DFT study on the sensitivity of silver-graphene quantum dots for vital and harmful analytes

DFT study is performed to evaluate the sensitivity and selectivity of silver, coronene, and silver-coronene composites for the detection of gaseous analytes including ethanol, ammonia, hydrogen sulfide, and oxygen molecules. Results of interaction energies reveal that O2@Ag6-coronene (−61.06 kcal mol−1) is the most stable while NH3@coronene is the least stable (−4.00 kcal mol−1) complex. The order of Eint and % reduction in H-Lgaps are the same for analyte@Ag6 complexes i.e. O2@Ag6 > NH3@Ag6 > C2H5OH@Ag6 > H2S@Ag6. Oxygen molecule strongly interacts with silver cluster due to strong Ag⋯O electrostatic interactions. Charge transfer interactions are explored through natural bond orbital (NBO) and charge decomposition (CDA) analyses. The frontier molecular orbital (FMO) analysis reveals a significant reduction in H-Lgap in the complexes of analytes with silver-coronene composites. UV–Visible results show that the absorption maximum is shifted towards a longer wavelength (bathochromic or red shift) in most of the complexes. Non-covalent interaction (NCI) study reveals that, besides strong electrostatic interactions, weak van der Waals dispersion interactions are present in silver-coronene complexes of analytes. The generation of new energy states in occupied and virtual orbitals closer to the Fermi level in the density of state (DOS) spectra affirm the sensitivity of silver-coronene composites towards analytes. The current findings suggest that silver-coronene composites are highly selective for the sensing of oxygen molecule. The outcome of the recent study will help to design the silver-graphene sensors for selective and accurate detection of analytes.