New Modeling Shows Catalyst Frameworks Can Handle Heavy Metal Loads Without Interference
Researchers built large-scale computational models proving that covalent organic frameworks can pack high densities of catalytic metal centers without the centers interfering with each other's performance. The finding validates a promising water-oxidation mechanism and clears a major design hurdle for scaling up these catalysts in industrial green hydrogen and energy storage applications.
Originaltitel: Large-Scale Modeling Revealing the Ability of Covalent Organic Frameworks to Function High Loading of Catalytic Centers
Covalent organic frameworks (COFs) have been shown to be excellent electrocatalyst platforms, particularly when decorated with atomically dispersed transition metal centers. Large pore-size COFs enable high metal loadings but at the same time introduce challenges for mechanistic investigations using computational methods due to their large size and simultaneous interactions with electrodes and electrolytes. Herein, we designed a large-scale model with multiple metal sites of COF–Co to investigate the validity of the recently proposed intramolecular hydroxyl nucleophilic attack (IHNA) pathway for the formation of an O–O bond in water oxidation catalysis. Due to the high metal loading, it is possible that there is interference between the metal centers, and notably, such metal–metal electronic couplings can only be explicitly investigated using large-scale models that go beyond the limitations of simplified single-site approaches. Using a model with nine cobalt centers, we find no evidence of interference, and the proposed IHNA mechanism remains plausible in the large-scale model. The atomically dispersed catalytic centers were confirmed to be electronically isolated within the scaled model, operating as molecular catalysts in the material and thereby validating the applicability of the single metal-site model. Furthermore, by combining molecular dynamics simulations with an empirical valence bond (EVB) analysis, the COF–Co catalyst exhibited high environmental insensitivity, attributed to the IHNA mechanism and the stable microenvironment. This study offers valuable insights into model selection for mechanistic investigations and the design of efficient, robust, and environmentally insensitive catalysts.