Department of Chemical Engineering, National Taiwan University of Science and Technology, Daan Dist, Taipei City 10607, Taiwan; R&D Center for Membrane Technology, Chung Yuan Christian University, Chungli Dist, Taoyuan City 32023, Taiwan.
Department of Industrial Chemistry, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 May 5;272:120963. doi: 10.1016/j.saa.2022.120963. Epub 2022 Jan 29.
In this study, we prepared nitrogen-doped carbon dots (xNCDs) using hydrothermally-treated bitter tea oil residue with urea for the detection of metal ions by monitoring the photoluminescence quenching. The quantum yields of the xNCDs increased from approximately 3.85% (CDs) to 5.5% (3NCDs) and 7.2% (1NCDs), revealing that nitrogen doping effectively increases the fluorescence emission. The increased emission of the xNCDs can be attributed to radiative recombination resulting from the π-π* transition of the C=C or the n-π* transition between the C=O or N=O of sp units. Moreover, the CDs have abundant surface-attached phenolic and hydroxyl groups that coordinate with Fe ions and quench the fluorescence. Conversely, Hg ions preferentially adsorb on nitrogen-containing groups, such as amide-carbonyl groups (O=C-NH) and pyridinic and pyrrolic functionalities, on the surface of the NCDs owing to their strong affinity, quenching the substantial photoluminescence emissions. Our results suggest that bitter tea oil residue-derived carbon dots can be used to selectively detect metal ions, such as Fe and Hg, by doping with nitrogen using urea as a nitrogen precursor.
在这项研究中，我们使用水热法处理的苦茶油渣和尿素来制备氮掺杂碳点（xNCDs），通过监测光致发光猝灭来检测金属离子。xNCDs 的量子产率从约 3.85%（CDs）增加到 5.5%（3NCDs）和 7.2%（1NCDs），表明氮掺杂可以有效地增加荧光发射。xNCDs 的发射增加可以归因于π-π跃迁的 C=C 或 sp 单元的 C=O 或 N=O 之间的 n-π跃迁导致的辐射复合。此外，CDs 具有丰富的表面附着的酚基和羟基，可以与 Fe 离子配位并猝灭荧光。相反，Hg 离子由于其强亲和力而优先吸附在 NCDs 表面上的含氮基团上，例如酰胺羰基（O=C-NH）和吡啶基和吡咯基官能团，猝灭大量的光致发光发射。我们的结果表明，通过用尿素作为氮前体制备氮掺杂，可以使用苦茶油渣衍生的碳点选择性地检测金属离子，如 Fe 和 Hg。
