In-situ synthesis of Cu2OAu nanocomposites as nanozyme for colorimetric determination of hydrogen peroxide

In this paper, gold nanoparticles-doped Cu 2 O cubes (Cu 2 O Au nanocomposites) with peroxide-like character were readily prepared through a simple two-step method and were used for sensitive readout of H 2 O 2 with color variation for the first time. By changing reaction temperature and feed rate, Cu 2 O nanocrystals with very small size were obtained and were then used to prepare Cu 2 O Au nanocomposites. HR-TEM, SEM, and XRD were used to characterize their morphology and size. The results revealed that the as-prepared Cu 2 O Au nanocomposites displayed rough cube morphology, with Cu 2 O cube, ca. 85 nm in size, filled with 8 nm spheres. In the presence of H 2 O 2 , 3,3,5′,5′-tetramethyl benzidine (TMB) was catalyzed by Cu 2 O Au nanocomposites and generated color changes, which was employed to detect H 2 O 2 . By comparison with Cu 2 O nanocrystals with different sizes, Cu 2 O 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 H 2 O 2 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.