High-throughput synthesis and characterisation of metal-organic framework thin films for volatile compound sensing

Project Information

LibMOF

Grant agreement ID: 101110882

DOI

10.3030/101110882

Project closed

EC signature date 9 March 2023

Start date 1 April 2023

End date 31 March 2025

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 155 559,36

Coordinated by

INSTITUT JOZEF STEFAN
Slovenia

Periodic Reporting for period 1 - LibMOF (High-throughput synthesis and characterisation of metal-organic framework thin films for volatile compound sensing)

Reporting period: 2023-04-01 to 2025-03-31

Summary of the context and overall objectives of the project

Metal-Organic Frameworks (MOFs) offer the possibility to tailor their nano-pore environment and capture only specific molecules, making them an ideal candidate as a receptor in gas sensors. In order to mimic human olfaction, several receptors with different selectivity toward volatile organic compounds (VOCs) are combined in an array of sensors to form an electronic nose (e-nose). High-quality thin films of MOFs are required for their integration in these sensor arrays; however, their synthesis has proven challenging due to a large number of parameters that influence the film quality. The main goal of the LibMOF project was to establish a high-throughput (HT) synthesis method to screen the synthesis conditions for MOF thin films more efficiently. The proposed HT approach is about 25 times faster than conventional synthesis and produces about 100 times less chemical waste. The project is structured around three key objectives:
- Develop a micro-reactor approach for screening the synthesis conditions of MOF thin films.
- Characterisation of thin film arrays with a focus on properties relevant to gas sensing.
- Evaluating the sensing properties of MOF thin films for use in electronic noses.
Through achieving these objectives, the LibMOF project addresses several open challenges in the field of nanoporous materials and significantly contributes to the understanding of synthesis conditions for high-quality MOF thin films and their integration in gas sensors. The project’s findings bridge research areas that are typically treated separately: synthetic chemistry, material science, nanoporous materials and microelectronics; hence, the project fosters interdisciplinary collaborations.

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 LibMOF project delivered on its overarching objective of developing high-throughput (HT) methodologies for synthesizing and characterizing metal-organic framework (MOF) thin films. To reach that overarching objective, a novel approach was developed using a mould with an array of 25 microreactor wells that enabled parallel solvothermal growth of MOF films under varied synthesis conditions. The developed HT platform allowed for systematic screening of parameters such as metal and linker concentrations, substrate surface, and temperature, using minimal reagent volumes (~0.1 mL per well). This methodology allowed 25 unique reaction conditions to be tested simultaneously on a single substrate, enabling the rapid optimisation of synthesis conditions to obtain suitable thin film morphology, homogeneity, and crystallinity. The resulting film deposits, each produced at unique conditions, were characterised using optical microscopy, SEM, and AFM.
The unprecedented effectiveness of the HT approach enabled the targeted characterization of MOF thin films with suitable properties. Films were studied using atmosphere-controlled dielectric spectroscopy, which provided relevant information for gas sensing based on capacitive signal readout. Simultaneously, spectroscopic ellipsometry has been used to study the optical properties of deposited structures. Spectroscopic ellipsometry measurements yielded quantitative data about the gas adsorption in MOF films and provided complementary information necessary to accurately interpret dielectric spectroscopy data.
The developed HT methodology enabled rapid, cost-effective, and environmentally friendly screening of synthesis conditions for the deposition of MOF thin films, which represents a major leap toward a more efficient research approach. These achievements mark a significant leap toward future AI-guided materials optimisation, which would significantly speed up the pace of discovery beyond what is achievable with traditional methods.
The results have been published in two peer-reviewed articles in high-impact open-access journals (Journal of Materials Chemistry A, ACS Applied Electronic Materials), as well as in one open-access preprint, which is at the time under review in a high-impact journal.

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)

The LibMOF project has delivered several innovations and findings that advance the current state of the art in the synthesis and application of MOF materials for chemical sensing. While previous research investigated the influence of synthesis conditions on MOF film growth by a single experiment at the time, the LibMOF project is the first to successfully implement a high-throughput (HT) methodology for MOF thin film synthesis, enabling rapid, parallel screening of synthesis parameters with minimal reagent use. The development of a 25-well microreactor array for solvothermal film growth allowed systematic variation of synthesis conditions (e.g. precursor concentration, time, temperature) on a single substrate. This method is approximately 25 times faster and 100 times less wasteful than conventional approaches, representing a transformational improvement in both efficiency and sustainability. The findings attained during the LibMOF project will accelerate the discovery and integration of MOF materials for sensing applications and present a significant step toward practical, miniaturised MOF-based sensors.

High-thoughput approach for MOF thin film deposition.