Demonstration of joule-level chirped pulse amplification based on tiled Ti:sapphire amplifier

A novel tiled Ti:sapphire(Ti:S)amplifier was experimentally demonstrated with>1 J amplified chirped pulse output.Two Ti:S crystals having dimensions of 14 mm×14 mm×25 mm were tiled as the gain medium in a four-pass amplifier.Maximum output energy of 1.18 J was obtained with 2.75 J pump energy.The energy conversion efficiency of the tiled Ti:S amplifier was comparable with a single Ti:S amplifier.The laser pulse having the maximum peak power of 28 TW was obtained after the compressor.Moreover,the influence of the beam gap on the far field was discussed.This novel tiled Ti:S amplifier technique can provide a potential way for 100 PW or EW lasers in the future.     

Salen–Mg-doped NH2–MIL-101(Cr) for effective CO2 adsorption under ambient conditions

A novel metal-doped metal–organic framework (MOF) was developed by incorporating salen–Mg into NH₂–MIL-101(Cr) structure under ambient conditions. The Schiff base complex was successfully prepared by condensing salicylaldehyde with a free amino group and then coordinating metal ions. Such a structure can endow the sample with higher CO₂ adsorption performance. At 0°C and 1 bar, the salen–Mg-modified sample achieves the maximum adsorption capacity of 2.18 mmol g⁻¹ for CO₂, which was 5.8% higher than the pristine salen–MOF under the same conditions. Notably, the Freundlich model indicates that the CO₂ adsorption process of all samples conforms to reversible adsorption. However, the correlation coefficients (R²) of the Mg-doped sample are lower than that of the pristine sample. Besides, the CO₂/N₂ adsorption selectivity and isosteric heat also show a similar trend. These results indicate that the salen–Mg can enhance the interaction between the material and CO₂ molecules.     

Improved Interfacial Bonding Strength and Reliability of Functionalized Graphene Oxide for Cement Reinforcement Applications

Poor bonding strength between nanomaterials and cement composites inevitably lead to the failure of reinforcement. Herein, a novel functionalization method for the fabrication of functionalized graphene oxide (FGO), which is capable of forming highly reliable covalent bonds with cement hydration products, and therefore, suitable for use as an efficient reinforcing agent for cement composites, is discussed. The bonding strength between cement and aggregates was improved more than 21 times with the reinforcement of FGO. The fabricated FGO also demonstrated many important features, including high reliability in cement pastes, good dispersibility, and efficient structural refinement of cement hydration products. With the incorporation of FGO, cement mortar samples demonstrated up to 40 % increased early and ultimate strength. Such results make the fast demolding and manufacture of light constructions become highly possible, and show strong advantages on improving productivity, saving cost, and reducing CO₂ emissions in practical applications.     

Co-hydrolysis and Seed-Induced Synthesis of Basic Mesoporous ZSM-5 Zeolites with Enhanced Catalytic Performance

For zeolite catalysts, the regulation of active site and pore structure plays an important role in the enhancement of their catalytic performance. In this work, a one-pot and organic template-free co-regulation route is proposed to straightforwardly synthesize basic mesoporous ZSM-5 zeolites with adjustable alkaline-earth metal species. The synthesis pathway combines two decisive strategies: 1) the seed-induced interface assembly growth method and 2) the acidic co-hydrolysis/condensation of aluminosilicate species and alkaline-earth metal (e.g., Mg, Ca, Sr, or Ba) sources. It is interesting that the mesoporous structure was self-evolved through particle-attached seed-interfacial crystallization without the assistance of any template. Meanwhile, the incorporation of alkaline-earth metals species is homogeneous and highly dispersed in the solid products during the whole crystallization process, and finally generate the superior basicity. Catalysis tests of the as-synthesized samples displayed their novel performance in the typical base reaction of Knoevenagel condensation, even for bulky substrates owing to the enhanced diffusion arising from the meso/microporous network. This finding opens new possibilities for facile, cost-effective, and environmentally friendly synthesis of mesoporous high-silica zeolites with tunable acid/base properties, and deepens our understanding of the particle-attached crystallization.     

Catalytic Platinum Nanoparticles Decorated with Subnanometer Molybdenum Clusters for Biomass Processing

The development of improved technologies for biomass processing into transportation fuels and industrial chemicals is hindered due to a lack of efficient catalysts for selective oxygen removal. Here we report that platinum nanoparticles decorated with subnanometer molybdenum clusters can efficiently catalyze hydrodeoxygenation of acetic acid, which serves as a model biomass compound. In contrast with monometallic Mo catalysts that are inactive and monometallic Pt catalysts that have low activities and selectivities, bimetallic Pt–Mo catalysts exhibit synergistic effects with high activities and selectivities. The maximum activity occurs at a Pt to Mo molar ratio of three. Although Mo atoms themselves are catalytically inactive, they serve as preferential binding anchors for oxygen atoms while a catalytic transformation proceeds on neighboring surface Pt atoms. Beyond biomass processing, Pt–Mo nanoparticles are promising catalysts for a wide variety of reactions that require a transformation of molecules with an oxygen atom and, more broadly, in other fields of science and technology that require tuning of surface–oxygen interactions.     

Two Rare-Earth Molecular Ferroelectrics with High Curie Temperatures,Large Spontaneous Polarization,Switchable Second Harmonic Generation Effects,and Strong Photoluminescence

Smart multifunctional molecular ferroelectrics bearing high Curie temperatures and diverse excellent physical properties, such as second harmonic generation (SHG) responses, luminescence, and semiconductivity, among others, have significant applications but have seldom been documented. Herein, the rare-earth metals Nd and Pr are introduced into a simple molecular system (nBu₄N )₃[M(NO₃)_x(SCN)_y] (nBu₄N₌tetrabutyl ammonium, M=rare-earth metal, nBu=CH₃CH₂CH₂CH₂), and two new multifunctional molecular ferroelectrics are obtained: (nBu₄N )₃[Nd(NO₃)₄(SCN)₂] ( 1 ) and (nBu₄N )₃[Pr(NO₃)₄(SCN)₂] ( 2 ). Their distinct heat and dielectric anomaly dependence on temperature verifies that compounds 1 and 2 experience high-temperature para-ferroelectric phase transitions at 408 and 413 K, respectively. Strikingly, both molecular ferroelectrics possess large spontaneous polarization with P_s values of 9.05 and 8.50 μC cm⁻², respectively, and are further characterized by the appearance of multiple intersecting non-180° domains and polarization switching behavior. In particular, compounds 1 and 2 show good stability with only a small decrease in SHG intensity after switching cycles, suggesting that they have great potential for application in nonlinear optical (NLO) switches. Simultaneously, the rare-earth compounds 1 and 2 present bright yellow–red and bright green fluorescence, respectively, at room temperature.     

有机化学实验混合教学模式的设计与实践

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