Triple-emission nitrogen and boron co-doped carbon quantum dots from lignin: Highly fluorescent sensing platform for detection of hexavalent chromium ions

Considering that hexavalent chromium ions (Cr6+) with high toxicity poses a huge threat to human health and the ecological environment, constructing a rapid and accurate sensing platform is of great significance in detecting the toxic substance. The novel nitrogen and boron co-doped carbon quantum dots (N, B-CQDs) from lignin are synthesized as fluorescent sensors for the detection of Cr6+. The synthetic processes involve the acid hydrolysis step followed by the hydrothermal treatment step. Lignin is firstly depolymerized by cleaving ether bonds in the acidolysis, and N, B-CQDs are consequently formed by the aromatic re-fusion of lignin nanoparticles in the hydrothermal process. The lignin-derived N, BCQDs show triple emission of purple, blue and green fluorescence under the excitation of 300, 330, and 490 nm, respectively. The triple-emission N, B-CQDs are applied for the triple-channel detection of Cr6+, which exhibit highly sensitive and selective fluorescence quenching for Cr6+ with good linearity (R2 < 0.996) and very low limit of detection as 0.054, 0.049, and 0.077 lM under the excitation of 300, 330 and 490 nm, respectively. The utilization of renewable lignin as CQDs-based fluorescent sensors opens a new avenue for the rapid and accurate detection of Cr6+ through a multichannel sensing platform. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

Considering the high toxicity of hexavalent chromium ions (Cr6+) and its threat to human health and the environment, it is of great significance to develop a rapid and accurate sensing platform for detecting this toxic substance. In this study, nitrogen and boron co-doped carbon quantum dots (N, B-CQDs) derived from lignin were synthesized and used as fluorescent sensors for the detection of Cr6+. The N, B-CQDs showed triple emission and were applied for triple-channel detection, exhibiting highly sensitive and selective fluorescence quenching for Cr6+. The utilization of renewable lignin as a basis for CQDs-based fluorescent sensors opens up a new approach for the rapid and accurate detection of Cr6+ through a multi-channel sensing platform.