A highly uniform CuO@SiO2 porous sphere with improved electrochemical sensing performance for the accurate determination of vanillin in food samples

Abstract

A porous sphere of CuO@SiO2 was obtained by simple calcination of the copper silicate (CuSiO3) sphere. The formation of the porous sphere was studied in detail with the support of various physical characterization techniques. The CuO@SiO2 was coated on an electrode surface where it demonstrates high catalytic activity for the electro-oxidation of vanillin in phosphate buffer solution (PBS; pH 7.0). The modified electrode has good surface adsorption (1.861 × 10−10 mol cm−2) and rate constant (2.866 × 105 cm3 mol−1 s−1) characteristics for vanillin detection. The CuO@SiO2-modified surface exhibited good linear range (0.05 μM–1.2 μM and 6.2 to 111.2 μM), detection limit (53 nM), sensitivity (2.88 μA μM−1 cm−2), selectivity, stability, and reproducibility. The CuO@SiO2-modified electrode was further examined for the determination of vanillin in real samples including biscuits and chocolates with satisfactory recoveries.