Ordered assemblies of silver nanoparticles on carbon nitride sheets and their application in the non-enzymatic...

The fabrication of ordered assemblies of noble metal nanoparticles on two-dimensional sheets is very challenging. We report here a facile bottom-up self-assembly method for the formation of ordered assemblies of silver nanoparticles on carbon nitride sheets. The ultrasonication of aqueous graphitic carbon nitride quantum dots (g-CNQDs) in the presence of Ag⁺ ions produces a silver-carbon nitride (Ag-CN_x) composite. Ordered assemblies of monodispersed silver nanoparticles on thin carbon nitride sheets are produced by the evaporation of an aqueous solution of these silver-carbon nitride composites. On evaporation of this solution, two-dimensional sheets are formed as a result of the condensation of g-CNQDs on the solid substrate. On drying, the silver nanoparticles are located in the voids of the carbon nitride. A glassy carbon electrode modified with these silver nanoparticle-carbon nitride sheets can be used as a highly sensitive electrochemical non-enzymatic sensor for H₂O₂ and glucose. The lowest detection limits for H₂O₂ and glucose were 0.6 nM and 0.6 μM, respectively. In addition, the ON-OFF-ON fluorescence response of these g-CNQDs was used for the highly sensitive detection of Ag⁺ ions and cysteine in aqueous media. The detection limits for Ag⁺ ions and cysteine were 50 and 80 nM, respectively.