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Kinetics of nitrogen-doped carbon dot formation: Via hydrothermal synthesis
Ogi T.a, Aishima K.a, Permatasari F.A.a, Iskandar F.b, Tanabe E.c, Okuyama K.a
a Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima, 739-8527, Japan
b Department of Physics, Institute of Technology Bandung, Bandung, West Java, 40132, Indonesia
c Hiroshima Prefectural Institute of Industrial Science and Technology, Higashi-Hiroshima, 739-0046, Japan
[vc_row][vc_column][vc_row_inner][vc_column_inner][vc_separator css=”.vc_custom_1624529070653{padding-top: 30px !important;padding-bottom: 30px !important;}”][/vc_column_inner][/vc_row_inner][vc_row_inner layout=”boxed”][vc_column_inner width=”3/4″ css=”.vc_custom_1624695412187{border-right-width: 1px !important;border-right-color: #dddddd !important;border-right-style: solid !important;border-radius: 1px !important;}”][vc_empty_space][megatron_heading title=”Abstract” size=”size-sm” text_align=”text-left”][vc_column_text]© The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2016.Carbon dots (CDs) have attracted great attention because of their unique luminescence properties, chemical inertness, thermal stability, high water solubility, low toxicity, and ease of functionalization. Here, the kinetics of nitrogen-doped CD (N-CD) formation by hydrothermal synthesis were evaluated in an attempt to realize the rapid and efficient production of N-CDs. A series of N-CDs was synthesized using various heating rates, reaction times, reaction temperatures, and precursor concentrations. Characterization of the series of N-CDs indicated that N-CD formation is a first-order reaction with a reaction rate constant of 0.634 min-1. In addition, systematic investigation revealed that synthesis temperature is a more important factor to obtain highly fluorescent N-CDs than reaction time. Citric acid amides are formed by the reaction between citric acid and urea at 130 °C and N-CDs consisting of two or three citric acid amide molecules are formed through dehydration, deammoniation and dehydrogenation of citric acid at 150 °C. By adjusting the operating conditions, N-CDs with a highest quantum yield of 39.7% could be produced at a production rate of 50 g h-1 with a reaction time of 16 min. The N-CDs were then embedded in polyvinyl alcohol (PVA) nanofibers. The luminescence intensity of the N-CD-PVA composite nanofibers was more than twice that of the N-CDs in solution.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Author keywords” size=”size-sm” text_align=”text-left”][vc_column_text][/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Indexed keywords” size=”size-sm” text_align=”text-left”][vc_column_text][/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Funding details” size=”size-sm” text_align=”text-left”][vc_column_text]This work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers 26709061 and 25620164. We thank Drs Naoya Tochio and Junichi Kakimura from Hiroshima University for NMR analyses.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”DOI” size=”size-sm” text_align=”text-left”][vc_column_text]https://doi.org/10.1039/c6nj00009f[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/4″][vc_column_text]Widget Plumx[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][/vc_column][/vc_row]