Liquid-Assisted Grinding - from Fundaments to Applications

Project Information

GrindCore

Grant agreement ID: 894075

DOI

10.3030/894075

Project closed

EC signature date 16 March 2020

Start date 1 February 2021

End date 29 April 2024

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 243 763,20

EU contribution

€ 243 763,20

Coordinated by

RUDER BOSKOVIC INSTITUTE
Croatia

Periodic Reporting for period 2 - GrindCore (Liquid-Assisted Grinding - from Fundaments to Applications)

Reporting period: 2023-02-01 to 2024-01-31

Summary of the context and overall objectives of the project

The action and my future plans beyond are dedicated to understanding of the processes underlying the further development of new technologies based on solid-state reactions that will help energetics and industry to prevent the imminent global environmental threats. Specifically, this research is intended to improve the established scientific collaboration between EU and Canada in the field of mechanochemistry, an emerging and increasingly important field of contemporary preparational chemistry with minimized environmental impact. From the fundamental fact that any chemical reaction requires mobility of reactant molecules to allow their collisions, it seems that regularly observed amorphous or even liquid phases play an active role at the first stages of solid-state reactions, acting as a medium that enables mobility of involved chemical species, thus providing an environment in which a chemical reaction is possible. Additionally, it is clear that solid-state chemical reactions are initiated by the contact of two substances. However, this fundamental aspect has not been dealt with in sufficient detail so far. Our experimental approach enable us to qualitatively and quantitatively detect and characterize the evolution of chemical species involved in fundamental processes under the hood of solid-state reactivity. In a specific context of green chemistry, understanding and optimization of the mechanochemical procedures, which are inherently solvent-free or use minimal, catalytic amounts of solvents, is highly beneficiary to optimization of the performance of chemical industry with minimization of its environmental impact. In perspective, this action could position both included institutions at the fore-front of clean technologies and sustainability on the global scale.

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

The very start of the project was focused on detailed planning of the experimental work to be done. The concrete chemical problems and systems were then addressed and investigated during the action.
The extensive use of various spectroscopic and thermal methods, together with powder X-ray diffraction, as a method for structure elucidation, enable a detailed and deep insight into the background of mechanochemical and other solid-state reactions. Specifically, the project was focused to: liquid-assisted grinding (LAG) preparations, and diffusion-driven solid-state interface reactions. Extensive use of synchrotron radiation enabled a detailed in-situ monitoring.
A concrete experimental work was also started during the first period of implementation of the project. Specifically, the mechanochemical exfoliations of layered molybdenum disulfide-type materials were performed by addition of ammonia borane, which is expected to intercalate the layers. Additional benefit of mechanochemical approach is an extensive introduction of defects to starting material, thus maximizing the number of exposed reactive sites, providing a route toward the innovative systems, potentially applicable for photocatalytic conversion of solar radiation to useful energy.
As an extension of the previously published work on diffusion-driven solid-state reactions, that include formation of the intermediate eutectic liquid intermediate phase, preliminary experiments toward the mechanochemical route to novel polydentate polymeric ligands, were performed. These systems are also potentially applicable for energy conversion systems.
Having a large amount of high-quality data on solid-state reactivity, acquired during the 1st reporting period, the reintegration phase was focused to analysis and publication of these results. This resulted in several publications, and some of them are under review or under preparation in the moment of writing this report. The results of this project were a basis for proposal of the research project to the Croatian Science Foundation, which is entirely a continuation of this action.
Results of this project were presented on conferences and in scientific publications. PI was a member of the Local Organizing Committee of the 3rd and 4th Solid State Science and Research conference.
Various forms of science communication were also performed during the project, which are extended by the PI's activities as an ambassador of the EU Climate Pact. The PI prepared the appendices for high school textbooks in Chemistry.

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)

To understand the mechanochemical reactivity, one should understand various processes underlying it. First, solid-state interface reactions should be considered, which are conceptually a frozen mechanochemical event. Here we addressed a process which is extremely fast in mechanochemical conditions. Using the brilliance of synchrotron radiation, we obtained a highly detailed insight into these processes, which in a unique way shed a light to overall solid-state reactivity. These results also provide a milestone for further development of innovative real-world applicable systems for energy conversion and storage.
The question on the role of liquids in LAG reactions was addressed to inorganic reactionsso far poorly investigated. As a model system, preparations of Li-lanthanide borohydrides and reactions of Cu(II) halogenides with alkali halogenides giving Ruddlesden-Popper perovskites were chosen. The extensive use of synchrotron PXRD monitoring gave a clear picture of this reactivity, through reaction profiles.
Since resonant acoustic mixing (RAM) was recently introduced as a novel and highly perspective mechanochemical method, it was highly interesting to compare ball milling with RAM. It was observed that, for inorganic reactions, ball milling remains significantly more efficient.
On the other hand, it is important to understand the action of balls. They strike, grind and shear the chemical system. For this purpose, a good systems are layered materials, highly applicable for energy comnversion. Thus, the experiments are performed on the semiconductive layered systems, which gave rise to highly promising materials for photocatalytic water splitting.
The third step is investigation of the action of the intermediate liquid phase, in-situ developed or introduced by addition of the catalytic amount of liquid. Understanding of these processes is the main focus of this project, and at this stage the experiments are under preparation.
Having a large amount of high-quality data on solid-state reactivity, acquired during the 1st reporting period, the reintegration phase was focused to analysis and publication of these results. The comparative analysis of mechanochemical with solid-state interface reactions provided a deep and unique insight into the fundamental details of mass transport in solid-state systems, enabled by formation of amorphous or, in the extreme cases, liquid intermediate phase, which enable efficient flux, mixing and collisions of involved species, making this process a driving force of solid-state reactivity. During this project, however, we were able to investigate only a limited set of such reactions. Thus, the continuation of the investigations of these systems, which are planned in the framework of the proposed project, based on the results of this action, will justify the generality in solid-state reactivity. This, we expect, will establish a firm ground for further development of sustainable chemical procedures based on mechanochemistry.

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