(530d) First-Principles Insight into Synthesis and Electrocatalytic Activity of Porphyrin-Based Covalent Organic Frameworks

Here, we employ density functional theory (DFT) calculations to understand structural and electrocatalytic properties of porphyrin-based covalent organic frameworks (POR-COFs). Recently, we have proposed a new electrochemical process for in situ bottom-up synthesis of POR-COFs, and have investigated their electrocatalytic activity for oxygen reduction reaction (ORR).[*] Our synthesized POR-COFs have the ability to be incorporated with an intercalated sub-lattice of small organic molecules (e.g., pyridine). We have shown that such a sub-lattice can be used to tune the electrocatalytic properties of the stacked POR-COF system. Here, we investigate the strategies to further improve the ORR electrocatalytic activity of these POR-COFs by introducing single-atom metallic dopants into the porphyrin rings. We study the ORR mechanism in basic media for these single-atom catalyst (SAC) systems, and reveal fundamental opportunities provided to go beyond some of the limitations on electrocatalytic ORR activity encountered on more conventional extended systems, dictated by traditional scaling relationships. In addition to a survey on different metallic dopants, the role of the solvent, dimensionality, different stacking patterns and the COF morphology on tuning and optimizing ORR activity will be discussed. Our previously mentioned novel electrochemical synthesis method allows for intercalating a sub-lattice of organic molecules into the COF structure, this can also be used as a control knob to change the electronic structure and morphology of the COF system and consequently its electrocatalytic properties.

[*] Tavakoli, E., Kakekhani, A., Kaviani, S., Tan, P., Mohammadi Ghaleni, M., Asle Zaeem, M., Rappe, A.M. and Nejati, S., 2019. In Situ Bottom-up Synthesis of Porphyrin-based Covalent Organic Frameworks. Journal of the American Chemical Society 2019, 141, 50, 19560-19564