A nickel nanoparticle/nafion-graphene oxide modified screen-printed electrode for amperometric determination of chemical oxygen demand

A nickel nanoparticle/nafion-graphene oxide (NiNP/Nf-GO) modified screen-printed electrode (SPE) was developed for rapid and environmentally friendly electrochemical determination of chemical oxygen demand (COD). The morphology and the electrochemical performance of the SPEs with different surface modifications were investigated by scanning electron microscopy, electrochemical impedance spectroscopy, amperometry, and cyclic voltammetry, respectively. Interestingly, incorporation of graphene oxide as supporting materials to the NiNP/Nf-GO modified SPE enables high catalyst loading and electrode contact, leading to excellent electrocatalytic oxidation ability. A flow detection system was constructed based the newly designed NiNP/Nf-GO modified SPE with USB connection, a 3D-printed thin-layer flow cell (TLFC), and a peristaltic pump. The flow detection system showed an excellent performance for COD analysis with a linear detection range of 0.1~400 mg L−1 and a lower detection limit of 0.05 mg L−1 with an oxidation potential of 0.45 V. The system was further applied to determine the COD in surface water samples. The results were consistent with those obtained by using the standard method (ISO 6060).