Computational Investigation of Ordered Framework Materials for Photocatalysis

Metal (MOFs) and covalent (COFs) organic frameworks comprise a class of countless porous crystalline materials with building block construction[1]. In particular, the interest in investigating this class of materials for photocatalytic applications lies in the tunability of their optoelectronic properties with different building blocks, which ideally could be assessed computationally in an efficient way to redirect experimental efforts. However, the computational exploration of MOFs and COFs for photocatalysis can be challenging due to their large unit cells that can have hundreds of atoms. Therefore, investigating the optoelectronic properties of those materials with first principles requires cost-effective alternatives. To tackle this challenge, we have adopted strategies at different levels of theory to first explore large datasets, and then focus on investigating a few materials in depth. The first approach leverages cost-effective alternatives to compute DFT-based photocatalytic descriptors at a low level of theory to assess the fundamental steps of photocatalysis, that is, light absorption, thermodynamic feasibility of the photoredox reactions, charge carrier mobility and charge separation[2]. Such an approach allowed us to shortlist promising materials, and gain insights into structure-property relationship such as the use of β-ketoenamine linkages in COFs for right band edge alignment to the hydrogen evolution reaction and enhanced charge-carrier mobility[2]. Going further, ongoing work aims to investigate the electronic band gap and related properties of our best candidates with a higher level of theory. For that purpose, we make use of non-empirical screened range separated hybrids (SRSH) in density functional theory as it enables electronic band gap calculations in close agreement with more expensive state of the art GW methods[3]. The so far promising results of using wannier localization-based optimally tuned SRSH for MOFs suggest a potential cost-effective pathway to more accurately evaluate complex physical phenomena encompassing the electronic band gap.<br/><br/>References<br/>[1] O. M. Yaghi, M. O'Keeffe, N. W. Ockwig, H. K. Chae, M. Eddaoudi, and J. Kim, “Reticular synthesis and the design of new materials,” Nature, vol. 423, pp. 705–714, June 2003.<br/>[2] B. Mourino, K. M. Jablonka, A. Ortega-Guerrero, and B. Smit, “In search of covalent organic framework photocatalysts: A dft-based screening approach,” Advanced Functional Materials, p. 2301594, 2023.<br/>[3] D. Wing, G. Ohad, J. B. Haber, M. R. Filip, S. E. Gant, J. B. Neaton, and L. Kronik, “Band gaps of crystalline solids from wannier-localization–based optimal tuning of a screened range-separated hybrid functional,” Proceedings of the National Academy of Sciences, vol. 118, Aug. 2021.