Silver-graphene quantum dots based electrochemical sensor for trinitrotoluene and p-nitrophenol

Abstract

Abstract Silver cluster decorated graphene quantum dots act as efficient electrochemical sensors for the detection of nitroaromatic compounds due to their unique electronic properties. Herein, we report the first detailed theoretical study about the sensing ability of silver-graphene composites for the electrochemical detection of trinitrotoluene (TNT) & p-nitrophenol (p-NP). The complexes of TNT and p-NP with silver-graphene composite are quite stable as evident from their higher interaction energies (−15.64 to −70.07 kcal mol−1). The NBO charge analysis, DOS analysis, frontier molecular orbital analysis, UV–visible analysis, non-covalent interactions (NCI) & charge decomposition analysis (CDA) supported the interaction mechanism in TNT@Ag6-coronene & p-NP@Ag6-coronene complexes. NBO charge analysis results reveal that the charge is transferred from substrates to analytes except in p-NP@coronene and p-NP@coronene-Ag6 complexes. The generation of new energy states in DOS spectra reflect the chemical sensitivity of the system. Frontier molecular orbital analysis results validate a substantial decrease in the H-Lgap of silver-coronene composite on interaction with analytes. The shifting (red & blue) of λmax during interactions of analytes with silver-coronene is affirmed from excited state analysis. The NCI plots show that some steric repulsion is also there along with strong non-covalent electrostatic (M…O) & unusual van der Waals (M…H) interactions. The evaluated results of CDA validate the charge transfer interactions between various fragment pairs of complexes. The precedent results distinctly show the better sensing performance of silver-graphene composites towards TNT & p-NP.