One-pot green synthesis of copper(I) iodide nanocrystallites using red cabbage extract and its application for the colorimetric sensing of elemental mercury vapor

Abstract

CuI nanocrystallites were synthesized via a red cabbage-mediated one-pot method at ambient temperature. Red cabbage extract functioned as reducing agent, converting Cu(II) into Cu(I) and as a capping agent stabilizing the CuI nanocrystallites. The resulting material was characterized using X-ray powder diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, and UV-Vis spectroscopy. It was also characterized as a solid-state colorimetric sensing reagent for elemental Hg 0 vapor through a smartphone camera-based digital image analysis. The sensor exhibited a colorimetric response to Hg 0 vapor at a concentration range of 11.4-32.6 ppb v Hg 0 with detection limit of 3.9 ppb v Hg 0 , indicating the capability of the sensor to detect the current threshold exposure limit set by the World Health Organization (6.1 ppb v). The sensor performance characteristics confirm that the green-synthesized CuI can be a suitable colorimetric sensitive layer for detection of Hg 0 vapor.