Geo-inspired pathways towards nanoparticle-based metastable solids

Project Information

Genesis

Grant agreement ID: 864850

DOI

10.3030/864850

EC signature date 18 March 2020

Start date 1 September 2020

End date 30 November 2026

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 999 577,00

EU contribution

€ 1 999 577,00

Coordinated by

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

Periodic Reporting for period 3 - Genesis (Geo-inspired pathways towards nanoparticle-based metastable solids)

Reporting period: 2023-09-01 to 2025-02-28

Summary of the context and overall objectives of the project

The discovery of new solids is continuously needed to find ways to address the urgent challenges that our society is facing, especially environmental and energetical issues. The search for new solids is in turn intimately linked to the development of synthesis methods. In the current urge for the sustainable synthesis of materials, taking inspiration from Nature's ways to process matter appears as a virtuous approach and is the core of the GENESIS project: the pivotal idea is to expand the collection of functional inorganic solids and nanomaterials by rational exploratory synthesis inspired by nanosciences and geosciences, which set a framework of synthesis conditions prone to yield new solids. We especially focus on the conditions of formation of gem stones (molten salts and high pressures), and of basaltic rocks (extreme heating and cooling rates). We then use nanoparticles as chemical reagents. These nanometer-scale solids can engage into chemical reactions in milder conditions than those traditionally used in solid-state chemistry. Hence, we use geo-inspired conditions to trigger a new and unexplored reactivity of nanoparticles.

We apply this concept of geo-inspired syntheses to the design of rare materials combining covalent and metallic bonds, hence localized and delocalized chemical bonds at the same time. This combination can bring unique atomic charge states and environments, which can deeply impact electrocatalytic properties applied to the production of dihydrogen from water and to the valorization of carbon dioxide. Such chemical bonds are met in compounds of transition metals with elements like boron, silicon and phosphorus. Only few known solids combine such elements into ternary or quaternary solids, which hints at an unexplored landscape of new materials.

The two overall objectives are then the creation of a synthesis methodology for the vast community of inorganic materials synthesis, and the discovery of new materials.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the first half of the project, we have made advances on important fronts:

(1) Setting up of lab facilities. We have set the facilities to handle air-sensitive chemicals, especially a glovebox specifically modified to enable sample preparation (ball milling, pressing, arc welding). We have also developed procedures for the preparation of important chemical reagents based on highly reactive silicon species. Besides, we have developed protocols enabling to use high pressures to trigger phase transformations into nanoparticles, including diamond anvil cells.

(2) In situ devices. We have designed a new device enabling to probe in situ chemical reactions in inorganic molten salts between 200 and 1000 °C, the conditions of formation of some gem stones and of the new materials we are targeting. This oven provides access to multiple techniques based on synchrotron radiation for addressing the way matter transforms in these geo-inspired conditions. We have also developed a method to understand the nature and evolution of the active species operating in nanomaterials during their use in electrocatalytic energy conversion. This approach combines state-of-the-art analytical transmission electron microscopy and in situ synchrotron radiation-based spectroscopy. We have successfully applied this method to multi-element catalysts of electrocatalytic water splitting for H2 production and unveiled unexpected redox switches during the operation of these nanomaterials.

(3) Synthesis of new nanomaterials. We have developed the methodology proposed in GENESIS to reach new nanomaterials. Among the achievements on materials synthesis, our first highlight is the design of a pathway to design multimetallic silicide nanocrystals by reacting silicon nanoparticles in molten salts. These nanomaterials exhibit high performances for electrocatalytic water oxidation, a key reaction for the production of hydrogen from water. The second highlight is the discovery of a new compound made of two different anions and built from a molten salt as a totally new crystal structure, which shows significant activity for hydrogen production from photocatalytic water splitting.

(4) Coining an interdisciplinary field of chemical synthesis. We have defined the foundations of geo-inspired materials synthesis, the concept underlying the GENESIS project, and the first results, through several publications and communications in international conferences.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Progresses achieved since the beginning of the project have gone beyond state-of-the-art in two directions.

The first direction is characterization methodologies. The development of a sample environment compatible with multiple in situ techniques to probe high temperature liquids will provide the community of nanosciences, solid-state chemistry and geosciences with a versatile instrument prone to deliver new knowledge on the chemical reactivity of solids and of nanoparticles in such media, but also on crystallization mechanisms in these geo-inspired conditions. Likewise, by combining analytical transmission electron microscopy and in situ synchrotron radiation-based spectroscopy, we could highlight how the catalytic cycles of the oxygen reduction and oxygen evolution reactions can be controlled by adjusting the cationic compositions of perovskite nanocrystals. These reactions are involved in fuel cells, metal-air batteries and water electrolysers, hence their prime importance for the energy transition.

The second direction is the design of new nanomaterials. We developed a reaction pathway to discover the first iron-doped nickel silicide nanocrystals, by converting silicon nanoparticles into molten salts. In oxidative conditions, these new nanocrystals transform into heterostructures that deliver high performances for the electrocatalysis of the water oxidation reaction. We also discovered a new compound combining two anions into a new atomic framework, enabling water photoelectrolysis for hydrogen production.

In the near future, we will capitalize on the methodological developments described above to shed light on the reaction mechanisms involved in the crystallization of nanoparticles with new chemical compositions in high temperature molten salts and under high pressures. We will use this new knowledge to control chemical reactivity and search for the first nanocrystals of compounds previously reported only in the bulk state, as well as new compounds. We will then further address the electrocatalytic properties of the achieved nanomaterials, for dihydrogen production from water and for carbon dioxide conversion into high added-value products.

Highlight 1: a multianionic compound discovered from molten salts

Highlight 2: nickel iron silicide nanocrystals as precatalysts for water oxidation