Photocatalytic Activity of MoS2 Nanoflower-Modified CaTiO3 Composites for Degradation of RhB under Visible Light.

Nanoflower-like MoS2 deposited on the surface of rectangular CaTiO3(CTO) was designed and synthesized via a simple template-free strategy. Through SEM, TEM, and other characterization methods, the MoS2 nanoflowers were confirmed to be well deposited on the surface of CTO. LED was used as the visible light source, and rhodamine B (RhB) in an aqueous solution was used as the model pollutant to assess the photodegradation activity of the samples. The results showed that the MoS2/CaTiO3(MCTO) composite significantly improved the photocatalytic degradation of rhodamine B (RhB) in water, compared with a single CTO, and with the MCTO-2 composite photocatalysts, 97% degradation of RhB was achieved in 180 min, and its photocatalytic activity was about 5.17 times higher than that of the bare CTO. The main reasons for enhancing photocatalytic performance are the strong interaction between the nanoflower-like MoS2 and rectangular CTO, which can lead to the effective separation of electron transfer and photoexcited electron-hole pairs in MCTO composites. This work provides a new notion for researching an effective method of recycling catalytic materials.

Effect of Cu loading content on the catalytic performance of Cu-USY catalysts for selective catalytic reduction of NO with NH3.

Series of Cu-USY zeolite catalyst with different Cu loading content were synthesized through simple impregnation method. The obtained catalysts were subjected to selective catalytic reduction of NOx with NH3 (NH3-SCR) performance evaluation, structural/chemical characterizations such as X-ray diffraction (XRD), N2 adsorption/desorption, H2 temperature-programmed reduction (H2-TPR), NH3 temperature-programmed desorption (NH3-TPD) as well as detailed in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments including CO adsorption, NH3 adsorption and NO+O2 in situ reactions. Results show that Cu-USY with proper Cu loading (in this work 5Cu-USY with 5 wt.% Cu) could be promising candidates with highly efficient NH3-SCR catalytic performance, relatively low byproduct formation and excellent hydrothermal stability, although its SO2 poisoning tolerability needs alleviation. Further characterizations reveal that such catalytic advantages can be attributed to both active cu species and surface acid centers evolution modulated by Cu loading. On one hand, Cu species in the super cages of zeolites increases with higher Cu content and being more conducive for NH3-SCR reactivity. On the other hand, higher Cu loading leads to depletion of Brønsted acid centers and simultaneous formation of abundant Lewis acid centers, which facilitates NH4NO3 reduction via NH3 adsorbed on Lewis acid centers, thus improving SCR reactivity. However, Cu over-introduction leads to formation of surface highly dispersed CuOx, causing unfavorable NH3 oxidation and inferior N2 selectivity.

Sodium iodide-mediated synthesis of vinyl sulfides and vinyl sulfones with solvent-controlled chemical selectivity.

Vinyl sulfides and vinyl sulfones are ubiquitous structures in organic chemistry because of their presence in natural and biologically active compounds and are very frequently encountered structural motifs in organic synthesis. Herein we report an efficient synthesis of vinyl sulfides and vinyl sulfones via transition metal-free sodium iodide-mediated sulfenylation of alcohols and sulfinic acids with solvent-controlled selectivity.

Au-Catalyzed intermolecular (3 + 2 + 1) and (5 + 2) cycloaddition for the synthesis of 1,4-dioxenes and 4,7-dihydrooxepines.

1,4-Dioxenes and 4,7-dihydrooxepines present interesting potential as motifs for the incorporation of biologically relevant molecules, agrochemicals and materials. In this study, two efficient intermolecular (3 + 2 + 1) and (5 + 2) cycloadditions for the synthesis of 1,4-dioxenes and 4,7-dihydrooxepines are achieved with gold catalysis.

A general ligand design for gold catalysis allowing ligand-directed anti-nucleophilic attack of alkynes.

Most homogenous gold catalyses demand ≥ 0.5 mol% catalyst loading. Owing to the high cost of gold, these reactions are unlikely to be applicable in medium- or large-scale applications. Here we disclose a novel ligand design based on the privileged (1,1'-biphenyl)-2-ylphosphine framework that offers a potentially general approach to dramatically lowering catalyst loading. In this design, an amide group at the 3'-position of the ligand framework directs and promotes nucleophilic attack at the ligand gold complex-activated alkyne, which is unprecedented in homogenous gold catalysis considering the spatial challenge of using ligand to reach anti-approaching nucleophile in a linear P-Au-alkyne centroid structure. With such a ligand, the gold(I) complex becomes highly efficient in catalysing acid addition to alkynes, with a turnover number up to 99,000. Density functional theory calculations support the role of the amide moiety in directing the attack of carboxylic acid via hydrogen bonding.