A new sulfur-doped source and synergistic effect with nitrogen for carbon dots produced from glucose<xref rid="cpb_28_12_128102fn1" ref-type="fn">*</xref><fn id="cpb_28_12_128102fn1"><label>*</label><p>Project by the National Natural Science Foundation of China (Grant Nos. 51571085, 11805052, and 61705062), the Research Project for Basic and Forefront Technology of Henan Province, China (Grant No. 162300410219), and the Doctor Foundation of Henan Polytechnic University, China (Grant No. B2014049).</p></fn>

A new sulfur-doped source and synergistic effect with nitrogen for carbon dots produced from glucose**

Project by the National Natural Science Foundation of China (Grant Nos. 51571085, 11805052, and 61705062), the Research Project for Basic and Forefront Technology of Henan Province, China (Grant No. 162300410219), and the Doctor Foundation of Henan Polytechnic University, China (Grant No. B2014049).

Fu Lige¹, Yin Yuehong^{1, †}, Cao Guohua^{1, ‡}, Wu Pingping¹, Wang Jian¹, Yan Lingling¹, Zhang Baoqing², Li Ming¹

(a) Fluorescence quenching and (b) comparison of fluorescence intensities of CDs after the addition of different metal ions. (c) Fluorescence quenching in the presence of Fe³⁺ ions (from top to bottom: 0, 20, 60, 100, 160, 220, 300, 400, 500, and 600 μM) and (d) relationship between the PL intensity and C-dots size and the concentration of Fe³⁺ ions.