Bingxin Lei

Application of graphene-copper sulfide nanocomposite modified electrode for electrochemistry and electrocatalysis of hemoglobin.

In this paper a graphene (GR) and copper sulfide (CuS) nanocomposite was synthesized by hydrothermal method and used for the electrode modification with a N-butylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) as the substrate electrode. Hemoglobin (Hb) was immobilized on the modified electrode to get a biocompatible sensing platform. UV-vis absorption spectroscopic results confirmed that Hb retained its native secondary structure in the composite. Direct electron transfer of Hb incorporated into the nanocomposite was investigated with a pair of well-defined redox waves appeared on cyclic voltammogram, indicating the realization of direct electrochemistry of Hb on the modified electrode. The results can be ascribed to the presence of GR-CuS nanocomposite on the electrode surface that facilitates the electron transfer rate between the electroactive center of Hb and the electrode. The Hb modified electrode showed excellent electrocatalytic activity to the reduction of trichloroacetic acid in the concentration range from 3.0 to 64.0 mmol L(-1) with the detection limit of 0.20 mmol L(-1) (3σ). The fabricated biosensor displayed the advantages such as high sensitivity, good reproducibility and long-term stability.

Fabrication of graphene-platinum nanocomposite for the direct electrochemistry and electrocatalysis of myoglobin

In this paper a platinum (Pt) nanoparticle decorated graphene (GR) nanosheet was synthesized and used for the investigation on direct electrochemistry of myoglobin (Mb). By integrating GR-Pt nanocomposite with Mb on the surface of carbon ionic liquid electrode (CILE), a new electrochemical biosensor was fabricated. UV-Vis absorption and FT-IR spectra indicated that Mb remained its native structure in the nanocomposite film. Electrochemical behaviors of Nafion/Mb-GR-Pt/CILE were investigated with a pair of well-defined redox peak appeared, which indicated that direct electron transfer of Mb was realized on the underlying electrode with the usage of the GR-Pt nanocomposite. The fabricated electrode showed good electrocatalytic activity to the reduction of trichloroacetic acid in the linear range from 0.9 to 9.0 mmol/L with the detection limit as 0.32 mmol/L (3σ), which showed potential application for fabricating novel electrochemical biosensors and bioelectronic devices.

Simultaneous electrochemical determination of guanosine and adenosine with graphene–ZrO2 nanocomposite modified carbon ionic liquid electrode

In this paper an ionic liquid 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) was fabricated and used as the basal electrode, which was further modified by graphene (GR) and ZrO2 nanoparticle with chitosan (CTS) film to immobilize the nanocomposite. The modified electrode was denoted as CTS-GR-ZrO2/CILE and further used for the simultaneous detection of adenosine and guanosine. Electrochemical performances of the modified electrode were greatly enhanced due to the presence of GR-ZrO2 nanocomposite, and the direct electro-oxidation behaviors of adenosine and guanosine were carefully investigated. Both adenosine and guanosine exhibited an increase of the oxidation peak currents with the negative shift of the oxidation peak potentials on the modified electrode, which indicated the electrocatalytic activity of GR-ZrO2 nanocomposite on the electrode surface. Electrochemical parameters of adenosine and guanosine on CTS-GR-ZrO2/CILE were calculated respectively, and a new electroanalytical method for the simultaneous determination of adenosine and guanosine was further established with the peak-to-peak separation (ΔEp) as 0.225V. The proposed method was successfully applied to detect adenosine and guanosine in human urine samples with satisfactory results.

Hierarchically porous N–F codoped TiO2 hollow spheres prepared via an in situ bubbling method for dye-sensitized solar cells

Hierarchically porous N–F codoped TiO2 hollow spheres with a diameter of 0.8–1.8 μm and shell thickness of 250 nm are synthesized via an in situ bubbling method. Although the photoelectrode film constructed with the hierarchically porous N–F codoped TiO2 hollow spheres possesses a lower specific surface area than that of P25 nanocrystallites and thus achieves less dye adsorption, it may generate effective light scattering and therefore enhance the light harvesting efficiency, leading to higher power conversion efficiency (6.59%). The double layered DSSC with the hierarchically porous N–F codoped TiO2 hollow spheres as the top layer and P25 as the bottom layer is constructed and a 7.36% solar energy conversion efficiency is demonstrated, indicating a 10% improvement compared with the P25 cell of 6.65%. The improved photovoltaic performance of the double layered DSSC is primarily due to the effective suppression of the back reaction of the injected electron with the I3− in the electrolyte by decreasing the surface charge trap-site density of the photoanode and excellent light scattering ability.