Synthesis Of Porous Microspheres Research Articles

Boosting the Electrochemical Performance of V2 O3 by Anchoring on Carbon Nanotube Microspheres with Macrovoids for Ultrafast and Long-Life Aqueous Zinc-Ion Batteries.

Zinc-ion batteries (ZIBs) are next-generation energy storage systems with high safety and environmental friendliness because they can be operated in aqueous systems. However, the search for electrode materials with ideal nanostructures and compositions for aqueous ZIBs is in progress. Herein, the synthesis of porous microspheres, consisting of V2 O3 anchored on entangled carbon nanotubes (p-V2 O3 -CNT) and their application as cathode for ZIBs is reported. From various analyses, it is revealed that V2 O3 phase disappears after the initial charge process, and Zn3+ x (OH)2+3 x V2- x O7-3 x ∙2H2 Oand zinc vanadate (Zny VOz ) phases undergo zinc-ion intercalation/deintercalation processes from the second cycle. Additionally, the electrochemical performances of p-V2 O3 -CNT, V2 O3 -CNT (without macrovoids), and porous V2 O3 (without CNTs) microspheres are compared to determine the effects of nanostructures and conductive carbonaceous matrix on the zinc-ion storage performance. p-V2 O3 -CNT exhibits a high reversible capacity of 237mA h g-1 after 5000 cycles at 10 A g-1 . Furthermore, a reversible capacity of 211mA h g-1 is obtained at an extremely high current density of 50 A g-1 . The macrovoids in V2 O3 nanostructure effectively alleviate the volume changes during cycling, and the entangled CNTs with high electrical conductivity assist in achieving fast electrochemical kinetics.

Deposition of aminosilane coatings on porous Al2O3 microspheres by means of dielectric barrier discharges

Advances in the synthesis of porous microspheres and in their functionalization are increasing the interest in applications of alumina. This paper deals with coatings plasma deposited from 3‐aminopropyltriethoxysilane by means of dielectric barrier discharges on alumina porous microspheres, shaped by a vibrational droplet coagulation technique. Aims of the work are the functionalization of the particles with active amino groups, as well as the evaluation of their surface coverage and of the penetration of the coatings into their pores. A multi‐diagnostic approach was used for the chemical/morphological characterization of the particles. It was found that 5 min exposure to plasma discharges promotes the deposition of homogeneous coatings onto the microspheres and within their pores, down to 1 μm.

Radially organized pillars in TiO2 and in TiO2/C microspheres: Synthesis, characterization and photocatalytic tests

► Synthesis of porous microspheres via template processes. ► Two kinds of materials: (1) porous core–shell C/TiO 2 and (2) pure TiO 2 mesoporous microspheres. ► The structure of the TiO 2 phase is constituted by cemented anatase and rutile nanoparticles. ► By changing the temperature of treatment, tunable anatase/rutile composition is obtained. ► Materials exhibit high activity in the photocatalytic oxidation of NO. Porous TiO 2 microspheres with robust texture and high photoactivity were prepared by inflowing a TiO 2 precursor in the confined space of polystyrene-co-divinyl benzene (PS-co-DVB) polymer, working as sacrificial scaffold. The impregnated polymer spheres, upon thermal treatments under N 2 , N 2 /air or pure air flow at temperatures in the 400–500 °C interval, are transformed into porous microspheres. Depending on the gas flow composition, the obtained microspheres are constituted by porous carbon, hybrid core–shell C/TiO 2 or of cemented TiO 2 nanoparticles assembled in elongated pillars. The composition of pure TiO 2 microspheres ranges from pure anatase (400 °C) to the prevailing rutile phase (>475–500 °C). All samples have been extensively characterized by means of SEM/AFM microscopes, N 2 -volumetric porosimetry, XRD and UV–vis analyses. The photodegradation of NO has been used to check the photocatalytic activity of the TiO 2 materials. It is concluded that they exhibit higher photoactivity than the classical benchmark material (Degussa P25). This property together with porous character of the microspheres, the tunable anatase–rutile ratio and the high crystallinity makes these microspheres very interesting materials for applications in photocatalysis. From a physical point of view, the large axial pores and the columnar nature of the spheres can produce the entrapment of the light into the material.

Synthesis of porous microspheres via self-assembly of monodisperse polymer nanospheres

Conventional synthesis of porous spherical particulate polymer resins via suspension polymerisation involves a complex combination of processes (polymerisation, crosslinking, phase separation and microgel formation, microgel fusion and pore in-filling). We have now succeeded in producing porous polymer microspheres via the self-assembly of pre-formed monodisperse poly(styrene-co-methacrylic acid) latex particles (ca. 200 nm). The self-assembly is performed in suspension in toluene and is driven by the removal of water at ca. 105 °C. This thermal process also induces contact fusion of the latex particles.