Toward Detection of Formaldehyde on Copper Oxides Formed from Copper Iodide–Polypyrrole Composite

An approach of the preparation of catalysts based on copper oxide-polypyrrole (PPy) composites formed via electrooxidation of CuI–PPy layers on the surface of inert glassy carbon electrode was proposed. The pure CuI without polypyrrole matrix was used for comparison. The formation of CuO and the presence of CuO phase in electrooxidized samples was confirmed by EDX and XRD analysis correspondingly. Electrochemical properties of electrooxidized CuI–PPy composite (EOCP) were studied in formaldehyde and methanol oxidation reactions and compared with electrochemical properties of electrooxidized CuI (EOC) sample. Tests in methanol and in formaldehyde solutions confirmed the highest sensitivity of studied samples to formaldehyde. The linear detection range (LDR) of formaldehyde detection in alkaline solution for EOC system was 0–10 mM, the sensitivity was 125 ± 4 nA µg^–1 mM^–1, the detection limit was 15.9 ± 0.6 µM, while EOCP system demonstrated the extended LDR of 0–60 mM, the slightly lower sensitivity of 103 ± 0.5 nA µg^–1 mM^–1 but the lower detection limit of 7.3 ± 0.3 µM.