Selective Determination of Copper (II) Based on Aluminum Silicon Carbide Nanoparticles Modified Glassy Carbon Electrode by Square Wave Stripping Voltammetry

Fabrication of Screen-Printed Electrodes Modified by Hydrothermal MnO2 Microflowers and Carbon for Electrochemical Sensors in Copper Ions Detection

Porous MnO2 microflowers with a hexagonal crystalline structure were facilely prepared at a low hydrothermal temperature of 90°C, without using any template or capping agent. The as-prepared MnO2 only presented an excellent detection ability for copper (II) by a square wave anodic stripping voltammetry in the presence of super P carbon black as conducting agent, and Nafion as binder. In the present work, to evaluate the detection ability of copper (II) in the MnO2 microflowers, chips of screen-printed electrodes (SPEs) having a polyurethane substrate, a silver working electrode, a carbon counter electrode, and a silver pseudoelectrode, were designed. Then, the SPEs chips were modified with MnO2 microflowers and/or super P carbon and used as electrochemical sensors for the detection of copper (II) present in water sources. From the measured results, the fabricated sensors with excellent copper detection in a linear range from 0.625 nM to 15 nM (R2 = 0.9737), and a low detection limit (0.5 nM), high sensitivity (214.05 μA/cm2 nM), and rapid response (180 s) demonstrated high application potential for electrochemical sensors in the detection of copper in water resources.

A double-potential ratiometric electrochemiluminescence platform based on g-C3N4 nanosheets (g-C3N4 NSs) and graphene quantum dots for Cu2+ detection

A new kind of convenient, low-cost double-potential ratiometric ECL sensing platform for the quantification of Cu²⁺ was developed with carbon nitride nanosheets (g-C₃N₄ NSs) and graphene quantum dots (GQDs) as ECL luminophores. g-C₃N₄ NSs mixed with multi-walled carbon nanotubes (MWCNTs) was immobilized on a glass carbon electrode (GCE) and produced strong cathodic ECL at a potential of -1.2 V (vs. Ag/AgCl), while GQDs in the solution gave anodic ECL at +2.5 V. MWCNTs were used here to amplify the ECL signal of g-C₃N₄ NSs. The addition of Cu²⁺ causes the cathodic ECL signal from g-C₃N₄ to decline, while the anodic ECL signal from GQDs remains unchanged. With the anodic ECL signal as an internal reference, a double-potential ratiometric ECL sensing platform for Cu²⁺ was established. The ratio of the cathodic signal intensity to anodic signal intensity showed a linear response to the Cu²⁺ concentration over a range from 5.0 × 10^-10 to 1.0 × 10^-6 mol L^-1 and the detection limit was 0.37 nmol L^-1 (3σ/S). Such a construction strategy alleviates the interference from the environment and therefore improves the detection accuracy of Cu²⁺. Compared with other methods for Cu²⁺ detection, this method is simpler and more sensitive.