Red-emissive carbon dots from spinach: Characterization and application in visual detection of time

• Published in: Journal of luminescence Vol. 227; p. 117534
• Main Authors: Xu, Xiaokai, Cai, Lifeng, Hu, Guangqi, Mo, Luoqi, Zheng, Yihao, Hu, Chaofan, Lei, Bingfu, Zhang, Xuejie, Liu, Yingliang, Zhuang, Jianle
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2020
• Subjects: Carbon dots; Color change; PEI; Red emission; Time detection; Color change; Red emission; Carbon dots; PEI; Time detection
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2020.117534

As a new type of carbon nanomaterial, carbon dots (CDs) have attracted more and more attention due to their excellent properties. Here, we developed a simple, green and environmentally friendly method for preparing red-emissive CDs from spinach. The emission color of the CDs under UV light changed from red luminescence to green luminescence after one to four weeks. This was due to the change of the aggregated molecules on the surface of CDs. It was demonstrated that the nitrogen content of the CDs gradually decreased with the increase of time, since CDs combined with oxygen to form aggregates to eliminate excess nitrogen. It was further found that CDs showed the increase intensity of the emission in 500 nm wavelength and decrease intensity of the emission in 665 nm wavelength, which could be attributed to their respective emission from different molecular structures. Compared with the CDs stored for one week, the agglomeration of the CDs particles after four weeks was obvious, indicating that its light stability depended on the agglomeration structure of CDs. Due to their special properties, the CDs could be used for visual detection of time. [Display omitted] •A method for preparing red-emissive carbon dots from spinach leaves is developed.•The emission color of carbon dots changes from red to green light during four weeks.•Dropping carbon dots on the filter paper can realize visual time detection.