Visible-Light-Driven Selective Photocatalytic Hydrogenation of Cinnamaldehyde over Au/SiC Catalysts.

Highly selective hydrogenation of cinnamaldehyde to cinnamyl alcohol with 2-propanol was achieved using SiC-supported Au nanoparticles as photocatalyst. The hydrogenation reached a turnover frequency as high as 487 h(-1) with 100% selectivity for the production of alcohol under visible light irradiation at 20 °C. This high performance is attributed to a synergistic effect of localized surface plasmon resonance of Au NPs and charge transfer across the SiC/Au interface. The charged metal surface facilitates the oxidation of 2-propanol to form acetone, while the electron and steric effects at the interface favor the preferred end-adsorption of α,ß-unsaturated aldehydes for their selective conversion to unsaturated alcohols. We show that this Au/SiC photocatalyst is capable of hydrogenating a large variety of α,ß-unsaturated aldehydes to their corresponding unsaturated alcohols with high conversion and selectivity.

Synthesis and application of a microgel-supported acylating reagent by coupled ring-opening metathesis polymerization and activators re-generated by electron transfer for atom transfer radical polymerization.

A novel microgel-supported acylating reagent (MGAR) was prepared by combining ring-opening metathesis polymerization (ROMP) and Activators Re-Generated by Electron Transfer for Atom Transfer Radical Polymerization (ARGET ATRP): (1) synthesis of an ATRP macroinitiator 3 by living ROMP of oxanorbornene-based activated ester 1, derived from N-hydroxysuccinimide, using the Grubbs initiator RuCl(2)(PCy(3))(2)(=CHPh) and (Z)-but-2-ene-1,4-diyl bis(2-bromopropanoate) (BDBP) as a terminating agent; (2) synthesis of MGAR 4 by ARGET ATRP of styrene (S) and divinylbenzene (DVB) using the prepared macroinitiator 3, a CuCl(2)/Me(6)TREN (tris[2-(dimethylamino)ethyl]amine) catalyst system, a Sn(Oct)(2) [tin(II)2-ethylhexanoate] reducing agent. The synthesized microgels 4 exhibit excellent acyl (acetyl, benzoyl, phenylsulfonyl) transfer properties for primary and secondary amines (n-BuNH(2), Et(2)NH, morpholine, etc.) under mild conditions (25 degrees C, 13.5-14 h) affording N-acylamines with high yield (95.6-100%) and purity (94.1-96.0%).

Controlled synthesis of polylactides using biogenic creatinine carboxylate initiators.

Two biogenetic guanidine carboxylates, i.e., creatinine acetate (CRA) and creatinine glycolate (CRG) based on creatinine (CR) were synthesized and structurally characterized by (1)H NMR, (13)C NMR and X-ray diffraction (XRD) analysis of the single crystals. The characterization demonstrated that CRA and CRG are CR-guanidinium carboxylates in nature, and the carboxylates are associated with the guanidinium via hydrogen bonds. CRA and CRG were successfully used as single-component initiators for ring-opening polymerizations (ROPs) of l-lactide (LLA), dl-lactide (DLLA) producing polymers with controlled molecular weights and narrow polydispersities (PDI = 1.16-1.26). The investigation on the kinetics of the ROPs indicated the typical characteristics of living polymerization as evidenced by the linear relationship of ln [M](0)/[M](t) versus time and M(n) (number-average molecular weight of formed polymer) versus monomer conversion. A study of the terminator-adding effect on the growing polymers revealed that the polymerization follows the coordination propagation mode. The structures of the living oligomers and product polymers were characterized with (1)H NMR spectroscopy. The mechanism of the polymerization was proposed on the basis of the experimental investigation.

Particle size-control enables extraordinary activity of ruthenium nanoparticles/multiwalled carbon nanotube catalysts towards the oxygen reduction reaction.

Catalysts with high efficiency for the oxygen reduction reaction (ORR) play a vital important role in fuel cells and metal-air batteries. Herein, Ru nanoparticles are highly dispersed on functional multi-walled carbon nanotubes (MWCNTs) by a facile impregnation-reduction method. The particle sizes of Ru nanoparticles are simply and effectively adjusted by the concentration of the Ru precursor. Benefiting from the optimal Ru particle size (2.1 nm), a large electrochemically active surface area and fast electron transport, the Ru/MWCNT catalyst shows outstanding ORR activity and durability via a four-electron pathway, producing a diffusion-limited current density of 4.7 mA cm-2 with a half-wave potential of 0.72 V (vs. RHE). Such performance is better than that of a commercial 10 wt% Pt/C catalyst. Density functional theory calculation results reveal that the Oads adsorption on the surface of Ru increases gradually with the addition of the RuOx layer. The Ru/MWCNT catalyst with a particle size of 2.1 nm features appropriate Oads adsorption energy due to the formation of an optimal RuOx/Ru interface for the facilitation of the ORR.

One-step synthesis of Ag/AgCl/GO composite: A photocatalyst of extraordinary photoactivity and stability.

Recently, the photocatalytic applications of silver chloride have been paid closed attention for the excellent ability to photodegrade organic pollutants. Comparing with other catalysts, the silver chloride presents outstanding photocatalytic activity. However, it also suffers from the poor photocatalytic stability. This very paper is focusing on the one-step wet chemical process of preparing Ag/AgCl/GO photocatalyst with high photocatalytic activity and stability. The detailed characterizations were particularly carried out in order to investigate the photo-catalytic activity and stability. Meanwhile the morphology, chemical composition as well as crystalline structure were investigated. It is found that the as-prepared Ag/AgCl/GO composite exhibited an ultrahigh photocatalytic activity and stability in the process of photodegrading RhB. The unique catalytic activity has been discussed based on the SPR effect in Ag nanoparticles on AgCl surface and the separation of photo-generated electron-hole pairs, the primary benefit of the stability owes a great deal to GO which can capture the photo-generated electrons in case they reduce Ag+ ion or recombine the excited holes.