3D COFs FOR PHOTOCATALYTIC N₂ FIXATION: A COMPUTATIONAL STUDY

As a result of permanent porosity, tunability, and structural stability, covalent-organic frameworks (COFs) have been introduced in various environmental-related applications. COFs have been studied for various gas separation-related applications, primarily CO2 capture from natural gas and flue gas. The performance of COFs towards gas separation can be investigated by computational techniques, including density functional theory (DFT) and molecular simulations based on force fields. In this work, several atomistic and molecular simulations techniques are used to identify COFs for the nitrogen conversion to ammonia photocatalytically. The experimental database is screened for desired conduction, valence band, and bandgap. A total of six structures are selected from the 3D structures. COF-300 has been shown to have desirable electronic properties (bandgap approximately 3.5 eV) and the highest N₂ adsorption among the six COFs.The simulations are performed using GCMC simulations to determine the nitrogen capacity of the COFs. Structures with one of the desired valence or conduction bands with desirable bandgaps are coupled in a COF/COF junction that potentially enhances charge separation and reduces charge carrier recombination rates. The study reports a 40 COF/COF heterojunction for the required application. Such high throughput screening typically involves databases (experimental based) and results in an essential structure-function relationship that accelerates materials discovery in several energy applications.