Molecular exploration of supported sulfide and oxysulfide nano-structures for the photocatalytic reduction of CO2

Within the context of CO2 emissions abatement, "Solar Fuels" production, i.e. energy carriers using sunlight as primary energy source, represents an appealing but challenging alternative. Inspired by natural photosynthesis, this alternative aims at storing solar energy in chemical bonds by achieving CO2 photo-reduction into valuable compounds. This way of producing synthetic fuels would be neutral in terms of carbon footprint and would make this process a clean and renewable fuel production process.
Nevertheless, conversion reactions of photonic energy into chemical energy by photocatalysis suffer from far too low yields. The major challenge remains therefore to develop and optimize efficient catalytic materials that photo-reduce CO2 with largely increased quantum yields and overall efficiency.
The general objective of this PhD thesis is to develop via a molecular approach a new class of molybdenum oxy-sulfide materials exhibiting the proper semiconducting and reactive properties. With those materials, we aim at enhancing global solar conversion performances by absorbing photons of visible wavelengths and by limiting electron-hole carriers recombination. 
The objective of this work will be to understand the relationship between heterostructure and reactivity of these materials. Synthesis methods from soft chemistry will be developed and optimized in order to control the nature of the molybdenum oxy-sulfide phases, its interface with the support and its nanoscale dimensionality (0D-cluster, 1D-ribbon, 2D-layer, 3D multi-layers…). The synthesized materials will be finely characterized in order to determine their elementary composition, their nano-structure and their opto-electronic properties. The bandgap widths will be evaluated using UV-Visible characterization and will be compared with ongoing quantum calculations carried out on similar systems. Reactivity will be measured on the CO2 photoconversion unit at IFPEN, which will be able to carry out parametric studies in terms of CO2 and H2O flow, irradiance, wavelength range, temperature, and possibly pressure. The test conditions will be representative of those of a plugged process at the exit of plant chimneys.
The thesis will predominantly take place at the IFPEN of Solaize and in close collaboration with ETH Zürich, to allow the student to carry out dedicated synthesis during some stays.

Keywords: Photocatalysis, solar fuel, metal sulfides, semiconductors, CO2, solar energy.

• IFPEN supervisors    Dr. Pascal Raybaud and Audrey Bonduelle, Catalysis, Biocatalysis and Separation Division (Solaize, France) : audrey.bonduelle@ifpen.fr
• https://www.ifpenergiesnouvelles.fr/page/audrey-bonduelle  https://www.ifpenergiesnouvelles.fr/page/pascal-raybaud
• Academic supervisors    Prof. Dr. Christophe Copéret and Victor Mougel, ETH Zürich (Switzerland) https://coperetgroup.ethz.ch/  https://mougel.ethz.ch/
• Doctoral School    ED 206 - Chimie Lyon 
• PhD location    IFP Energies nouvelles, Lyon, France  
• Duration and start date    3 years, starting preferably on November 1, 2021
• Employer    IFPEN, Rueil Malmaison, France
• Academic requirements    Master degree in catalysis or inorganic chemistry
• Language requirements    Fluent in English and French, or willingness to learn French