DS0305 -

Oxysulfide and Oxynitride Nanomaterials for Electrocatalysis – OxySUN

Submission summary

Oxysulfides (MxOySz) and oxynitrides (MxOyNz) represent two families of materials that have scarcely been studied, in comparison with oxides, even though they show potentially exciting properties for the fields of energy storage, optics and catalysis. Their band-gap can be tuned in a wide range that goes from semi-conductor to metal, and their electronic properties such as conductivity, vary with the composition. Because they are more covalent than metal oxides and, in contrast to metals, they are not easily oxidized, they have been identified as very promising phases for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) that are typically performed in a corrosive medium. The source of electron may come from light (photocatalysis) especially for phases that absorb visible light, or from a generator (electro-catalysis), depending on the band structure.

In order to benefit the full potential of oxynitrides and oxysulfides, they should be prepared as size-controlled nanoparticles. This is a very challenging objective: these phases are typically prepared using high-temperature solid-state chemistry routes, however, these routes also favor grain growth, preventing the fabrication of nanoparticles. Beyond this, chemical pathways that provide a strong input of energy tend to form the most stable phases, i.e. for most transition metals, nitrates and sulfates, instead of oxynitrides and oxysulfides.

In OxySUN, we will address this challenge by proposing an unprecedented solution route to reach nanoparticles of well-controlled size, composition and band-gap. It will consist in using highly reactive metal and heteroelement (S, N) precursors, manipulated under inert atmosphere, hence allowing for a precise control of the stoichiometry of all elements involved. This proposition is in line with the project coordinator own expertise in molecular and organometallic chemistry.

We will focus on molybdenum-containing phases, because of the very interesting properties of this metal in electro- and photo-catalysis. Molybdenum is versatile in terms of oxidation states and accessible local structures, which will maximize our chances to produce nanoparticles of known macroscopic molybdenum oxysulfide phases, but also to form new phases of oxysulfides and oxynitrides.

We will also explore bi-cationic phases containing Co, Fe, or Ni. These three metals were selected because of their low cost and high interest for electro-chemical and photo-chemical processes. The bi-cationic compounds will expand the range of accessible structure and provide an opportunity for exploring an alternative synthetic route, starting from alloyed nanoparticles. It will also allow tuning the electronic properties of the final compounds.

Composite electrodes will be prepared with the nanoparticles. Their structure will be optimized by conductivity measurement and cyclic voltammetry. Their performances in the oxygen reduction reaction will then be compared with those of reference nanoparticles (Pt and RuO2). Using two synchrotron-based spectroscopies, we will also characterize in situ the behavior of the nanoparticle’s surface in order to better understand their ageing mechanisms, which is critical to their future use in a real device.

On the middle-term, we plan to further develop this exploratory project by selecting the most promising nanoscaled phase prepared in OxySUN and optimizing its catalytic performances in collaboration with an industrial partner.

Project coordination

Sophie Carenco (Laboratoire de Chimie de la Matière Condensée de Paris)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

LCMCP Laboratoire de Chimie de la Matière Condensée de Paris

Help of the ANR 225,524 euros
Beginning and duration of the scientific project: December 2016 - 42 Months

Useful links

Explorez notre base de projets financés

 

 

ANR makes available its datasets on funded projects, click here to find more.

Sign up for the latest news:
Subscribe to our newsletter