Titanium-rich TS-1 zeolite for highly efficient oxidative desulfurization

The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions.Herein,we reported an efficient and facile synthesis of nano-sized Ti-rich TS-1(MFI)zeolites by replacing tetrabutyl orthotitanate(TBOT)with tetrabutyl orthotitanate tetramer(TBOT-tetramer)as the titanium source.The introduced TBOT-tetramer slowed down the zeolite crystallization process,and accordingly balanced the rate of incorporating Ti and the crystal growth and inhibited the massive formation of anatase species.Notably,the prepared Ti-rich TS-1 zeolite sample had a Si/Ti as low as 27.6 in contrast to conventional one with a molar ratio of 40.The TBOT-tetramer endowed the titanosilicate zeolites with enriched active titanium species and enlarged external surface area.It also impeded the formation of anatase species,resulting in superior catalytic behavior toward the oxidative desulfurization of dibenzothiophene compared with the conventional TS-1 zeolite counterpart prepared with TBOT.

Robust or nonrobust: On MC-DS-CDMA acquisition in LEO satellite communications

Low Earth Orbit(LEO)satellite communications can provide global coverage in the sixth generation communication(6G)networks.To combat the strong Partial Band Interferences(PBIs)and multipath fading in LEO satellite communication systems,the Multicarrier Direct Sequence Code Division Multiple Access(MC-DS-CDMA)technique is a promising alternative to the traditional Single-carrier Direct Sequence Code Division Multiple Access(SC-DS-CDMA)system for its advantages of high bandwidth efficiency,superior interference rejection capability,and low complexity of parallel signal processing.However,limited studies have been conducted on the performance analysis of MC-DS-CDMA acquisition systems in the presence of a large Doppler shift,a unique characteristic of LEO satellite communications.To bridge this gap,we investigate the performance of MC-DS-CDMA systems with two-dimensional acquisition and noncoherent equal gain combining over Rician fading channel in the presence of the Doppler shift and PBIs.The performance metrics are detection probability and Mean Square Error(MSE)of the Doppler factor and delay.Specifically,we derive the closed-form expressions for the MSE and the Probability Density Function(PDF)of the acquisition decision variable and obtain the detection probability.We conduct extensive numerical experiments to verify the theoretical analysis and performance gain of MC-DSCDMA over the SC-DS-CDMA.The results show that MC-DS-CDMA with two-dimensional acquisition is more robust to multipath Rician fading than SC-DS-CDMA.Moreover,MC-DS-CDMA outperforms SC-DS-CDMA regarding the detection probability and MSE when combating the strong PBIs.

Help from space:grant-free massive access for satellite-based IoT in the 6G era

The Sixth-Generation(6G)standard for wireless communications is expected to realize ubiquitous coverage for massive Internet of Things(IoT)networks by 2030.Satellite-based communications are recognized as a highly promising technical enabler to satisfy IoT service requirements in the 6G era.This study analyzes multiple access technologies,which are essential for the effective deployment of satellite-based IoT.First,we thoroughly investigate the existing research related to massive access,including information-theory considerations as well as Non-Orthogonal Multiple Access(NOMA)and Random Access(RA)technologies.Then,we explore the influence of the satellite transmission environment on multiple access technologies.Based on this study,a Non-orthogonal Massive Grant-Free Access(NoMaGFA)scheme,which reaps the joint benefits of RA and NOMA,is proposed for asynchronous transmissions in satellite-based IoT to achieve improved system throughput and enhance the system robustness under varying traffics.Finally,we identify some important and interesting future developments for satellite-based IoT,including waveform design,transceiver design,resource allocation,and artificial intelligence-enhanced design.

Amino acid-assisted synthesis of TS-1 zeolites containing highly catalytically active TiO_(6)species

Tailoring the Ti coordination states in titanosilicate zeolites to simultaneously improve feedstock conversion and maximize the target product selectivity remains a challenge in the pursuit of high-performance catalysts for selective oxidation reactions.Herein,we provide a facile strategy to synthesize hierarchical anatase-free TS-1(MFI-type)zeolites with tetrahedrally coordinated(TiO_(4))and octahedrally coordinated Ti species(TiO_(6)).The TiO_(4)species provide high epoxide selectivity,while the TiO_(6)species afford improved alkene conversion.This strategy is achieved by synergistically using an L-lysine-assisted approach and a two-step crystallization;the two-step crystallization approach prevents the formation of anatase TiO_(2),while L-lysine stabilizes the TiO_(6)species and ensures efficient incorporation of TiO_(6)into the anatase-free TS-1 zeolites.Compared with their conventional counterparts,which only contain TiO_(4)species,the as-prepared TS-1 zeolites(Si/Ti=36.9)result in a higher 1-hexene conversion(33%),higher TON value(153),and comparable epoxide selectivity(95%).This synthetic strategy provides avenues to tailor the amount and distribution of Ti species in titanosilicate zeolites to achieve high catalytic performances in various processes.

Efficient transesterification over two-dimensional zeolites for sustainable biodiesel production

Basic zeolites have shown great potential as efficient catalysts for biodiesel production in the transesterification reactions.However,conventional three-dimensional(3D)basic zeolites generally suffer from limited base sites and severe mass-transfer restriction,thereby suppressing their catalytic activity.Herein,2D basic zeolites with large external surface areas,hierarchical characteristics,and abundant accessible and stable base sites are prepared by expansion,delamination and subsequent solid-state ion-exchange(SSIE)approach.The facile SSIE method provides more advantages in stabilizing and dispersing high concentration of strong basic sites than the conventional liquid-phase ion-exchange(LIE)approach.Due to the excellent mass transportation and stable basic sites,the 2D Na/ITQ-2 prepared by the SSIE approach shows remarkably enhanced activity and recyclability in the transesterification of triglycerides to produce biodiesel,compared to 3D zeolites and other reported basic zeolites.This work will open the boulevard to the rational design of 2D basic catalysts and expand the potential application of 2D zeolites to biodiesel production and other industrial reactions involving bulky molecules.

Versatile zeolite overlayer on ZnO film enabling high-performance bilayer NO_(2) sensoring

Bilayer structure with functional overlayer has been commonly adopted to resolve the issue of moisture poisoning in chemiresistors.However,the conventional overlayers always suffer from blocking access of gas molecules to sensing layer due to lacking porosity and deteriorated adsorption capability.Herein,taking advantages of the well-defined porous structure and hydrophobic nature of pure silica zeolite,we assembled an overlayer of Pd-PdO clusters-encapsulated mesoporous silicalite-1(MFI)zeolite(named M-S-1)on ZnO sensing layer,to prevent moisture poisoning,and enhance gas diffusion and adsorption capabilities.The inherent capability of MFI zeolite to incorporate monodispersed nanometric(ca.3 nm)Pd-PdO cluster in its void space is of great importance for the NO_(2) adsorption.The Pd-PdO@M-S-1 overlayer can attain negligible moisture interference to the ZnO layer without significantly altering the gas selectivity and baseline resistance,and enhance gas response.Consequently,the Pd-PdO@M-S-1/ZnO bilayer sensor can ultra-selectively(S_(nitrogen dioxide)/S_(interference gas)>4),and ultra-stably detect trace level of NO_(2)(9.5 ppb)at low temperature(370 K)under high levels of humidity(90%RH).This work exemplifies a next-generation solution to design bilayer sensors using zeolite overlayer for eliminating the humidity dependence of the gas-sensing properties.

Integrating Zeolite and Layered Double Hydroxide for Highly Selective Catalytic Production ofγ-Valerolactone

The production ofγ-valerolactone(GVL)from biomass derivatives levulinic acid(LA)based on acidbase metallic catalysts offers a sustainable pathway to the synthesis of valuable chemicals and biofuels.However,the development of efficient metallic catalysts with tunable Lewis acid–base and Brønsted acid sites remains a challenge.Herein,for the first time,we integrated zeolite and layered double hydroxide(LDH),in a core–shell structure,wherein zeolite and CoFe-LDH provided the Brønsted acidic sites and Lewis acid sites,respectively.Meanwhile,oxygen vacancies(OV_(x))acting as Lewis bases were generated on the surface of LDH via Ga doping.An efficient cascade catalytic reaction from LA to GVL was successfully achieved over the designed Beta@LDH-OVx catalyst,affording a superior conversion of LA(>99.9%)and an impressive selectivity to GVL(89.18%).Importantly,the“memory effect”of LDH endowed the catalyst with excellent regeneration of metal active sites.Density functional theory calculations revealed that the introduced OVx facilitated the adsorption of carbonyl oxygen in LA and boosted the production of GVL through the synergistic effect of acid/base sites in the composite catalyst.This work presents a rational design route for the construction of multifunctional catalysts by coupling zeolites and LDHs for highly selective catalytic conversion of biomass.

La ions-enhanced NH_(3)-SCR performance over Cu-SSZ-13 catalysts

Lanthanum(La)ions are generally recognized to cause a decline of the catalytic performance for Cu-SSZ-13 zeolite in the selective catalytic reduction of NO_(x)with NH_(3)(NH_(3)-SCR).Herein,we demonstrate that the NH_(3)-SCR performance and hydrothermal stability of Cu-La-SSZ-13 zeolites can be enhanced with the incorporation of a small amount of La ions.The incorporation of La ions into SSZ-13 favors more Z_(2)Cu^(2+)ions at six-membered rings(6MRs),which results in higher hydrothermal stability of Cu-La-SSZ-13 than that of Cu-SSZ-13.The NO conversion of Cu-La-SSZ-13 achieves 5%–10%higher than that of Cu-SSZ-13 at the temperature range of 400–550℃ after hydrothermal ageing.While introducing excess amount of La ions in SSZ-13 may cause the formation of inactive CuO_(x),leading to the decrease of catalytic activity and hydrothermal stability.Notably,the low-temperature activity of Cu-SSZ-13 with a low Cu content(≤2 wt.%)can be boosted by the introduction of La ions,which is largely due to the improved redox ability of Cu active sites modified by La ions.Density functional theory(DFT)calculations indicate that La ions prefer to locate at eight-membered rings(8MRs)and thus promoting the formation of more Z_(2)Cu^(2+)ions.Meanwhile,the existence of La ions in SSZ-13 inhibits the dealumination process and the transformation from Z_(2)Cu^(2+)to CuO_(x),resulting in its enhanced hydrothermal stability.The present work sheds a new insight into the regulation of secondary metal cations for promoting high NH_(3)-SCR performance over Cu-SSZ-13 zeolite catalysts.

Confining carbon dots in amino-functionalized mesoporous silica:n→π^(*) interaction triggered deep-red solid-state fluorescence

Deep-red and near-infrared emissive carbon dots(CDs)are highly desired for bioimaging,especially in deep tissue imaging,but they are extremely rare and the known ones usually suffer from low-efficient fluorescence in water and aggregation-induced fluorescence quenching in solid state.In this work,CDs with intriguing solvent-dependent and two-photon fluorescence emissions have been prepared by a facile solvothermal method.Detailed characterizations reveal that there is an n→π*interaction between the carboxyl functional groups on CDs and the electron donor groups in solvent,which leads to the increase of energy density of CDs and the decrease of energy level,resulting in the red shift of luminescence with enhanced electron donating ability of solvent.Inspired by this finding,mesoporous silica nanoparticles(MSNs)with suitable pore size and low biological toxicity are modified by amino groups to confine CDs,thus the deep-red fluorescence emission is achieved both in solid state and in water facilitated by the n→π*interaction of host-guest.The as-prepared CDs@EDA-MSN composite exhibits high-efficient fluorescence with 650 nm wavelength,low toxicity,and good biocompatibility,which endow them a promising application in bio-imaging.

Female scientists in nano research

Female scientists are playing more and more important roles in science-related fields,although they just account for a minority(only 30%)of the scientific community worldwide,according to the 2020 data from the Institute for Statistics of UNESCO.In fact,female researchers have been the mainstay in organizing and guiding the scientific research in many fields.Showing the growing impact of female scientists is of significance as role models to enlighten younger generations and particularly encourage young girls to dedicate in science.The Special Issue of“Female scientists in nano research”publishes such a collection that shares the research outcomes from those labs led by female scientists in nano-related research fields and showcases their high impacts on many aspects of nanomaterials and applications.This special issue collects 58 papers,including 16 reviews and 42 original research articles,which present the latest advances in area across diverse compelling topics in nano-science and technology,such as nanoscience for fluorescence and bioimaging,nanomaterials for energy,electronics and catalysis,sensing platforms based on nanoscience,nanobiotechnology and nanomedicine.

凝聚态化学的研究对象与主要科学问题

本文提出了"凝聚态化学(Condensed Matter Chemistry)"的概念,提出其研究对象是由传统化学上被视为反应主体的原子、离子以及分子等"基本粒子",藉"稳定的粘连关系"凝聚形成的具有特定组成、多层次结构与性质、功能的物质凝聚态。本文以固态为例,讨论了(1)凝聚态的多层次结构;(2)凝聚态的化学性质与化学反应;(3)凝聚态构筑化学中的前沿科学问题;(4)凝聚态化学中的高新表征方法与技术的发展与开拓。并对四个领域中的主要科学问题进行了比较深入的探讨,为进一步再认识传统化学,特别是对其中心问题,即化学反应的再认识提供了方向与基础,为开展"凝聚态的多层次结构-化学性质与化学反应-凝聚态物质的构筑定向合成与精准制备"三个方面的关系研究,总结规律与"分态"建立"凝聚态结构理论"与"凝聚态化学反应理论",建设"凝聚态化学"提供了科学体系与内容,并为进一步开展"凝聚态工程学"研究提供了前提与基础。

Roles of Hydroxyl Groups during Side-Chain Alkylation of Toluene with Methanol over Zeolite Na-Y： A Density Functional Theory Study

The side-chain alkylation of toluene with methanol over alkali-cation-containing zeolite Y is an important reaction for industrial production of styrene,but the exact mechanism of this reaction is still unclear.The most accepted opinion is that the Lewis acid-base sites in zeolite Y activate the transformation from methanol to formaldehyde,the side-chain alkylation of toluene with formaldehyde,and the formation of 2-phenylethanol and styrene afterwards.In this study,we investigate the roles of various types of hydroxyl groups that could possibly exist in zeolite Na-Y during this reaction,including the Br6nsted acid sites and the terminal Al-OH and Si-OH groups,respectively.Through density functional theory （DFT） calculations,we find that the Brtnsted acid sites in Na-Y may catalyze the ring alkylation of toluene and be responsible for the formation of xylene,a side product discovered in experiments.More importantly,we find,for the first time,a new reaction pathway from 2-phenylethanol to styrene over various types of hydroxyl groups in Na-Y,which is kinetically more favorable than the conventional pathway.According to our calculation results,the most possible mechanism for this styrene production process may involve reactions over both the Lewis acid-base sites and the hydroxyl groups in Na-Y.

Carbon Dots-in-Zeolite via In-Situ Solvent-Free Thermal Crystallization:Achieving High-Efficiency and Ultralong Afterglow Dual Emission

Organic afterglow materials are highly desirable for optoelectronic applications,but they usually suffer from complex preparation process,low quantum efficiency,and short lifetime due to the ultrafast deactivation of the highly active excited states involved.Here,we succeeded in achieving solventfree thermal syntheses of high-efficiency afterglow CDs@zeolite composite materials by simply grinding the solid raw materials of zeolite and precursor CDs at room temperature,followed by thermal crystallization.This method afforded maximum embedding of CDs into growing zeolite crystals,as well as strong host–guest interaction to surpass the nonradiative transition of CDs,thus producing composite materials with ultralong dual emission of thermally activated delayed fluorescence and room temperature phosphorescence with a record high lifetime of 1.7 and 2.1 s,respectively,and the quantum yield of 90.7%.Furthermore,in a preliminary experiment,we applied the composite materials in alternatingcurrent light-emitting diode supplementary lighting,which exhibited a promising potential in optoelectronic applications.

Lifetime-Engineered Phosphorescent Carbon Dots-in-Zeolite Composites for Naked-Eye Visible Multiplexing

Lifetime-coded optical multiplexing has attracted wide attention due to avoiding spectral overlap and background interference.At present,most of the materials used for lifetime-coded multiplexing involve rare-earth metal ions with their lifetime domains in the microsecond range,thus greatly limiting their application scope.

Layer-by-Layer Approach to Superhydrophobic Zeolite Antireflective Coatings

Antireflection surfaces and coatings have attracted considerable interests because they can maximize light transmittance of the substrates. In this work, zeolite antireflective （ZAR） coatings are prepared via layer-by-layer （LBL） assembly of MFI-type zeolite silicalite-1 and polyelectrolyte. A micro- and macroporous hierarchical structure was obtained which contributes to the antireflective property of the zeolite coatings. The light transmittance of the coating on quartz can achieve as high as 99.3% at 650 nm. Furthermore, a superh~/drophobic ZAR coating can be obtained by chemical modification with 1H,1H,2H,2H-perfluorooctyl-triethoxysilane. This work demonstrates that zeolites are excellent candidates as high transparent superhydrophobic coatings.

Luminescence anti-counterfeiting:From elementary to advanced

Luminescence anti-counterfeiting derives from the easily changeable luminescence behaviors of luminescence materials under the regulation of various external stimuli(such as excitation light,chemical reagent,heat,and mechanical force,etc.)and luminescence lifetime,which plays an important role in preventing forgery of currency,artworks,and product brands.According to the numbers of changes of anti-counterfeiting labels under various regulation conditions,luminescence anti-counterfeiting can be classified into three levels from elementary to advanced:single-level anti-counterfeiting,double-level anti-counterfeiting,and multilevel anti-counterfeiting.In this review,the recent achievements in luminescence anti-counterfeiting are summarized,and the regulation of various factors to anti-counterfeiting labels is discussed.Finally,existing problems,future challenges,and possible development directions are proposed in order to realize facile,quick,low-cost,environmentally friendly,and difficult-to-replicate advanced luminescence anti-counterfeiting.

One-Pot Three-Dimensional Printing Robust Self-Supporting MnO_(x)/Cu-SSZ-13 Zeolite Monolithic Catalysts for NH_(3)-SCR

Honeycomb cordierite coated with Cu-SSZ-13 zeolite is widely used for the selective catalytic reduction of NO_(x) with NH_(3)(NH_(3)-SCR)to reduce pollutants from vehicle emissions.However,conventional honeycomb catalysts fabricated via coating techniques are limited by low zeolite loadings,loss of the deposited zeolites,and complicated preparation processes.Herein,a facile,one-step three-dimensional(3D)printing strategy is developed to construct MnO_(x)/Cu-SSZ-13 monolithic catalysts with excellent catalytic performance for NH_(3)-SCR.Iron-containing halloysite nanotubes(Fe-HNTs)are introduced as printing ink additives to ensure mechanical stability and modulate the NH_(3)-SCR performance of monolithic catalysts in high temperature conditions.In situ incorporation of Mn into the Cu-SSZ-13 zeolite monoliths during the 3D printing process boosts the mechanical strength of the monolithic structures from 2.54 MPa to 4.33 MPa as well as broadens the temperature window(165-550℃)of the catalysts for NH_(3)-SCR with NO_(x) conversion of above 80%.Such robust multicomponent-integrated 3D-printed selfsupporting catalysts not only possess high zeolite loading and excellent catalytic activity,but also avoid complicated manufacturing processes,which contrasts with conventional honeycomb catalysts fabricated by extrusion coupled with coating.

Porous Membranes with Special Wettabilities:Designed Fabrication and Emerging Application

Porous materials have become a burgeoning research interest in materials science because of their intrinsic porous characteristics,versatile chemical compositions,and abundant functionalities.Recently,inspired by natural superwetting surfaces originating from the cooperation of surface energy and surface geometry,porous membranes with special wettabilities are finding emerging opportunities associated with a wide variety of environmental and energy-related applications.This review will present an overview of the state-of-the-art research on the designed fabrications and applications of superwetting porous membranes based on zeolites,metal–organic frameworks(MOFs),porous organic materials(POMs),and mesoporous materials.General synthetic strategies for the fabrication of porous membranes(e.g.,hydrothermal/solvothermal crystallization,interfacial polymerization,electrospinning,etc.),and principles for tuning the wettability of porous membranes through surface energy modulation are introduced.Furthermore,their emerging applications as oil–water separation membranes,lithium-ionbattery separators,self-cleaning layers,and anticorrosion coatings are demonstrated.Finally,we emphasize on future perspectives regarding the development of superwetting porous membranes for practical applications.

Systematic Study of Ti-Distribution in Titanosilicate *BEA Zeolites via Symmetry-Adapted Enumeration

The high performance of titanosilicate zeolites in various industrial oxidation reactions is highly affected by the distribution of Ti atoms in their frameworks. Because of their structural complexity, previous theoretical studies mainly focus on the preferential location of single Ti atoms within the unit cells of titanosilicate zeolites. When multiple Ti atoms are required, conventional approaches consider only symmetrically related T sites to reduce the computation complexity. Such symmetry-constrained approaches obviously overlooked many possible configurations. Herein, we conduct a systematic study on the distribution of two Ti atoms in the unit cell of titanosilicate zeolite *BEA. Different from conventional symmetry-constrained approaches, we introduce two Ti atoms simultaneously without any constraint and adopt a symmetry-adapted algorithm to enumerate all possible configurations for double-Ti introduction. We generate a total of 273 distinct configurations and analyze the Ti-distribution via Boltzmann statistics. We find that many of the configurations overlooked by conventional symmetry-constrained approaches indeed exhibit more feasible energies, which may lead to different Ti-distributions. Our study indicates the necessity of unconstrained introduction of Ti atoms when multiple-Ti atoms are considered for calculations.

Intrinsic chiral photoswitches manipulate soft-materials

Nature Photonics 16,226–234(2022)https://doi.org/10.1038/s41566-022-00957-5 Advanced Materials 34,2110170(2022)https://doi.org/10.1002/adma.202110170 Due to the lack of appropriate reversible photoswitches,efficiently remote photoprogramming of self-organized soft helical superstructures represents a formidable challenge in particularly allowing multiple stable states,tuning over a broad spectral range and establishing coupling balance between photonic resonance and transmission.The team of Weihong Zhu,Zhigang Zheng and Ben Feringa brings forth a series of exciting light-switchable intrinsic chiral diarylethenes with extremely large helical twisting power(HTP)to enable the dynamic,helical,and optical microstructure manipulation of liquid crystals(LCs),unprecedentedly achieving controllable,selectable,and extractable multi-stable reflection states,meanwhile avoiding the inherent orientation disorderliness of LCs caused by multiple chiral sources.A cutting-edge multiple anticounterfeiting technique,featuring color-tunability,erasability,reversibility,multi-stability and viewing-angle dependency of pre-recorded patterns,has been well demonstrated with the overwhelming intrinsic chiral superstructures.The new exciting strategy can create a gorgeous landscape of optical information processing and configuring,and even build up a unique laser in quadridimensional manipulation of wavelength,wavefront,spin angular momentum,and orbital angular momentum,endowing a sharp and narrow band-width with both remarkable thermodynamic stability and robust fatigueresistance.