2,2′-Biquinoline Modified Expanded Graphite Electrode for the Detection of Cuprous Ions in Electrolytic Copper Foil Electrolyte

The coexistence of Cu in copper sulfate electrolyte significantly affects the microstructure and performance of the copper foil. So far, there has been little quantitative analysis of Cu⁺ in the electrolyte during the copper foil production process. This paper fabricated a 2,2'-Biquinoline (BIQ) modified expanded graphite (EG) electrode electrochemical sensor for the selective determination of Cu⁺. EG, with its large specific surface area and excellent adsorption and electrochemical properties, significantly enhances analytical sensitivity. Additionally, BIQ's specific coordination with Cu⁺ improves the sensor's rapid and effective quantification of Cu⁺ in the electrolytic copper foil electrolyte. The linear equation of this sensor is I = 0.03769 + 0.29997 × c (R² = 0.9989), with a detection limit of 8 μg/L (S/N = 3). The BIQ-modified EG electrode has good selectivity for Cu⁺, with a recovery rate for cuprous ions of 101.00% to 105.00% under the coexistence of 10,000 times Cu²⁺, and an RSD of less than 2%. This sensor's efficient, sensitive, and selective detection of Cu⁺ can be an effective method to improve the quality of electrolytic copper foil products.