Nitrogen dots as reductant and stabilizer for the synthesis of AgNPs/N-dots nanocomposites for efficient...

A simple method was developed for the preparation of silver nanoparticles (AgNPs) by using amino-functionalized nitrogen dots (N-dots) as reductant and stabilizer under mild conditions. N-dots were hydrothermal synthesized using 2-azidoimidazole as the precursor in aqueous ammonia. The as prepared N-dots were rich in nitrogen and oxygen-containing functional groups and exhibit strong reducing capacity. Therefore, AgNPs were rapidly synthesized under mild conditions based on N-dots serving as the reducing agent, the reaction time and temperature were 5min and 40°C, respectively. Moreover, owing to the abundant functional groups on the surface of N-dots, the obtained AgNPs/N-dots nanocomposites with the average diameters of 12.9nm were well dispersed and stable at 4°C for at least two months. Furthermore, the synthesized AgNPs/N-dots showed high surface-enhanced Raman scattering (SERS) activity and provided a sensitive SERS sensing ability for malachite green (MG) and crystal violet (CV) in aquaculture water, with the low detection limit (S/N = 3) of 2.7nmol/L and 2.0nmol/L, respectively, corresponding with the wide linear range from 10.0 to 1000.0nmol/L for MG and 5.0-100.0nmol/L for CV. This method offers an easy and low-cost way to prepare AgNPs/N-dots substrates and makes SERS detection more practicable.