Xiaoyong Lai

3D NiO hollow sphere/reduced graphene oxide composite for high-performance glucose biosensor

The 3D NiO hollow sphere/reduced graphene oxide (rGO) composite was synthesized according to the coordinating etching and precipitating process by using Cu2O nanosphere/graphene oxide (GO) composite as template. The morphology, structure, and composition of the materials were characterized by SEM, TEM, HRTEM, XPS, and Raman spectra, and the electrochemical properties were studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry. Moreover, the electrochemical activity of the composite materials with different morphologies were also investigated, which indicating a better combination of the NiO hollow sphere and the rGO. Used as glucose sensing material, the 3D NiO hollow sphere/rGO composite modified electrode exhibits high sensitivity of ~2.04 mA mM−1 cm−2, quick response time of less than 5 s, good stability, selectivity, and reproducibility. Its application for the detection of glucose in human blood serum sample shows acceptable recovery and R.S.D. values. The outstanding glucose sensing performance should be attributed to the unique 3D hierarchical porous superstructure of the composite, especially for its enhanced electron-transfer kinetic properties.

Rapid synthesis of rGO conjugated hierarchical NiCo2O4 hollow mesoporous nanospheres with enhanced glucose sensitivity

NiCo2O4 nanospheres, a type of conjugated reduced graphene oxide (rGO), are compounded by a simple and easy synthesis of Cu2O/GO and fabricated NiCo2O4/rGO nanocomposites based on a Cu2O/GO template. The structure and morphology of the hierarchical NiCo2O4/rGO are characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electrochemistry properties of NiCo2O4/rGO composites toward glucose are determined based on a glassy carbon electrode, and the results indicate that the hollow nanospheres of NiCo2O4/rGO could achieve high-sensitivity detections of glucose. The NiCo2O4/rGO composite has a detection range of 0.04 mM to 1.28 mM, a sensitivity of 2082.57 μA mM-1 cm-2, and a detection limit of 0.7 μM. The composite further exhibits obvious stability, superior reproducibility, and excellent selectivity. This study demonstrates that NiCo2O4/rGO is a unique and material with high potential in glucose sensing.

Hierarchical NiCo2O4 Hollow Sphere as a Peroxidase Mimetic for Colorimetric Detection of H2O2 and Glucose

In this work, the hierarchical NiCo2O4 hollow sphere synthesized via a “coordinating etching and precipitating” process was demonstrated to exhibit intrinsic peroxidase-like activity. The peroxidase-like activity of NiCo2O4, NiO, and Co3O4 hollow spheres were comparatively studied by the catalytic oxidation reaction of 3,3,5,5-tetramethylbenzidine (TMB) in presence of H2O2, and a superior peroxidase-like activity of NiCo2O4 was confirmed by stronger absorbance at 652 nm. Furthermore, the proposed sensing platform showed commendable response to H2O2 with a linear range from 10 μM to 400 μM, and a detection limit of 0.21 μM. Cooperated with GOx, the developed novel colorimetric and visual glucose-sensing platform exhibited high selectivity, favorable reproducibility, satisfactory applicability, wide linear range (from 0.1 mM to 4.5 mM), and a low detection limit of 5.31 μM. In addition, the concentration-dependent color change would offer a better and handier way for detection of H2O2 and glucose by naked eye.

Size-Controlled Silver Nanoparticles Confined in Ordered Mesoporous Silica and Their Enhanced Catalytic Activities

A cooperative assembly route has been developed, by which silver nanoparticles with controlled sizes are incorporated into the channels of ordered cubic mesoporous silica (KIT-6) with different pore sizes (4.3–6.4nm). The samples were characterized by XRD, TEM, FT-IR, UV-Vis and N2 physisorption. The pore wall of mesoporous silica can efficiently confine the growth of silver nanoparticles within the channels and their average sizes decreased with the pore size reduction of KIT-6. Catalytic activities of the resultant Ag/KIT-6-x (x stands for hydrothermal temperature) composite for reducing harmful organic dye Rhodamine B (Rh B) by sodium borohydride (NaBH4) were investigated. All the Ag/KIT-6 composite samples show great catalytic activities, among which Ag/KIT-6-80 with higher loading and smaller size of Ag nanoparticles exhibits higher catalytic activity than those of Ag/KIT-6-60 and Ag/KIT-6-100.