A hybrid system of carbon nanotubes(CNTs)coated with poly(amidoamine)(PAMAM)dendrimerencapsulated platinum nanoparticles(Pt-DENs)and glucose oxidase(GOx)was prepared through the layer-by-layer(LbL)self-assembly approach and then used as anode in enzyme-based biofuel cells(BFCs). The assembly process was monitored by-potential measurement,and the as-resulted Pt-DENs/CNTs nanocomposites were characterized by transmission electron microscopy(TEM).The performance of electrodes modified by Pt-DENs/CNTs was also investigated by electrochemical impedance spectroscopy (EIS)and cyclic voltammetry(CV).We found that the Pt-DENs/CNTs could enhance the electron transfer between the redox centers in enzyme and the electrode surfaces.Furthermore,by employing the Pt-DENs/CNTs modified electrodes as anode,the enzyme-based BFCs operated in a solution containing glucose generated an open-circuit voltage of approximately 640.0 mV and a maximum current density of about 90.0 A/cm2,suggesting that Pt-DENs/CNTs may serve as an alternative anode to previously used noble metals in BFC applications.
Jianmei ZhangYihua ZhuCheng ChenXiaoling YangChunzhong Li
A one-step method for continuous large-scale synthesis of well-defined hollow titania spheres was established by feeding titanium tetrachloride mixed with ethanol vapor to a facile diffusion fiame. A mixture of TiCl4 and C2H5OH vapor was transported at 100 m/s into a fiame reactor and condensed into mesoscale droplets due to Joule-Thomson cooling and the entrainment of cool gases into the expanding high-speed jet. Hollow crystalline TiO2 spheres with good thermal stability were formed after the hydrolysis of TiCl4 in the H2/air fiame at about 1500 fiC. Structural characterization indicates that the hollow spheres, with uniform diameter of 300 nm and shell thickness of 35 nm, consist of 20-30 nm TiO2 nanocrystallites. A formation mechanism of the hollow spheres was proposed, involving the competition between chemical reaction and diffusion during the fiame process. The present study provides a new pathway for continuous and large-scale engineering of hollow nanomaterials.
