Nitrogen-sulfur co-doped pH-insensitive fluorescent carbon dots for high sensitive and selective hypochlorite detection

Liyang Shi; Guohua Zhou; Xia Xiang; Zhen Zhang; Yongmei Jia; Peilian Liu; Zhiguo Li

doi:10.1016/j.saa.2020.118721

Nitrogen-sulfur co-doped pH-insensitive fluorescent carbon dots for high sensitive and selective hypochlorite detection

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Dec 5:242:118721. doi: 10.1016/j.saa.2020.118721. Epub 2020 Jul 20.

Authors

Liyang Shi¹, Guohua Zhou², Xia Xiang³, Zhen Zhang³, Yongmei Jia⁴, Peilian Liu⁵, Zhiguo Li⁶

Affiliations

¹ Zhejiang Provincial Collaborative Innovation Center for Bamboo Resources and High-Efficiency Utilization, Zhejiang Provincial Key Laboratory of Chemical Utilization of Forestry Biomass, Zhejiang A&F University, Hangzhou, Zhejiang 311300, China.
² School of Chemistry and Chemical Engineering, Key Laboratory of Clean Energy Materials Chemistry of Guangdong Higher Education Institutes, Lingnan Normal University, Zhanjiang, Guangdong 524048, China. Electronic address: gh-zhou@foxmail.com.
³ Department of Product Processing and Nutriology, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Hubei Key Laboratory of Lipid Chemistry and Nutrition, Ministry of Agriculture Key Laboratory of Oil Crops Biology, Wuhan 430062, China.
⁴ School of Chemistry and Chemical Engineering, Key Laboratory of Clean Energy Materials Chemistry of Guangdong Higher Education Institutes, Lingnan Normal University, Zhanjiang, Guangdong 524048, China. Electronic address: jiayongmei214@126.com.
⁵ School of Chemistry and Chemical Engineering, Key Laboratory of Clean Energy Materials Chemistry of Guangdong Higher Education Institutes, Lingnan Normal University, Zhanjiang, Guangdong 524048, China. Electronic address: liupeilian2010@126.com.
⁶ School of Chemistry and Chemical Engineering, Key Laboratory of Clean Energy Materials Chemistry of Guangdong Higher Education Institutes, Lingnan Normal University, Zhanjiang, Guangdong 524048, China.

PMID: 32717526
DOI: 10.1016/j.saa.2020.118721

Abstract

Carbon dots (CDs) are novel fluorescent carbon nanomaterial with exceptional properties and have drawn great attention in recent years. However, the preparation and applications of high-quality carbon dots remain challenging. Here, we describe a simple hydrothermal synthesis route using citric acid as a carbon source for stable fluorescent CDs. The CDs are modified with glutathione and exhibit high fluorescent quantum yields (30.2%) and excellent photo-stability. In addition, the fluorescence intensity of CDs remains stable over a wide range of pH values (3-12). Hypochlorite (ClO^-) can effectively quench the fluorescence of the CDs by destroying the pyrrolic ring and conjugate structure of the CDs. Thus, the CDs can be used to detect ClO^-. Under optimized conditions, the fluorescence intensity changes of CDs correspond selectively to ClO^- in the range of 100-800 nmol/L with a LOD of 16 nmol/L. Practical applications of the proposed method for free chlorine detection in tap water show similar results and recovery compared to the standard DPD-based method. These results suggest that the pH-insensitive CDs prepared via this facile procedure are a promising chemosensor for free chlorine and have great potential in analytical applications.

Keywords: Carbon dots; Fluorescent detection; Free chlorine; Hypochlorite; pH.