RESUMEN

Graphitic multi-walled carbon nanotubes (MWCNTs) can function as high-performance cathode materials for rechargeable Al-ion batteries with well-defined discharging plateaus and reasonable charge/discharge C-rates. However, the main intercalation/deintercalation or adsorption/desorption path of AlCl4- anions into or onto G-MWCNTs has not been elucidated. Herein, we used battery cells comprised of G-MWCNTs with different aspect ratios, Al metal, and AlCl3/1-ethyl-3-methylimidazolium chloride ionic liquid as the cathode, anode, and electrolyte, respectively. The electrochemical performance of the Al||G-MWCNT cell increased as the aspect ratio of the G-MWCNT cathode increased (i. e., longer and thinner). The degree of defects of the G-MWCNTs was similar (0.15-0.22); hence, the results confirm that the main and alternate paths for the AlCl4- intercalation/de-intercalation or adsorption/desorption into/from or onto/from the G-MWCNT are the basal and edge planes, respectively. The step-like structures of defects on the basal plane provide the main reaction site for AlCl4- anions.

RESUMEN

In this work, cage-like ZrO2 and hollow ZrO2 microspheres with high surface area and strong adsorption capability were successfully synthesized by microwave- ethanol-thermal method using yeasts as bio-template. XRD, SEM, EDS and BET were used to characterize the products. The results show that these micropheres have a size of about 2-3 microm and are composed by ZrO2 particles of 30-40 nm. The maximum specific surface area of them can reach to 384.780 m2/g and there are presences of the inhomogeneous mesopores. Moreover, the template can be removed and tetragonal phase ZrO2 can be obtained without using calcinations, which greatly simplifies the experimental procedure. We also studied the adsorption capability of cage-like ZrO2 and hollow ZrO2 microspheres to methyl orange, the highest adsorption percent was up to 99.5%. The adsorption isotherm conforms to Freundlich equation.

Asunto(s)

Microesferas , Levaduras/metabolismo , Circonio/química , Adsorción , Compuestos Azo/química , Microscopía Electrónica de Rastreo , Difracción de Polvo

RESUMEN

Spinous hollow and core-shell microspheres constructed from ZrO2 nanoparticles and keeping the complex morphology of pollens were prepared by bio-template route. Compared with other bio-templates synthesis, the superiority of our synthesis is that the growth of nanoparticles can be controlled in particular space of template. The theory of pollen as a reactor and a possible formation mechanism were proposed which could explain the tunable structure: under a mild condition, the pollen wall will be controlled as a nanoparticles bio-reactor to form the hollow structure; when under a strenuous condition, pollen wall and pollen interior will act as a whole bio-reactor, and the core-shell structure could be obtained. At the same time, the shell thickness can be controlled through etching pollen wall by different concentrations HCl. These microspheres can be used as photocatalyst due to their unique structure. This work provides a novel pathway to the synthesis of hollow nanostructure spheres with complicated structure and morphology.