Highly sensitive electrochemical determination of chemical oxygen demand by carbon-capsulated CuOx derived from Cu foam supported Cu-MOF

Efficient detection of chemical oxygen demand (COD) is crucial for effective pollution prevention. Traditional Cu-based electrodes, widely utilized for COD sensors suffer from issues related to low activity and stability. This study introduced a novel approach by employing a copper foam-supported metal-organic frameworks (Cu-MOF), synthesized through a solvothermal method, which is subsequently pyrolyzed to yield a carbon-capsulated CuO_x/Cu foam electrode. Cyclic voltammetry analysis demonstrated that the carbon-capsulated CuO_x/Cu foam electrode exhibited superior redox activity, notably generating an increased amount of Cu(III) species. This enhancement significantly contributed to the electrocatalytic oxidation of organic compounds. The developed electrode demonstrated a wide linear detection range of 5–600 ppm, with a low detection limit of 0.96 ppm (S/N=3) for COD sensing. Notably, the sensor exhibited excellent anti-interference capabilities, desirable reproducibility, and stability. The proposed method was successfully applied to determine COD in real water samples. Comparative analysis with the standard potassium dichromate method revealed high accuracy and a low relative error (2.89 %–6.72 %). This innovative approach holds promise for rapid and accurate COD detection, presenting a valuable contribution to environmental monitoring and water quality assessment.