Ultra-small UiO-66-NH_(2)nanoparticles immobilized on g-C_(3)N_(4)nanosheets for enhanced catalytic activity

UiO-66-NH_(2),an important metal-organic framework,is usually synthesized by solvothermal method and the particle size is generally larger than 200 nm,which limits its catalytic applications in chemical reactions.It is very meaningful to produce UiO-66-NH_(2) nanoparticles with ultrasmall size,but remains challenging.Herein,we synthesized UiO-66-NH_(2) nanoparticles in size of 8-15 nm that are immobilized on g-C_(3)N_(4)nanosheets.Compared with the UiO-66-NH_(2) synthesized by the traditional solvothermal method(>200 nm),the ultra-small UiO-66-NH_(2) nanoparticles immobilized on g-C_(3)N_(4)have more unsaturated coordination positions and increased Lewis acidity.Owing to these combined advantages,the ultra-small UiO-66-NH_(2)nanoparticles exhibit greatly improved catalytic activity for Meerwein-Ponndorf-Verley reaction than larger UiO-66-NH_(2)particles.

Atomic Bridging of Sn Single Atom with Nitrogen and Oxygen Atoms for the Selective Electrocatalytic Reduction of CO_(2)

The atomic coordination structure of single atom catalysts is crucial in modulating the electrocatalytic reduction of CO_(2)into desirable products.However,there remains limited insight into their roles and catalytic mechanisms.In comparison with commonly proposed metal-N4 moieties,herein the atomic bridging structure of nitrogen-tin-oxygen confined in porous carbon fibers is first presented for the selective reduction of CO_(2).With the detailed identification of such a unique structure,the in situ experimental results and theoretical calculations demonstrate that the bridging structure with reactive oxygen species enables the favorable surface electronic status to form adsorbed intermediate,*COOH for selective CO generation.Typically,the electrocatalyst displays high Faradaic efficiency in reducing CO_(2)into CO,but formate is produced on traditional Sn-based catalysts.Additionally,the solar-driven CO_(2)-H_(2)O system displays a desirable solar-to-CO conversion efficiency of 12.9%.This work provides fundamental guidance for the rational regulation of the atomic coordination structure to improve the production selectivity.

Ionic liquids produce heteroatom-doped Pt/TiO2 nanocrystals for efficient photocatalytic hydrogen production

It is of great importance to develop facile strategies to synthesize catalysts with desirable compositions and structures for high-performance photocatalytic hydrogen generation. In this work, we put forward an ionic liquid assisted one-pot route for the synthesis of heteroatom-doped Pt/TiO2 composite material. This route is simple, environmentally benign and adjustable owing to the designable properties of ionic liquids. The as-synthesized Pt/TiO2 nanocrystals exhibit high activity and stability for the photocatalytic hydrogen generation under simulated solar irradiation. This method can be easily applied to the synthesis of various kinds of metal/TiO2 composites doped with desirable heteroatoms (e.g., F, Cl, Br, etc).

Supercritical CO2 produces the visible-light-responsive TiO2/COF heterojunction with enhanced electron-hole separation for highperformance hydrogen evolution

To construct the heterojunctions of TiO2 with other compounds is of great importance for overcoming its inherent shortages and improving the visible-light photocatalytic performance.Here we propose the construction of TiO2/covalent organic framework(COF)heterojunction with tight connection by a supercritical CO2(SC CO2)method,which helps bridging the transformation paths for photo-induced charge between T i02 and COF.The produced T i02/COF heterojunction performs a H2 evolution of 3,962 nmol·g^-1·h^-1 under visible-light irradiation,which is-25 times higher than that of pure TiO2 and 4.5 folds higher than that of TiO2/COF synthesized by the conventional solvothermal method.This study opens up new possibilities for constructing heterojunctions for solar energy utilization.

Multi-shelled CuO microboxes for carbon dioxide reduction to ethylene

The electroreduction of CO2 to valuable chemicals and fuels offers an effective mean for energy storage.Although CO2 has been efficiently converted into C1 products(e.g.,carbon monoxide,formic acid,methane and methanol),its convention into high value-added multicarbon hydrocarbons with high selectivity and activity still remains challenging.Here we demonstrate the formation of multi-shelled CuO microboxes for the efficient and selective electrocatalytic CO2 reduction to C2H4.Such a structure favors the accessibility of catalytically active sites,improves adsorption of reaction intermediate(CO),inhibits the diffusion of produced OH−and promotes C-C coupling reaction.Owing to these unique advantages,the multi-shelled CuO microboxes can effectively convert CO2 into C2H4 with a maximum faradaic efficiency of 51.3%in 0.1 M K2SO4.This work provides an effective way to improve CO2 reduction efficiency via constructing micro-and nanostructures of electrocatalysts.

Nitrogen-carbon layer coated nickel nanoparticles for efficient electrocatalytic reduction of carbon dioxide

The application of nickel in electrocatalytic reduction of CO2 has been largely restricted by side reaction (hydrogen evolution reaction) and catalyst poisoning.Here we report a new strategy to improve the electrocatalytic performance of nickel for CO2 reduction by employing a nitrogen-carbon layer for nickel nanoparticles.Such a nickel electrocatalyst exhibits high Faradaic efficiency 97.5% at relatively low potential of-0.61 V for the conversion of CO2 to CO.Density functional theory calculation reveals that it is thermodynamically accomplishable for the reduction product CO to be removed from the catalyst surface,thus avoiding catalyst poisoning.Also,the catalyst renders hydrogen evolution reaction to be suppressed and hence reasonably improves catalytic performance.

Several Enantiopure Chiral Building Blocks Derived from D-Mannose and a Formal Synthesis of Dubiusamine C

从 D 甘露糖导出的几块多功能的 chiral 积木被开发，它可以作为 1-hydroxy-3-methyl 的来源发现多样的实用程序在许多自然产品的 enantioselective 合成的结构的单位。自然 dubiusamine-C 的正式合成也被介绍。