|M.Sc Student||Neufeld Ofer|
|Subject||A Theoretical Study of ALFA-Fe2o3; Solar Water Splitting|
Catalysis and Metal/Metal-Oxide Interfaces in
Advanced Photoelectrochemical Cells
|Department||Department of Energy||Supervisor||Professor Maytal Caspary-Toroker|
|Full Thesis text|
Many challenges face mankind in the upcoming decades, the most important of these is the world energy crisis. A cheap, renewable, and clean energy source is required to keep up with the world population increase while attempting to maintain the current standard of living. A promising solution is using solar radiation as a source of renewable energy. Unfortunately, although the sun radiates abundant and huge amounts of energy to the planet's surface, it does not shine on earth at night. Therefore, a way to store solar energy for night time use is needed. We explore strategies of improvement in photoelectrochemical (PEC) cells, which are designed to store solar energy in the chemical bond of hydrogen gas through splitting water molecules.
In this work we use computational methods in a quantum mechanical formalism to understand the physical processes governing PEC cells and consequently attempt to predict new architectures for better photocatalysts. We use ab-initio methods based on density functional theory (DFT) and other variations such as DFT and GW, as well wave packet propagation methods for solving the time-dependent Schrödinger equation.
In particular, this study focuses on processes involving iron(III) oxide photoanodes that are commonly used in PEC cells. We consider different regimes of the photoanodes: bulk, surface, and interface with a metal. We suggest different strategies of improving efficiencies of PEC cells and designing new and improved photocatalysts, such as: an ideal Pt doping concentration in the bulk of iron(III) oxide for improved electron conductivity, gradient doping in the bulk oxide to avoid an increase in the overpotential, partially coating the surface with an oxide layer with a smaller work function than that of iron(III) oxide to lower the overpotential, and using a metal back contact against the iron(III) oxide to increase charge separation in the oxide. Additionally, we lay ground work for a high throughput screening method for metal/oxide junctions for optimizing charge transport across the interface. The method is characterized and demonstrated in the metal/oxide system for various choices of face-centered cubic metals.
Finally, we suggest future PEC cells should be built by integration of all of our suggested strategies in order to get the best possible efficiencies.