Synthesis of Ni–TiO2 Nanocomposites as Enzyme–Less, Amperometric Sensors for the Electrooxidation of Glucose

Abstract

The simple synthesis of a Ni–TiO _2 nanocomposite supported on Vulcan carbon (XC–72 R) for the electrooxidation reaction of glucose is reported. Four transition metal weight ratios were synthesized and characterized. Cyclic voltammetry studies in 0.1 M NaOH demonstrate that the four metal catalysts can effectively oxidize 1 mM glucose, with the 3:1 (60%) Ni to Ti nanocomposite yielding the highest current. The 60% Ni–TiO _2 /XC72R catalyst was used to construct an enzyme–less, chronoamperometric sensor for glucose detection in an alkaline medium. Using 50 μ M aliquots of glucose at a potential of +0.7 V (vs Hg/HgO), the sensor responded rapidly (<3 s), provided a sensitivity of 3300 μ A mM ^−1 cm ^−2 , detection limits of 144 nM (Signal/Noise = 3), and excellent selectivity and reproducibility. The glucose aliquot concentrations were then increased to 1 mM to mimic physiological blood conditions of 1–20 mM. At a potential of +0.7 V (vs Hg/HgO), the sensor continued to respond rapidly (<1 s), showed a sensitivity of 273.7 μ A mM ^−1 cm ^−2 , detection limits of 3.13 μ M (S/N = 3), and excellent selectivity and reproducibility. The catalyst also exhibited an ideal anti–poisoning capability to free chloride ions and negligible signals towards other interfering species.