One-pot green synthesis of copper(I) iodide nanocrystallites using red cabbage extract and its application for the colorimetric sensing of elemental mercury vapor
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 Hg0 vapor through a smartphone camera-based digital image analysis. The sensor exhibited a colorimetric response to Hg0 vapor at a concentration range of 11.4–32.6 ppbv Hg0 with detection limit of 3.9 ppbv Hg0, indicating the capability of the sensor to detect the current threshold exposure limit set by the World Health Organization (6.1 ppbv). The sensor performance characteristics confirm that the green-synthesized CuI can be a suitable colorimetric sensitive layer for detection of Hg0 vapor.
Keywords: green chemistry, cuprous iodide, smartphone camera, colorimetric sensor, mercury vapor