
en
Pages
50+7
Series
Abstract
The Photoelectrochemical (PEC) water-splitting process can decompose water into hydrogen and oxygen with photocatalyst and solar energy. Hematite is a promising photocatalyst with abundant reserves, low costs, chemical stability, and appropriate bandgap. In the PEC water-splitting process, hematite can achieve the water-splitting process by moving the photogenerated charges to the electrolyte solution. Ruthenium dioxide is a potential co-catalyst that can accelerate this transporting process. The thesis aims to improve the water-splitting performance of hematite with the help of photo-deposition of Ruthenium dioxide nanoparticles and understand the effects of different photodeposition variables. In the experimental section, evaporated 10nm thick iron was baked to hematite in an oxygen atmosphere for different times to study Indium doping's influence. The samples were then photodeposited with Ruthenium nanoparticles with different recipes of precursors solution and exposing time. RAMAN, EDX, AFM, and SEM measurements are executed to analyze the sample element components and sample surface morphology. A basic PEC cell was constructed to execute linear sweep voltammetry and electrochemical impedance spectroscopy measurements. The obtained results show that with the photodeposited Ruthenium dioxide, the highest current density of the samples was three times larger than the bare hematite at 1.23V, which was a significant improvement. The onset potential was found to be shifted from 1.0V to 0.8V, and there also appeared a small peak at around 0.5V due to the Ruthenium dioxide nanoparticles. The results also show that methanol concentration indeed influenced the shape and distribution of Ruthenium dioxide nanoparticles. One concern in the experiment is the instability of Ruthenium dioxide nanoparticles, thus in the future, potential steps, such as annealing and applying other co-catalyst on the top, can be applied to improve its electrochemistry stability. Furthermore, the assembly methods of the photoelectrode could be improved to reduce the number of failed samples.Description
Supervisor
Tittonen, IlkkaThesis advisor
Tossi, CamillaKeywords
PEC water-splitting, photodeposition, hematite, RuO2 nanoparticles