Template-free microwave-assisted fabrication of carbon dots/Zn(OH)2 composites for separation and enhancing chemical sensing

•CDs/Zn(OH)2 composites were firstly prepared by a template-free microwave-assisted route.•A self-assembly growth mechanism was proposed to explain the formation of CDs/Zn(OH)2 composites.•Zn(OH)2 nanosheets could effectively accumulate metal ions and synergistically quench the fluorescence of CDs.•The proposed sensor could enrich/separate and sensitively detect Hg2+ and Cu2+ simultaneously.•The sensor exhibited good stability, ultra-high sensitivity and acceptable reproducibility without any secondary pollution.

In this work, Zn(OH)2 nanosheets embedded with carbon dots (CDs) were prepared through a template-free microwave-assisted route for the first time. The preparative strategy was facile, green and cost-effective. The final composites possessed uniform size distribution, good fluorescence property, excellent stability and fast adsorption ability for metal ions. A novel and ultrasensitive fluorescent assay has been proposed using CDs/Zn(OH)2 composites as amplifying fluorescent sensors for rapid detection of Cu2+ and Hg2+ in real water samples. Aided by a Cu2+/Hg2+ chelating agent, exclusive detection could be expected without cross-reactivity, as well as reversible and reproduced analysis. The detection limits were 0.3 nM for Cu2+ and 0.2 nM for Hg2+, respectively. This assay could effectively enrich/separate and detect Hg2+ and Cu2+ simultaneously, revealing remarkable advantages including operational simplicity, high sensitivity, low cost and acceptable reproducibility.

Graphical abstractCDs/Zn(OH)2 composites were firstly prepared by a template-free microwave-assisted route and used for the separation and detection of Hg2+ and Cu2+ simultaneously.Figure optionsDownload full-size imageDownload as PowerPoint slide