Transition Metal Sensing with Nitrogenated Holey Graphene: A First-Principles Investigation

The toxicity of transition metals, including copper(II), manganese(II), iron(II), zinc(II), hexavalent chromium, and cobalt(II), at elevated concentrations presents a significant threat to living organisms. Thus, the development of efficient sensors capable of detecting these metals is of utmost importance. This study explores the utilization of two-dimensional nitrogenated holey graphene (C₂N) nanosheet as a sensor for toxic transition metals. The C₂N nanosheet's periodic shape and standard pore size render it well suited for adsorbing transition metals. The interaction energies between transition metals and C₂N nanosheets were calculated in both gas and solvent phases and were found to primarily result from physisorption, except for manganese and iron which exhibited chemisorption. To assess the interactions, we employed NCI, SAPT0, and QTAIM analyses, as well as FMO and NBO analysis, to examine the electronic properties of the TM@C₂N system. Our results indicated that the adsorption of copper and chromium significantly reduced the HOMO-LUMO energy gap of C₂N and significantly increased its electrical conductivity, confirming the high sensitivity of C₂N towards copper and chromium. The sensitivity test further confirmed the superior sensitivity and selectivity of C₂N towards copper. These findings offer valuable insight into the design and development of sensors for the detection of toxic transition metals.