Hydrothermal synthesis of CuO micro-/nanostructures and their applications in the oxidative degradation of methylene blue and non-enzymatic sensing of glucose/H2O2

Abstract

In this paper, we report on the amino acids-/citric acid-/tartaric acid-assisted morphologically controlled hydrothermal synthesis of micro-/nanostructured crystalline copper oxides (CuO). These oxides were characterized by means of X-ray diffraction, nitrogen sorption, scanning electron microscopy, Fourier transform infrared, and UV–visible spectroscopy. The surface area of metal oxides depends on the amino acid used in the synthesis. The formation mechanisms were proposed based on the experimental results, which show that amino acid/citric acid/tartaric acid and hydrothermal time play an important role in tuning the morphology and structure of CuO. The catalytic activity of as-synthesized CuO was demonstrated by catalytic oxidation of methylene blue in the presence of hydrogen peroxide (H2O2). CuO synthesized using tyrosine was found to be the best catalyst compared to a variety of CuO synthesized in this study. CuO (synthesized in this study)-modified electrodes were used for the construction of non-enzymatic sensors, which displayed excellent electrocatalytic response for the detection of H2O2 and glucose compared to conventional CuO. The high electrocatalytic response observed for the CuO synthesized using tyrosine can be correlated with the large surface area, which enhances the accessibility of H2O2/glucose molecule to the active site that results in high observed current. The methodology adopted in the present study provides a new platform for the fabrication of CuO-based high-performance glucose and other biosensors.