Single-Atom Cobalt-Doped 2D Graphene: Electronic Design for Multifunctional Applications in Environmental Remediation and Energy Storage

Through atomic-scale characterization of a single cobalt atom anchored in a pyridinic N3 vacancy of graphene (Co-N3-gra), this study computationally explores three interconnected functionalities mediated by cobalt’s electronic configuration. Quantum-confined molecular prototypes extend prior bulk models, achieving a competitive catalytic activity for CO oxidation via Langmuir–Hinshelwood pathways with a 0.85 eV barrier. These molecular prototypes’ discrete energy states facilitate single-electron transistor operation, enabling sensitive detection of NO, NO2, SO2, and CO2 through adsorption-induced conductance modulation. When applied to lithium–sulfur batteries using periodic Co-N3-gra, cobalt sites enhance polysulfide conversion kinetics and suppress the shuttle effect, with the Li2S2→Li2S step identified as the rate-limiting process. Density functional simulations provide atomic-scale physicochemical characterization of Co-N3-gra, revealing how defect engineering in 2D materials modulates electronic structures for multifunctional applications.