Xi Zheng

Preparation of hydrophobic hollow silica nanospheres with porous shells and their application in pollutant removal

A series of hydrophobic hollow silica nanospheres with high specific surface areas and porous shells were successfully prepared through combination of a one-step reverse-phase microemulsion route and a simple post selective etching method. These materials owned porous shells and high specific surface areas, which were generated in the etching process. The distribution difference of organic groups among the solid nanosphere was innovatively utilized to create a different etching rate between the surface and the inner part of the solid silica nanosphere. After etching, the organic groups are still present on the surface which together with the rough surface give it hydrophobic properties and the contact angles can reach 150°. The reported materials showed good performance in the removal of 4-NP in water.

Preparation of self-assembled cobalt hydroxide nanoflowers and the catalytic decomposition of cyclohexyl hydroperoxide

α-Co(OH)2 hierarchical nanoflowers were synthesized using a microemulsion as a nanoreactor. These structures were self-assembled from cobalt hydroxide nanoflakes and possessed flowerlike morphology with a diameter of 200–500 nm. These α-Co(OH)2 nanoflowers exhibited high specific area and porosity and show high activity in the decomposition of cyclohexyl hydroperoxide. 99% conversion and 94% selectivity for K–A oil could be obtained.

Cobalt ammonia complex mediated preparation of hollow silica nanospheres with multi-nanochambers

Cobalt-containing SiO2-based nanosphere with multi-nanochambers was prepared via a microemulsion method. Addition of cobalt ammonia complex to microemulsion is a necessary step to obtain this specific structure. This novel material was found to be an efficient catalyst for the decomposition of cyclohexyl hydroperoxide, and high activity of 94% conversion with 93% selectivity for K–A oil could be obtained.

Formation of Strong Basicity on Covalent Triazine Frameworks as Catalysts for the Oxidation of Methylene Compounds

Porous solid bases are increasingly attractive for applications in green chemistry and heterogeneous catalysis under relatively mild conditions. Here, covalent triazine frameworks (CTFs) were first applied as a support for the porous solid strong bases through a redox process between the base precursor KNO3 and CTFs, leading to a relatively low calcination temperature (400 °C). As a result, porous organic frameworks possessing ordered microstructures as well as strong basic sites were successfully synthesized. The materials were characterized by X-ray diffraction, Fourier transform infrared, high-resolution transmission electron microscopy, temperature programmed desorption of CO2, and so forth. The obtained solid bases displayed remarkable catalytic activity in the aerobic oxidation of methylene compounds, and the yield of fluorenones could reach 93.6% at 120 °C, which was nearly 3 times higher than that of the control catalyst. The current research may present a new idea for the construction of porous organic polymers with strong basicity.