15 May 2017

9. 2. 2017 | Susan

Anton Litke MSc
Transition metal sulfides and oxides: synthesis, energy conversion application, and charge carrier dynamics
Promotores: Prof. E. Hensen, Prof. T. Weber, Dr. J.P. Hofmann (Eindhoven University of Technology)

Summary of thesis
The main focus of the work was on gaining understanding of photocatalytic materials synthesis, parameters limiting their performance, and dynamics of photogenerated charge carriers. The systems studied are mixed Cd-Zn sulfides, titania and combinations thereof. The work can be divided into two main parts.
The first part deals with synthesis, characterization, and testing of transition metals sulfide-based materials in the visible-light driven water reduction reaction. This section explores hydrothermal synthesis of mixed Cd-Zn sulfides and their composites with TiO2.

The highlights of this work include:
Formation mechanism of mixed Cd-Zn sulfides from mixtures of insoluble Cd and Zn hydroxides under hydrothermal conditions was elucidated.
The effect of nano-twinned particles present in sulfide samples on their apparent activity was resolved.
Analysis of the crystal phase composition of mixed Cd-Zn sulfides revealed the presence of compositional inhomogeneities.
Composite materials based on highly active Cd-Zn sulfides and commercial TiO2 were explored for visible light-driven reduction of water. Electron transport in oxide particles was found to limiting performance of these materials.

The second part is devoted to investigation of charge carriers dynamics in photocatalytic materials under model conditions by steady-state and time-resolved FTIR spectroscopy. Highlights include:
Influence of adsorbed water on dynamics of photogenerated charge carriers in P25 TiO2 photocatalysts at subsecond to minutes time scale.
Investigation of shallow trapped electrons formation in TiO2–based materials.
Interaction of photogenerated charge carriers with probe molecules adsorbed on TiO2-supported Pt nanoparticles.