Facile preparation of a dual-emission paper-based fluorescent sensor based on carbon quantum dots and rhodamine B for dual-mode detection of Hg²⁺

Abstract

In this study, carbon quantum dots (CQDs) and rhodamine B (RhB) were physically mixed to construct a highly selective and sensitive ratiometric fluorescent sensor (CQDs@RhB) for the quantitative and visual detection of Hg²⁺. After adding Hg²⁺, the emission peak of CQDs at 445 nm was quenched and the peak of RhB at 575 nm remained unchanged; the ratio of the two emission peaks had a linear relationship with the Hg²⁺ concentration. The CQDs@RhB had a detection range of 0–15 µM and the limit of detection (LOD) is 65.93 nM and a color change from blue to pink was visible to the naked eye under ultraviolet light. The study revealed a static quenching mechanism of CQDs@RhB. The established method was successfully applied to the detection of Hg²⁺ in real water and rice samples with satisfactory results. In addition, a portable fluorescent paper-based sensor platform was developed using computer software assistance. The relationship with Hg²⁺ concentration was constructed by converting the pictures obtained under ultraviolet light to RGB color mode for visualization and quantitative detection of Hg²⁺. This study provides a valuable strategy for constructing a rapid detection system for Hg²⁺ in the field.

Keywords:

• Carbon quantum dots (CQDs)
• ratiometric fluorescent sensor
• Hg²⁺ detection
• visual detection

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was financially supported by the Natural Science Foundation of Qinghai (No. 2020-ZJ-702) and the National Natural Science Foundation of China (No. 21766028).

Notes on contributors

Yongzheng Yin

Yongzheng Yin received his B.S. degree in Environmental Engineering from Qinghai University in Xining, China, in 2021. He is currently pursuing his M.S. degree in chemical technology at Qinghai University, Xining, China. His research interests are in fluorescent sensors. E-mail: [email protected]

Huanhuan Lu

Huanhuan Lu received her B.S. degree in applied chemistry from Yancheng Normal College, Yancheng, China, in 2022. She is currently pursuing her M.S. degree at the College of Chemical Technology, Qinghai University, Xining, China. Her research interests are in fluorescent nanomaterials. E-mail: [email protected].

Weijun Song

Weijun Song received his B.S. degree from Sichuan Normal University, Chengdu, China, in 2001; the M.S. degree from Nanchang University, Nanchang, China, in 2006; and the Ph.D. degree in chemistry from East China University of Science and Technology, Shanghai, China, in 2019. Her research interest is comprehensive utilization of Salt Lake resources. E-mail: [email protected]

Xiaofeng Hu

Xiaofeng Hu received his B.S. degree from Wuhan University of Technology, Wuhan, China, in 2003; M.S. degree from Nanchang University, Nanchang, China, in 2008; and Ph.D. degree in chemistry from East China University of Science and Technology, Shanghai, China, in 2019. His research interest is atmospheric environmental Science research. E-mail: [email protected]

Chunyan Sun

Chunyan Sun received her B.S. degree in chemical education from Northeast Normal University, Changchun, China, in 2003; the M.S. degree in inorganic chemistry from Northeast Normal University, Changchun, China, in 2006; and the Ph.D. degree in physical chemistry from Northeast Normal University, Changchun, China, in 2009. Her research interests include materials chemistry, analytical chemistry, and salt-lake chemistry. E-mail: [email protected].