Jinhui Hao

Protein as the source for synthesizing fluorescent carbon dots by a one-pot hydrothermal route

Fluorescent carbon dots (C-dots) are prepared directly via a simple hydrothermal method using bovine serum albumin (BSA) as a carbon source in the presence of surface passivation reagents. The obtained C-dots have low cytotoxicity and good biocompatibility, demonstrating that their features are good for application in cell imaging.

Porous Co3O4 Nanorods–Reduced Graphene Oxide with Intrinsic Peroxidase-Like Activity and Catalysis in the Degradation of Methylene Blue

A facile two step process was developed for the synthesis of porous Co3O4 nanorods-reduced graphene oxide (PCNG) hybrid materials based on the hydrothermal treatment cobalt acetate tetrahydrate and graphene oxide in a glycerol-water mixed solvent, followed by annealing the intermediate of reduced graphene oxide-supported Co(CO3)0.5(OH)·0.11H2O nanorods in a N2 atmosphere. The morphology and microstructure of the composites were examined by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and Raman spectroscopy. It is shown that the obtained PCNG have intrinsic peroxidase-like activity. The PCNG are utilized for the catalytic degradation of methylene blue. The good catalytic performance of the composites could be attributed to the synergy between the functions of porous Co3O4 nanorods and reduced graphene oxide.

In situ controllable growth of CoFe2O4 ferrite nanocubes on graphene for colorimetric detection of hydrogen peroxide

A facile method is proposed for the synthesis of cubic CoFe2O4 ferrite–reduced graphene oxide nanocomposite sheets (rGO–CFs), using poly(N-vinyl-2-pyrrolidone) as the reductant and stabilizer. The rGO–CFs functioned as efficient peroxidase mimetics and were successfully applied for colorimetric assay. The morphology and composition of the rGO–CFs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Significantly, the peroxidase-like activity of the rGO–CFs followed typical Michaelis–Menten kinetics and showed a good affinity to 3,3,5,5-tetramethyl benzidine. Under optimum conditions, the colorimetric assay showed a lower detection limit (S/N = 3) of 0.3 μM when compared with that of other nanoparticle based colorimetric assays. Furthermore, the cubic nanostructured rGO–CFs exhibited better stability than horseradish peroxidase when they were exposed to solutions with different solvents and temperatures. These excellent properties made the cubic nanostructured rGO–CFs an ideal candidate for a wide range of potential applications as peroxidase mimetics.

Defect-Rich CoP/Nitrogen-Doped Carbon Composites Derived from a Metal–Organic Framework: High-Performance Electrocatalysts for the Hydrogen Evolution Reaction

A defect‐rich CoP/nitrogen‐doped carbon composite is reported for the first time derived from ZIF‐67 by means of low‐temperature phosphidation process. As a hydrogen evolution reaction electrocatalyst, the obtained CoP‐N‐C has high HER activity and good stability with a low onset overpotential of 31 mV, a small Tafel slope of 42 mV dec−1, a large exchange current density of 1.6×10−1 mA cm−2, and a 10 mA cm−2 current density at overpotential 91 mV.

Iron triad (Fe, co, Ni) trinary phosphide nanosheet arrays as high-performance bifunctional electrodes for full water splitting in basic and neutral conditions

The development of an efficient and affordable bifunctional electrode for full water splitting in basic and neutral conditions is still a challenging issue in obtaining clean and sustainable chemical fuels. Herein, a unique bifunctional electrode consisting of 3D trinary transition-metal phosphide nanosheets with abundant reactive sites anchored on Ni foam, referred to as FexCoyNizP, has been developed through a facile two-step process of electrodeposition and low-temperature phosphidation. When used as a bifunctional electrode for the full water splitting, an applied voltage of 1.57 V is required for a current density of 10 mA cm−2.

One-pot solvothermal synthesis of graphene-supported TiO2 (B) nanosheets with enhanced lithium storage properties

A facile process was developed for the synthesis of graphene-supported TiO2 (B) nanosheets (GTBN) composite based on the hydrothermal treatment titanium (III) chloride and graphene oxide in an ethylene glycol. The morphology and microstructure of the composites were examined by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and Raman spectroscopy. The obtained GTBN show a high thermal stability and the phase transformation of TiO2 (B) to anatase can be prevented by graphene after pyrolysis of GTBN at 350°C for 2h. Furthermore, GTBN exhibited high rate performance and stability of lithium ion batteries, due to the enhanced conductivity of the electrode and accommodation to volume/strain changes during lithium insertion-extraction.

PB@Co3O4 nanoparticles as both oxidase and peroxidase mimics and their application for colorimetric detection of glutathione

Co3O4-modified Prussian blue (PB) nanocubes (PB@Co3O4) were prepared by a simple water-bath method with CoCl2 as the Co source. TEM, SEM, XRD and XPS results indicated the uniform distribution of island-like spinel-phase Co3O4 nanoparticles (NPs) on the surfaces of the PB nanocubes (∼200 nm). The PB@Co3O4 NPs exhibited both intrinsic oxidase- and peroxidase-like activities and were observed to rapidly oxidize the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) with or without hydrogen peroxide at acidic pH values. In contrast, PB nanocubes or Co3O4 NPs alone could not efficiently oxidize TMB without H2O2. The enzyme-like activity of PB@Co3O4 NPs was also influenced by the working pH and temperature. Based on the oxidase-like activity of PB@Co3O4 NPs, a facile colorimetric biosensor for detection of glutathione was successfully fabricated, and displayed a linear range of 0.1 to 10 μM (R = 0.9740) and limit of detection of 0.021 μM (S/N = 3). These results demonstrate the potential applications of PB@Co3O4 NPs in bioanalysis and biodetection.

Facile synthesis of Au@Fe3O4–graphene and Pt@Fe3O4–graphene ternary hybrid nanomaterials and their catalytic properties

Graphene-based sheets that possess a unique nanostructure and a variety of fascinating properties are appealing as promising nanoscale building blocks of new composites. Herein, we present a general and effective approach for the preparation of metal oxide–graphene (metal oxide–G, metal oxide = Fe3O4, ZnO and Cu2O) by in situ nucleation and growth of metal oxide on the surface of graphene in tetraethylene glycol (TEG) solution. TEG, a nontoxic and environmentally friendly agent, acts as both solvent and reductant. Furthermore, the Fe3O4–G was employed as a two dimensional support for loading noble metal nanoparticles (Au or Pt) to synthesize Au@Fe3O4–G and Pt@Fe3O4–G ternary hybrid materials. The as-obtained Au@Fe3O4–G exhibited excellent catalytic activity in the reduction of 4-nitrophenol by NaBH4, and the Pt@Fe3O4–G showed remarkable electrocatalytic performance for hydrazine oxidation. We believe that the hybrid catalysts fabricated by this simple, efficient method have great potential for applications in other fields, such as electrochemical energy storage, sensors, and so on.

Single molecular recognition force spectroscopy study of a DNA aptamer with the target epithelial cell adhesion molecule

The epithelial cell adhesion molecule (EpCAM) is a tumor-specific antigen for malignancies of the epithelialis lineage. In this study the interaction between the DNA-based EpCAM aptamer (SYL3C) and EpCAM was explored using single molecular recognition force spectroscopy (SMFS). The capability of aptamer SYL3C to recognize the EpCAM protein and the kinetic parameters were investigated.

Facile synthesis of three dimensional hierarchical Co-Al layered double hydroxides on graphene as high-performance materials for supercapacitor electrode.

A facile simple hydrothermal method combined with a post-solution reaction is developed to grow interconnected three dimensional (3D) hierarchical Co-Al layered double hydroxides (LDHs) on reduced graphene oxide (rGO). The obtained 3D hierarchical rGO-LDHs are characterized by field emission scanning electron microscopy, X-ray diffraction, and X-ray photo-electron spectroscopy. As LDHs nanosheets directly grow on the surface of rGO via chemical covalent bonding, the rGO could provide facile electron transport paths in the electrode for the fast Faradaic reaction. Moreover, benefiting from the rational 3D hierarchical structural, the rGO-LDHs demonstrate excellent electrochemical properties with a combination of high charge storage capacitance, fast rate capability and stable cycling performance. Remarkably, the 3D hierarchical rGO-LDHs exhibit specific capacitance values of 599 F g(-1) at a constant current density of 4 A g(-1). The rGO-LDHs also show high charge-discharge reversibility with an efficiency of 92.4% after 5000 cycles.