Carbon Quantum Dots: Dimethylglyoxime Thin Film-Based Chemosensors for the Specific Detection of Nickel Ions in Water Resources

This study presents the development of carbon quantum dot (CQDs)–dimethylglyoxime (DMG) thin film-based chemosensors for the sensitive and selective detection of nickel ions (Ni 2+ ) in water resources. These sensors leveraged a dual sensing strategy that combined optical and electrochemical techniques for enhanced accuracy and reliability. The CQDs-DMG thin film was characterized using various techniques, including ultraviolet–visible (UV-vis) spectroscopy, differential pulse voltammetry (DPV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The sensors demonstrated high sensitivity and selectivity toward Ni 2+ with low detection limits of 0.36 ppm (optical) and 0.29 ppm (electrochemical), achieving a rapid response within 1 min. Spike and recovery studies were conducted using real water samples from the Kshipra and Narmada Rivers, as well as tap water, demonstrating the sensor’s applicability in real-world scenarios. The sensor’s performance was validated by comparison with standard microwave plasma-mediated atomic emission spectroscopy (MP-AES) analysis, exhibiting over 95% accuracy. This innovative dual sensing platform offers a promising solution for the rapid, on-site, and point-of-care detection of Ni 2+ in water resources, contributing to improved environmental monitoring and management.