In-situ synthesis of Cu2O Au nanocomposites as nanozyme for colorimetric determination of hydrogen peroxide

Abstract In this paper, gold nanoparticles-doped Cu2O cubes (Cu2O Au nanocomposites) with peroxide-like character were readily prepared through a simple two-step method and were used for sensitive readout of H2O2 with color variation for the first time. By changing reaction temperature and feed rate, Cu2O nanocrystals with very small size were obtained and were then used to prepare Cu2O Au nanocomposites. HR-TEM, SEM, and XRD were used to characterize their morphology and size. The results revealed that the as-prepared Cu2O Au nanocomposites displayed rough cube morphology, with Cu2O cube, ca. 85 nm in size, filled with 8 nm spheres. In the presence of H2O2, 3,3,5′,5′-tetramethyl benzidine (TMB) was catalyzed by Cu2O Au nanocomposites and generated color changes, which was employed to detect H2O2. By comparison with Cu2O nanocrystals with different sizes, Cu2O Au nanocomposites exhibited highest peroxide-like activity, which relies heavily on the pH and temperature in the reaction systems and satisfies with the Michaelis-Menten kinetics. Based on these findings, a colorimetric method was developed to detect H2O2 over a range between 0.4 μM and 1000 μM. This platform extends a great prospect in the field of clinical diagnosis, food safety, and environmental monitoring.