Development of 2D Ir-DMG nanosheets as a colorimetric sensor probe for Ni (II) sensing and a highly sensitive, reliable, and portable colorimetric sensor device for environmental analysis

The era of nanomaterials made a revolutionary change in colorimetric sensing with ultra-high sensitivity, improved reactivity, and enhanced photoactivity. The first-ever novel 2D metal–organic nanosheets were synthesized using IrCl₃ and Dimethylglyoxime (DMG) by probe ultrasonication (PUS) followed by a solvothermal wet-chemical approach. This material has shown a rapid color change from yellow to crimson red with Ni (II) after the formation of complex. The UV–visible absorption spectra are the conventional methodology for colorimetric sensors and here, it was given a perfect linear relationship with an R² of 0.99 and an LOD of 1.60 µM (0.1 ppm). The average calculated molar extinction coefficient for this system was 1889.30 M⁻¹ cm⁻¹. This is comparatively high absorptivity value. In addition, a novel Arduino-based colorimetric sensor device and corresponding software were developed under the name of “Chrom Metrics”. This Arduino device is unique since it can sense all wavelengths and the combined RGB delta E values. Therefore, it can provide more information/rationale for colorimetry than other devices/methods. The same Ir-DMG & Ni (II) system showed a perfect linear relationship with an R² of 0.98 and a LOD of 0.85 µM (0.05 ppm) by the data obtained from this sensor device. Thus, this new device is easier and more accurate, highly efficient, rapid, highly selective, and sensitive.