Coral-like CeO2/NiO nanocomposites with efficient enzyme-mimetic activity for biosensing application.

Development of nanomaterials-based enzymatic mimics has gained considerable attention in recent years, because of their low cost, high stability and efficiently catalytic ability. Here, CeO2 was successfully incorporated into the coral-like NiO nanostructures assembled by nanoflakes with high surface area, forming the coral-like CeO2/NiO nanocomposites. The morphology and composition of CeO2/NiO nanocomposites were characterized by XRD, SEM, element mapping and XPS. The results of characterization showed that cerium was highly dispersed in the coral-like NiO nanostructures. The peroxidase-like activity of CeO2/NiO nanocomposites was investigated, and they exhibited enhanced peroxidase-like activity in comparison to that of pure NiO or CeO2. The catalytic activity was dependent on the cerium content, and the optimal content was 2.5%. The enhanced catalytic activity of CeO2/NiO nanocomposites arised from their high ability of electron transfer because of cerium incorporation. The catalytic performance of CeO2/NiO nanocomposites was evaluated by steady-state kinetic, which showed that the CeO2/NiO nanocomposites exhibited higher affinity for the substrates and similar catalytic efficiency compared with natural peroxidase. Based on the efficient peroxidase-like activity, CeO2/NiO was used for H2O2 determination. The constructed colorimetric H2O2 sensor had fast response for only 5min, a wide linear range from 0.05 to 40mM and a low detection limit with 0.88µM. The CeO2/NiO nanocomposites were expected to have potential applications in clinical diagnosis and biotechnology as enzymatic mimics.