Ren Jian, Achilleos Demetra S, Golnak Ronny, Yuzawa Hayato, Xiao Jie, Nagasaka Masanari, Reisner Erwin, Petit Tristan
Institute for Nanospectroscopy , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) , Albert-Einstein-Straße 15 , 12489 Berlin , Germany.
Department of Physics , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany.
J Phys Chem Lett. 2019 Jul 18;10(14):3843-3848. doi: 10.1021/acs.jpclett.9b01800. Epub 2019 Jun 27.
Carbon dots (CDs) exhibit outstanding physicochemical properties that render them excellent materials for various applications, often occurring in an aqueous environment, such as light harvesting and fluorescence bioimaging. Here we characterize the electronic structures of CDs and water molecules in aqueous dispersions using in situ X-ray absorption spectroscopy. Three types of CDs with different core structures (amorphous vs graphitic) and compositions (undoped vs nitrogen-doped) were investigated. Depending on the CD core structure, different ionic currents generated upon X-ray irradiation of the CD dispersions at the carbon K-edge were detected, which are interpreted in terms of different charge transfer to the surrounding solvent molecules. The hydrogen bonding networks of water molecules upon interaction with the different CDs were also probed at the oxygen K-edge. Both core graphitization and nitrogen doping were found to endow the CDs with enhanced electron transfer and hydrogen bonding capabilities with the surrounding water molecules.
碳点（CDs）具有出色的物理化学性质，使其成为各种应用的优良材料，这些应用通常发生在水性环境中，如光捕获和荧光生物成像。在这里，我们使用原位X射线吸收光谱法表征了水性分散体中碳点和水分子的电子结构。研究了三种具有不同核心结构（非晶态与石墨态）和组成（未掺杂与氮掺杂）的碳点。根据碳点的核心结构，在碳K边对碳点分散体进行X射线辐照时会检测到不同的离子电流，这可以通过向周围溶剂分子的不同电荷转移来解释。在氧K边也探测了水分子与不同碳点相互作用时的氢键网络。发现核心石墨化和氮掺杂都赋予碳点增强的电子转移能力以及与周围水分子形成氢键的能力。
