Preparation of Carbon Nitride Dots with Sizes Larger than 20 nm

Abstract

Featured Application: The prepared carbon nitride dots have potential applications in fluorescent sensing, bioimaging and photocatalysis.Abstract: Carbon nitride dots (CNDs) were obtained via carbonization of polymer formed via the reaction of 1, 2-ethylenediamine (EDA) and CCl 4 . The average diameter of CNDs is calculated to be ca. 44 nm. They possess solubility in water and polar organic solvents. Appl. Sci. 2019, 9, 464 2 of 5 CharacterizationThe optical properties of the CNDs were measured by UV-visible spectrometer (U-3010, Hitachi, Tokyo, Japan) and fluorescence spectrometer (LS 55, PerkinElmer, Waltham, MA, USA), respectively. The morphology and structure of CNDs were observed by atomic force microscope (AFM, SPM-9600, Shimadzu, Tokyo, Japan), scanning electron microscope (SEM, Sirion 200s, JEOL, Tokyo, Japan), and transmission electron microscope (TEM, H-7560B, Hitachi, Tokyo, Japan) at 80 kV, respectively. Results and DiscussionAs shown in Figure 1, the synthesis of CNDs was carried out by thermal treatment of carbon nitride polymer formed via the reaction of EDA and CCl 4 . After heat treatment, the polymer underwent cross-linking and ring-formation [16]. The yellow solid at the top of the inner wall of the quartz tube was collected as our CNDs. These have solubility in water and polar organic solvents. The residual solid with a black color at the bottom of the inner wall of the quartz tube was discarded. This does not dissolve in water, however can disperse in polar organic solvents such as N, N-dimethylformamide and ethanol.Appl. Sci. 2019, 9, x 2 of 5Appl. Sci. 2019, 9, 464 4 of 5 ConclusionsCNDs with an average diameter of ca. 44 nm were synthesized via carbonization of a polymer precursor formed via the polymerization of EDA and CCl 4 . The prepared CNDs have sizes ranging from 23 to 70 nm and emit strong blue light under 360 nm excitation. In addition to their good solubility in water and polar organic solvents, these properties benefit the CNDs for further applications in bioimaging, fluorescence sensing, and optoelectronics devices. The method reported in this work for preparing CNDs is scalable and expands the size range of synthesized CNDs.

Emerging Construction Materials and Sustainable Infrastructure

“…This issue focuses on the latest development in "Emerging Construction Materials and Sustainable Infrastructure". In the study of properties of sustainable construction materials, "green" concrete materials [20][21][22][23], composite materials [24,25], recycled materials [26][27][28], soil/rock materials [29,30] and other novel environmentally friendly construction materials [31,32] are reported in this issue. The investigations of the behaviours of structures constructed with different materials include demolished concrete structures [33,34], high-performance concrete structures [35], steel structures [36,37], steel-concrete composite structures [38,39] and fiber-reinforced polymer (FRP)-concrete hybrid structures [40][41][42][43].…”