Hydrogen and oxygen evolution reactions on single atom catalysts stabilized by a covalent organic framework

Single Atom Catalysts (SACs) bridge homo- and heterogenous catalysis and are promising for several chemical processes of interest, including water splitting. SACs can form reaction adducts that do not likely form on conventional metal catalysts. Besides the typical supporting matrices made by carbon-based materials, Covalent Organic Frameworks (COFs) are gaining attention because of the possibility to design the hosting cavity to stably bind the active metal site. We performed a density functional theory (DFT) study of a set of SACs made by transition metal atoms embedded in a recently synthesized COF material. We explored their reactivity in Hydrogen and Oxygen Evolution Reactions (HER and OER, respectively). SACs@COF can form several intermediates with no counterpart on the classical metal electrodes, with important implications on the reaction mechanism. The results are useful for the design of novel catalytic materials and for the identification of interpretative/predictive activity descriptors.