Electrochemical activation of copper oxide decorated graphene oxide modified carbon paste electrode surface for the simultaneous determination of hazardous Di-hydroxybenzene isomers

The construction of a consistent electrochemical sensor is essential for the determination of hazardous pollutants in water and environments. Hydroquinone (HQ), catechol (CT), and resorcinol (RS) frequently coexist as priority pollutants in water and interfere with each other during identification, which poses a challenge for simultaneous and sensitive determination for those di-hydroxybenzene isomers. In this work, copper oxide (CuO) decorated graphene oxide (GO) nanocomposite (CuO/GO) was prepared and used to modify carbon paste electrode (CPE). The as-prepared electrode (CGCPE) was electrochemically activated in the presence of NaOH solution (Et-CGCPE) for the simultaneous determination of di-hydroxybenzene isomers (HQ, CT, and RS), and showed a well-defined oxidation peak with a significantly improved electrochemical response. We ascribe this high performance to the formation of electroactive functional groups on the electrode surface during the electrochemical activation and the synergistic effect between GO and CuO. Under the optimized conditions, the results show a long linear concentration range of HQ (0.2-360 mu M), CT (0.3-360 mu M), and RS (0.7-250 mu M) with the detection limits of 1.0 mu M, 1.1 mu M, and 1.8 mu M, respectively. The Et-CGCPE was effectively applied to detect three di-hydroxybenzene isomers in lake water with good repeatability and stability.