Search

a series of different substituents-modified C 2 v -symmetric cobaltoporphyrin complexes have been designed, synthesized and applied as efficient catalysts in conjunction with tetrabutylammonium iodide (TBAI) for the cycloaddition of epoxides and carbon dioxide. The porphyrin skeleton architectures with steric and electronic variation would deeply affect their catalytic performance. [5,15-Di(4-methoxyphenyl)porphyrin]cobalt(III) chloride (c-1) is the most effective catalyst under optimal reaction conditions. Foundational kinetic study results catalyzed by catalysts c-1 , c-2 , c-3 and c-4 reveal that the catalytic performance of electron-donating group-modified cobaltoporphyrin is better than it of electron-withdrawing group-modified ones, and high steric hindrance has a minor negative impact to its catalytic performance. [Display omitted] • Efficient C 2 v -symmetric metalloporphyrin catalysts were synthesized for the cycloaddition of epoxides and CO 2. • The catalytic performance is strongly dependent on the porphyrin skeleton with steric and electronic variation. • Detailed kinetic investigations were carried out by four catalysts. [ABSTRACT FROM AUTHOR]

Rationally designing heterostructure is a promising way to promote the charge carrier separation of intrinsic photocatalysts, thus contributes the improvement of solar to chemical energy conversion. Herein, a novel isotype heterojunction consisted of MCN and UCN, respectively derived from hydrothermally-treated melamine and urea, was synthesized. Owing to the well compatibility and matched band structure, an S-scheme charge transfer mechanism is confirmed for working on MCN/UCN isotype heterojunction, thus endowing strong redox ability, efficient charge carrier separation efficiency and prolonged lifetime. As a result, MCN/UCN exhibits improved photocatalytic water splitting activity under visible light irradiation, which displays approximately 5.5 and 1.8-fold enhancement as compared to the pure MCN and UCN, respectively. The rationally synthesized S-scheme isotype heterojunction will pave the way for developing highly efficient g-C 3 N 4 -based photocatalysts. Unlabelled Image • MCN/UCN S-scheme isotype heterojunction were prepared. • MCN/UCN heterojunction displays prolonged charge carrier lifetime. • MCN/UCN heterojunction shows enhanced photocatalytic H 2 evolution rate. • S-scheme mechanism is confirmed for MCN/UCN hybrids in water splitting. [ABSTRACT FROM AUTHOR]

Abstract: Titanium carbide (TiC) was prepared via one simple route by the reaction of metallic magnesium powders with titanium dioxide (TiO2) and potassium acetate (CH3COOK) in an autoclave at 600°C and 8h. Phase structure and morphology were characterized by X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM). The results indicated that the product was cubic TiC, which consisted of particles with an average size of about 100nm in diameter. The product was also studied by the thermogravimetric analysis (TGA) and its photocatalysis. It had good thermal stability and oxidation resistance below 350°C in air. In addition, we discovered that the cubic TiC powders exhibited photocatalytic activity in degradation of Rhodamine-B (RhB) under 500W mercury lamp light irradiation. [Copyright &y& Elsevier]

Abstract: Chain Fe3O4 nanoparticles encapsulated in worm-shaped carbon shell (defined as “WCCIOs”) were in situ synthesized by copyrolysis of polyethylene, malated-polypropylene and ferrocene in the presence of 10 ml H2O in an autoclave at 700 ∘C for 12 h. The shell thicknesses of these WCCIOs are about 180 nm and the lengths reach up to several micrometers. And the average size of the Fe3O4 nanoparticles inside the worm-shaped carbon shell is about 100 nm. The shapes and compositions of WCCIOs were simply controlled by adjusting the reaction temperatures and relative amounts of the precursors. On the basis of the experimental results, the formation process of the WCCIOs is discussed. The WCCIOs possess well acid resistance, which differs from those reported previously: the nanoparticles were embedded inside the thicker carbon shell. It is also found that the coercivity (Hc) value of the WCCIOs is much higher than that of bare Fe3O4 nanoparticles and bulk Fe3O4. [Copyright &y& Elsevier]

Abstract: Two kinds of new morphology of carbon nanomaterials, carbon nanocables and branched-nanobelts can been produced by pyrolyzing ethylene glycol monvethyl ether (CH3CH2OCH2CH2OH) with Fe as catalyst at 650–700°C. The carbon nanocables are made of two parts, the interior carbon nanowires encapsulated in the outer carbon nanotubes. For the nanocables, HRTEM images reveal that the crystallinity of the outer carbon nanotubes is better than that of the interior carbon nanowires. HRTEM image shows that the junctions of the branched-nanobelts are composed of graphitic layers that are almost perpendicular to the respective axis of the branched-nanobelts. The catalysts, temperature and reaction time were investigated. The possible growth mechanism for the as-synthesized carbon structures is discussed. [Copyright &y& Elsevier]