A nano-copper electrochemical sensor for sensitive detection of chemical oxygen demand

Copper nanoparticle (nano-Cu) was electrodeposited on the surface of Cu disk electrode under −1 V for 60 s, and then used to construct an electrochemical sensor for chemical oxygen demand (COD). The electrochemical oxidation behavior of glycine, a standard compound for evaluating the COD, was investigated. The potential shifts negatively, and the current increases greatly at the surface of nano-Cu, indicating remarkable enhancement effect on the detection of COD. The analytical conditions such as electrolyte, deposition potential, deposition time and detected potential were studied. As a result, a sensitive, simple and rapid electroanalytical method was developed for COD using amperometric detection. The linear range is from 4.8 to 600 mg L⁻¹, and the limit of detection is as low as 3.6 mg L⁻¹. Moreover, this method exhibits high tolerance level to chloride ion, and 0.02 M chloride ion has no influence. Finally, the sensor was used to detect the COD values of different water samples, and the results were testified by the standard dichromate method.