Cobalt and zinc imidazolate encapsulated in reduced graphene oxide and the derived nitrogen-enriched carbon frameworks (CoNC@rGO) for electrochemically sensing acetaminophen (APAP)

Electrochemical detection of the analgesic acetaminophen (APAP) was carried out using a composite of cobalt and zinc imidazolate frameworks and graphene oxie (Co/ZnZIF@GO). Co/ZnZIF@GO was thermally reduced to create cobalt/nitrogen-enriched carbon and reduced graphene oxide (CoNC@rGO), which greatly facilitated the current response for APAP sensing. The mesoporosity of NC cubes embedded in rGO sheets and the dispersity of Co nanoparticles were manipulated by the carbonization temperature. Electroanalysis and Raman spectra revealed that the reversible conversion of phenolic hydroxyl to ketone in the doubly chelated APAP on surface Co sites accounted for the faradaic current of APAP oxidation. CoNC@rGO(800), synthesized at 800 °C under a N2 atmosphere, with an optimal metal ratio of Co0.5Zn0.5 and 50 % GO loading maximized electrode sensitivity. This resulted in a high sensitivity (0.598 μA μM−1) and a low detection limit (0.067 μM) in the range of 0.5–50 μM. Through the differential pulse voltammetry technique (DPV), the synthesized sensor exhibited excellent reproducibility, selectivity, and recovery for detecting APAP in various real-world water samples.