From 0D to 2D: N-doped carbon nanosheets for detection of alcohol-based chemical vapours

The application of N-doped carbon nanosheets, with and without embedded carbon dots, as active materials for the room temperature chemoresistive detection of methanol and/or ethanol is presented. The new carbons were made by converting 0D N-doped carbon dots (NCDs) to 2D nitrogen-doped carbon nanosheets by heat treatment (200-700 degrees C). The nanosheets exhibited a lateral size of similar to 3 mu m and a thickness of similar to 12 nm at the highest annealing temperature. Both Raman and TEM analyses showed morphological transitions of the dots to the sheets, whilst XPS analysis revealed transformation of the N-bonding states with increasing temperature. PDF analysis confirmed the presence of defective carbon sheets. Room temperature screening of the chemical vapours of two alcohols (methanol and ethanol), revealed that the structure and the type of N-configuration influenced the detection of the chemical vapours. For instance, the lateral size of the nanosheets and the high charge density N-configurations promoted detection of both methanol and ethanol vapours at good sensitivity (-16.8 x 10(-5) ppm(EtOH)(-1) and 1.2 x 10(-5) ppm(MeOH)(-1)) and low LoD (similar to 44 ppm(EtOH) and similar to 30.3 ppm(MeOH)) values. The study showed that the composite nature as well as the large basal area of the carbon nanosheets enabled generation of adequate defective sites that facilitated easy adsorption of the VOC analyte molecules, thereby eliminating the need to use conducting polymers or the formation of porous molecular frameworks for the alcohol detection.

Automated summary

This study presents the application of N-doped carbon nanosheets for room temperature chemoresistive detection of methanol and ethanol. The nanosheets were made by heat treatment of N-doped carbon dots and showed good sensitivity and low detection limits for both alcohols. The composite nature and large basal area of the nanosheets facilitated easy adsorption of the analyte molecules.