Zhen-Fan Sun

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.

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.