Ultrafast ammonia-driven, microwave-assisted synthesis of nitrogen-doped graphene quantum dots and their optical properties

Abstract

Abstract:For the first time, a facile, ultrafast, ammoniadriven microwave-assisted synthesis of high-quality nitrogen-doped graphene quantum dots (NGQDs) at room temperature and atmospheric pressure is presented. This one-step method is very cheap, environment friendly, and suitable for large-scale production. The as-synthesized NGQDs consisting of one to three graphene monolayers exhibit highly crystalline quality with an average size of 5.3 nm. A new fluorescence (FL) emission peak at 390 nm is observed, which might be attributed to the doped nitrogen atoms into the GQDs. An interesting red-shift is observed by comparing the FL excitation spectra to the UV-visible absorption spectra. Based on the optical properties, the detailed Jablonski diagram representing the energy level structure of NGQDs is derived.

Fluorescence studies of the interaction between chloramphenicol and nitrogen‐doped graphene quantum dots and determination of chloramphenicol in chicken feed

“…Absorption peaks at approximately 205 nm (6.05 eV), 230 nm (5.39 eV), 330 nm (3.76 eV), and 400 nm (3.10 eV) are present in the spectrum of the N‐GQDs. Absorption at 205 and 230 nm indicated π → π * C=C transitions, and absorption at 330 and 400 nm indicated n → π * C = O and C–N transitions, respectively . The fluorescence emission spectra of the GQDs and N‐GQDs at different excitation wavelengths are shown in Figure b,c, respectively.…”

“…N‐GQDs have been synthesized using glucose, glycine, or citric acid as a carbon source and ammonia, glycine, tris(hydroxymethyl) aminomethane, or 3,4‐dihydroxy‐ l ‐phenylalanine as a nitrogen source. Zheng et al reported an ultrafast, ammonia‐driven, microwave‐assisted N‐GQD synthesis with glucose and ammonia, which were placed in a commercial microwave oven at 900 W for 1 min. This one‐step, microwave‐assisted synthesis of high‐quality N‐GQDs was performed at room temperature (25 ± 1°C) and atmospheric pressure.…”

“…Therefore, we prepared N‐GQDs with a modified version of this method and investigated the feasibility of determining CAP concentrations based on luminescence quenching. The N‐GQDs used in this study were prepared via a modification of the methods reported by Zheng et al and Qu et al Citric acid and urea were used as carbon and nitrogen sources, respectively, in the microwave‐assisted synthesis. The photophysical properties of the N‐GQDs, the interaction between CAP and N‐GQDs, and the feasibility of CAP determination in chicken feed were investigated in this study.…”

Simply synthesized nitrogen-doped graphene quantum dot (NGQD)-modified electrode for the ultrasensitive photoelectrochemical detection of dopamine

“…GQDs possess stacked graphene-like sp 2 carbon-type layer structures inside the dots, endowing them with some of the unusual properties of graphene such as unique edge effects and quantum confinement, leading to broadband optical absorption [24,25]. GQDs have attracted increasing interest in many fields, such as electrochemical biosensors, photoelectrochemical biosensors, drug delivery, bioimaging, and energy conversion [26][27][28][29]. Furthermore, both theoretical and experimental results have indicated that the introduction of nitrogen atoms into the carbon lattice of quantum dots (NGQDs) would tailor the electronic property and chemical reactivity of GQDs [30][31][32][33].…”

Carbon Nanotube Modified V2O5 Porous Microspheres as Cathodes for High‐Performance Lithium‐Ion Batteries

“…One efficient strategy to overcome the drawbacks and improve the electrochemical performance of the electrode is through structure design, such as nanoparticles, nanotubes, and porous balls . These structures not only easily enlarge the contact area between electrode and electrolyte, but also reduce the path length for lithium ions .…”