Abstract
Advanced deposition routes are vital for the growth of functional metal-organic thin films. The gas-phase atomic/molecular layer deposition (ALD/MLD) technique provides solvent-free and uniform nanoscale thin films with unprecedented thickness control and allows straightforward device integration. Most excitingly, the ALD/MLD technique can enable the in situ growth of novel crystalline metal-organic materials. An exquisite example is iron-terephthalate (Fe-BDC), which is one of the most appealing metal-organic framework (MOF) type materials and thus widely studied in bulk form owing to its attractive potential in photocatalysis, biomedicine, and beyond. Resolving the chemistry and structural features of new thin film materials requires an extended selection of characterization and modeling techniques. Here we demonstrate how the unique features of the ALD/MLD grown in situ crystalline Fe-BDC thin films, different from the bulk Fe-BDC MOFs, can be resolved through techniques such as synchrotron grazing-incidence X-ray diffraction (GIXRD), Mössbauer spectroscopy, and resonant inelastic X-ray scattering (RIXS) and crystal structure predictions. The investigations of the Fe-BDC thin films, containing both trivalent and divalent iron, converge toward a novel crystalline Fe(III)-BDC monoclinic phase with space group C2/c and an amorphous Fe(II)-BDC phase. Finally, we demonstrate the excellent thermal stability of our Fe-BDC thin films.
| Original language | English |
|---|---|
| Pages (from-to) | 6489-6503 |
| Journal | Chemistry of Materials |
| Volume | 36 |
| Issue number | 13 |
| DOIs | |
| Publication status | Published - 9 Jul 2024 |
| MoE publication type | A1 Journal article-refereed |
Funding
Funding was received from the European Union (ERC AdG, UniEnMLD, No. 101097815). Views and opinions expressed are however those of the authors only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. This work was also partly supported by the Finnish Cultural Foundation (THERMOF), Magnus Ehrnrooth Foundation, KU Leuven (GSFAH/22/001), Research Foundation Flanders (1263622N), JSPS KAKENHI (JP22H05143; Transformative Research Areas (A) \u201CSupra-ceramics\u201D), and Scandinavia-Japan Sasakawa Foundation. We acknowledge the European Synchrotron Radiation Facility (ESRF) for provision of synchrotron radiation facilities (beamline ID26) under the proposal number CH-6525 (DOI: 10.15151/ESRF-ES-894388406). We also acknowledge Diamond Light Source for time on Beamline I07 under proposal si29967 and thank Francesco Carla\u0300, Jonathan Rawle, Jorid Smets, and Jesu\u0301s Ga\u0301ndara-Loe. We also thank CSC \u2013 the Finnish IT Center for Science for computational resources. Anni Virta and Mikhail Kuklin are acknowledged for contributions to the USPEX crystal structure predictions. Olga Partanen is acknowledged for contributions to the thermal stability studies. Miwa Saito and Yusuke Asai are acknowledged for contributions to the in situ FTIR experiments.