Crystal-phase engineering of PdCu nanoalloys facilitates selective hydrodeoxygenation at room temperature.

Selective hydrodeoxygenation of biomass-derived aromatic alcohols to value-added chemical or fuel is of great importance for sustainable biomass upgrading, and hydrodeoxygenation of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) is one of the most attractive reactions. Achieving the conversion of HMF to DMF using H2 at ambient temperature is challenging. In this work, we used PdCu nanoalloys to catalyze the selective hydrodeoxygenation reaction of HMF to DMF using H2 as the reducing agent. The reaction path and the product selectivity are governed by the crystallographic phase of the PdCu nanoalloys. It was discovered that body-centered cubic (BCC) PdCu nanoalloys supported on activated carbon (AC) exhibited outstanding performance with 93.6% yield of DMF at room temperature (PdCu/AC-BCC). A combination of experimental and density functional theory (DFT) studies showed that the tilted adsorption modes of furanic intermediates on PdCu-BCC nanoalloy surfaces accounted for the high selectivity of DMF; however, furan ring was activated on PdCu face-centered cubic (FCC) nanoalloy surfaces. Furthermore, PdCu/AC-BCC could also catalyze the hydrodeoxygenation of other aromatic alcohols at room temperature while maintaining the aromatic structures. This work opens the way for selective hydrodeoxygenation of the aromatic alcohols at room temperature with the aromatic ring intact.

A fully heterogeneous catalyst Br-LDH for the cycloaddition reactions of CO2 with epoxides.

Herein, we developed a fully heterogeneous catalyst (Br-LDH), where the bromide and the hydroxyl are combined in layered double hydroxides (LDH) and cooperate very well in promoting the cycloaddition of CO2 with epoxides. The selectivity and yield of propylene carbonate could reach 95.5% and 92.0%, respectively.

A new route to synthesize aryl acetates from carbonylation of aryl methyl ethers.

Ether bond activation is very interesting because the synthesis of many valuable compounds involves conversion of ethers. Moreover, C-O bond cleavage is also very important for the transformation of biomass, especially lignin, which abundantly contains ether bonds. Developing efficient methods to activate aromatic ether bonds has attracted much attention. However, this is a challenge because of the inertness of aryl ether bonds. We proposed a new route to activate aryl methyl ether bonds and synthesize aryl acetates by carbonylation of aryl methyl ethers. The reaction could proceed over RhCl3 in the presence of LiI and LiBF4, and moderate to high yields of aryl acetates could be obtained from transformation of various aryl methyl ethers with different substituents. It was found that LiBF4 could assist LiI to cleave aryl methyl ether bonds effectively. The reaction mechanism was proposed by a combination of experimental and theoretical studies.

Catalysis of photooxidation reactions through transformation between Cu2+ and Cu+ in TiO2-Cu-MOF composites.

Novel porous TiO2@Cu3(BTC)2 composites, which were synthesized using ionic liquids (ILs) as solvents, exhibited excellent activity for photooxidation of styrene to 4-aryl tetralones and promoting the Glaser coupling reaction with O2 under light irradiation. It was discovered that the transformation between Cu2+ and Cu+ was crucial for enhancing the photocatalytic performance.

Selective hydrogenation of unsaturated aldehydes over Pt nanoparticles promoted by the cooperation of steric and electronic effects.

The selective hydrogenation of α,ß-unsaturated aldehydes to unsaturated alcohols can reach high selectivity and activity at room temperature using Pt nanoparticles immobilized on a non-porous Al2O3 support stabilized by aspartic acid. Aspartic acid molecules had a significant steric effect on C[double bond, length as m-dash]C hydrogenation and could modify the electronic state of metal particles.

Synthesis of nitrogen and sulfur co-doped hierarchical porous carbons and metal-free oxidative coupling of silanes with alcohols.

Hierarchically porous N and S co-doped carbon was prepared by using 2,5-dihydroxy-1,4-benzoquinone as the carbon source, thiourea as the N and S source, and SiO2 particles as the template. Using the material as the catalyst, oxidative coupling of silanes with alcohols was conducted for the first time under metal-free conditions.

Supercritical Fluid-Driven Polymer Phase Separation for Microlens with Tunable Dimension and Curvature.

Microlenses are highly sought as reliable means for high-resolution optical imaging at low illumination intensities. Plano-convex configuration with tunable dimension and curvature is an essential feature in the microlens fabrication. In this study, we present a facile and green route for preparing well-defined microlenses based on polymer phase separation in the presence of supercritical carbon dioxide (scCO2). The behaviors of linear polymethylmethacrylate protruded from cross-linked silicone network in scCO2 environment are investigated from the perspectives of thermodynamics and kinetics. Microlenses with dimensions from 2 to 15 µm and contact angles from 55° to 112° are successfully obtained through the adjustment of the kinetic conditions and outgassing rate. With the tunable focal length, they exhibit intrinsic function of discerning submicroscale patterns that are unable to be observed directly under optical microscope. Moreover, size confinement on the substrate results in the generation of well-ordered microlens arrays, affording great promise for applications in bioimaging, photolithography, light harvesting, and optical nanosensing.

High-Internal-Phase Emulsion Tailoring Polymer Amphiphilicity towards an Efficient NIR-Sensitive Bacteria Filter.

Emulsions having a high internal-phase volume fraction­termed as HIPEs for high internal phase emulsions­are in high demand as templates for functional macroporous materials. Designing molecular surfactants with appropriate amphiphilicity plays a critical role in the HIPE preparation. In this study, successful tailoring of the amphiphilicity of the originally hydrophobic block co-polymer of polystyrene-b-polyvinylpyridine (PS-b-P4VP) is reported. In combination with trifluoroacetic acid, less than 5 wt% of the polymer-CF3COOH system is feasible as a surfactant for HIPE preparation; this is lower than the amounts typically needed for commonly used commercial surfactants. Using the HIPEs as templates, well-defined closed- and open-cell macroporous triacrylate-based monoliths are fabricated simply through the adjustment of the ratio of the water phase to oil phase. After coating the resulting macroporous material with polypyrrole nanoparticles, the system can be exploited as an NIR-sensitive filter for bacteria; it not only excludes oversized bacteria, but it also kills the bacteria with the help of NIR-induced heat.