High-temperature-annealed Al N(HTA-Al N) templates provide ideal substrates for high-quality Al Ga N epitaxy. However, the significant compressive stress accumulated within the Al Ga N layer makes it challenging to ac...High-temperature-annealed Al N(HTA-Al N) templates provide ideal substrates for high-quality Al Ga N epitaxy. However, the significant compressive stress accumulated within the Al Ga N layer makes it challenging to achieve a smooth surface free of hexagonal hillocks on these templates. To address this issue, we investigate the mechanism of compressive stress accumulation during the growth of Al Ga N-based epilayers on HTA-Al N templates using in-situ curvature analysis in this study. To verify the mechanism, a low-Al-content Al Ga N interlayer is introduced between the Al N epilayer and the subsequent Al Ga N epilayer. The larger a-plane lattice constant of this interlayer relative to the Al Ga N epilayer slows the accumulation rate of compressive stress. The hexagonal hillock can be effectively suppressed and the surface of Al Ga N epilayer can be significantly regulated by adopting various low-Al-content Al Ga N interlayers. This work provides a comprehension on the stress accumulation mechanism in Al Ga N epilayers and a feasible method to obtain hillock-free surface of Al Ga N epilayers on HTA-Al N templates,which will be beneficial for fabricating Al Ga N based devices.展开更多
Enhancing the catalytic activity of catalysts is a core objective in their design and synthesis processes,and the accessibility of active sites is one of the crucial factors determining catalyst activity.Polyoxometala...Enhancing the catalytic activity of catalysts is a core objective in their design and synthesis processes,and the accessibility of active sites is one of the crucial factors determining catalyst activity.Polyoxometalate-based metal-organic complexes(POMOCs)with well-defined structures,which combine the advantages of POMs and MOCs,may offer the possibility to construct catalysts with highly accessible active sites.In this study,a series of POMOCs were successfully designed and synthesized using different POM templates,including[CoII1.5(L)1.5(PMo12O40)(H_(2)O)4]·3H_(2)O(Co-PMo12),[CoII1.5(L)1.5(PW12O40)(H_(2)O)4]·3H_(2)O(Co-PW12),[CoII2(L)2-(SiW12O40)(H_(2)O)4]·11H_(2)O(Co-SiW12),and H[CoII2.5(L)3-(P2W18O62)(H_(2)O)8]·10H_(2)O(Co-P2W18),which were characterized by Fourier transform infrared spectroscopy,powder X-ray diffraction,and single crystal X-ray diffraction.The differences in catalytic activity among the four POMOCs for olefin epoxidation were attributed to the distinct accessibility of Co(II)sites upon thermal activation.Among them,Co-P2W18 achieved a remarkable 99%yield of 1,2-epoxycyclooctane within 3 h at room temperature using O_(2)as the oxidant,owing to its highly accessible unsaturated Co(II)sites.Co-P2W18 exhibits significantly superior catalytic activity for the cyclooctene epoxidation reaction compared to most reported catalysts.Additionally,the reaction mechanism was investigated using density functional theory.展开更多
Nano hierarchical mesoporous ZSM-5 catalysts were prepared with cationic dimethyldiallyl ammonium chloride acrylamide copolymer（PDDA） as a soft second template. Using ZSM-5 catalyst as a matrix,Zn/ZSM-5 catalysts we...Nano hierarchical mesoporous ZSM-5 catalysts were prepared with cationic dimethyldiallyl ammonium chloride acrylamide copolymer（PDDA） as a soft second template. Using ZSM-5 catalyst as a matrix,Zn/ZSM-5 catalysts were also obtained by the wet impregnation method. The effect of the PDDA amount and Zn loadings on the properties of the catalysts,including crystallinity,morphology,textural properties,acid nature and catalytic activity in MTG reaction,was investigated by XRD,FESEM,TEM,Nitrogen adsorption–desorption isotherms and NH3-TPD method,respectively. The MTG reaction was performed in a fixed bed reactor,and the result revealed that the nano hierarchical ZSM-5 catalyst prepared with a PDDA/Si molar ratio of 0.070 possesses longer stable phase of 70 h with a liquid hydrocarbon selectivity of 29.8%.Zn/ZSM-5 catalyst with a Zn/ZSM-5 ratio of 0.07 wt.% shows the highest liquid hydrocarbon selectivity,reaching 62.5%.展开更多
Transition metal phosphides(TMPs)have been regarded as alternative hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts owing to their comparable activity to those of noble metal-based catalysts...Transition metal phosphides(TMPs)have been regarded as alternative hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts owing to their comparable activity to those of noble metal-based catalysts.TMPs have been produced in various morphologies,including hollow and porous nanostructures,which are features deemed desirable for electrocatalytic materials.Templated synthesis routes are often responsible for such morphologies.This paper reviews the latest advances and existing challenges in the synthesis of TMP-based OER and HER catalysts through templated methods.A comprehensive review of the structure-property-performance of TMP-based HER and OER catalysts prepared using different templates is presented.The discussion proceeds according to application,first by HER and further divided among the types of templates used-from hard templates,sacrificial templates,and soft templates to the emerging dynamic hydrogen bubble template.OER catalysts are then reviewed and grouped according to their morphology.Finally,prospective research directions for the synthesis of hollow and porous TMP-based catalysts,such as improvements on both activity and stability of TMPs,design of environmentally benign templates and processes,and analysis of the reaction mechanism through advanced material characterization techniques and theoretical calculations,are suggested.展开更多
Methanol to gasoline reaction was investigated on two prepared ZSM-5 catalysts. The first one was a conventional catalyst denoted as ZSM-5（C） and the other was a hierarchical catalyst-ZSM-5（S） which was prepared b...Methanol to gasoline reaction was investigated on two prepared ZSM-5 catalysts. The first one was a conventional catalyst denoted as ZSM-5（C） and the other was a hierarchical catalyst-ZSM-5（S） which was prepared by incorporation of table sugar in catalyst gel during the synthesis procedure. The catalysts were characterized by FTIR, XRD, FE-SEM, N2 adsorption-desorption, NH3-TPD and TGA analytical technics. The proposed material showed pore modification as well as acidity moderating properties in ZSM-5 catalyst. The methanol to gasoline reaction was conducted in a fixed bed reactor with a WHSV of 1.5 h-1.Methanol conversions, gasoline yield and selectivity in production for the synthesized catalysts were determined by gas chromatography method. The sugar modified catalyst converted more methanol than the conventional one and an enhancement in catalyst’s life time was observed. The selectivity to aromatics and durene were reduced compared to the conventional catalyst, so the gasoline quality was also further improved. The coking rate of catalysts was calculated employing TGA method. A reduction in coking rate and an increase in coke capacity of the modified catalyst were observed.展开更多
The CeO2/CuO catalysts using different template agent（F68 L64, F127 and P123） were synthesized by the simple template and impregnation method. They were characterized by FESEM, XRD, N2 physisorption and H2-TPR techn...The CeO2/CuO catalysts using different template agent（F68 L64, F127 and P123） were synthesized by the simple template and impregnation method. They were characterized by FESEM, XRD, N2 physisorption and H2-TPR techniques. It is found that the CeO2/CuO catalysts are double pore distribution, and CeO2 can enter into the gap of CuO supports and form the contact interface of copper and cerium. Among the asprepared catalysts, the CeO2/CuO-F127 catalyst displays better activity at lower temperature and the CeO2/CuO-P123 catalyst presents higher activity at higher temperature. The CeO2/CuO-P123 catalyst has the smallest crystallite sizes of CuO and CeO2 as well as the largest size of cubes, which may improve the interaction of copper and cerium and enhance the performance of CO oxidation.展开更多
As one of the naturally abundant elements,carbon can present in different molecular structures(allotropes)and thus lead to various physi-cal/chemical properties of carbon-based materials which have found wide applicat...As one of the naturally abundant elements,carbon can present in different molecular structures(allotropes)and thus lead to various physi-cal/chemical properties of carbon-based materials which have found wide applications in a variety of fields including electrochemistry,optical,adsorption and catalysis,etc.On the other hand,its different allotropes also endow carbon-based materials with various morphostructures,which have been recently explored to prepare oxides and zeolites/zeotypes with tailored structures.In this review,we mainly summarize the recent advances in using carbon materials as hard templates to synthesize structural materials.Specifically,we focus on the development in the synthetic strategies,such as endotemplating,exotemplating approaches and using carbon materials as chemical reagents for the synthesis of metal carbides or nitrides,with an emphasis laid on the control of morphostructure.Meanwhile,the applications of the obtained materials will be highlighted,especially,in the field of heterogeneous catalysis where enhanced performances have been achieved with the materials derived from carbon-templated methods.展开更多
Existing Chinese named entity recognition(NER)research utilises 1D lexicon-based sequence labelling frameworks,which can only recognise flat entities.While lexicons serve as prior knowledge and enhance semantic inform...Existing Chinese named entity recognition(NER)research utilises 1D lexicon-based sequence labelling frameworks,which can only recognise flat entities.While lexicons serve as prior knowledge and enhance semantic information,they also pose completeness and resource requirements limitations.This paper proposes a template-based classification(TC)model to avoid lexicon issues and to identify nested entities.Template-based classification provides a template word for each entity type,which utilises contrastive learning to integrate the common characteristics among entities with the same category.Contrastive learning makes template words the centre points of their category in the vector space,thus improving generalisation ability.Additionally,TC presents a 2D tablefilling label scheme that classifies entities based on the attention distribution of template words.The proposed novel decoder algorithm enables TC recognition of both flat and nested entities simultaneously.Experimental results show that TC achieves the state-ofthe-art performance on five Chinese datasets.展开更多
A simple and general strategy is described for preparing network supported catalyst through a one-pot synthetic procedure using supramolecular gel as template.This procedure directly attaches ligand to support during ...A simple and general strategy is described for preparing network supported catalyst through a one-pot synthetic procedure using supramolecular gel as template.This procedure directly attaches ligand to support during fabricating the support.Using this strategy,supported CuBr/di-（2-picolyl） amine catalyst with U-shaped fibrillar network was prepared and used in atom transfer radical polymerization of methyl methacrylate.XPS and SEM characterization of the catalyst revealed homogeneous distribution of ligand,sufficient reactive sites,adequate mechanical strength and macroporosity.The polymerization results demonstrated high activity and reusability of such catalyst.This strategy might be extended to other supported catalysts used in column reactors.展开更多
Lithium-ion batteries(LIBs)have dominated the portable electronic and electrochemical energy markets since their commercialisation,whose high cost and lithium scarcity have prompted the development of other alkali-ion...Lithium-ion batteries(LIBs)have dominated the portable electronic and electrochemical energy markets since their commercialisation,whose high cost and lithium scarcity have prompted the development of other alkali-ion batteries(AIBs)including sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).Owing to larger ion sizes of Na^(+)and K^(+)compared with Li^(+),nanocomposites with excellent crystallinity orientation and well-developed porosity show unprecedented potential for advanced lithium/sodium/potassium storage.With enticing open rigid framework structures,Prussian blue analogues(PBAs)remain promising self-sacrificial templates for the preparation of various nanocomposites,whose appeal originates from the well-retained porous structures and exceptional electrochemical activities after thermal decomposition.This review focuses on the recent progress of PBA-derived nanocomposites from their fabrication,lithium/sodium/potassium storage mechanism,and applications in AIBs(LIBs,SIBs,and PIBs).To distinguish various PBA derivatives,the working mechanism and applications of PBA-templated metal oxides,metal chalcogenides,metal phosphides,and other nanocomposites are systematically evaluated,facilitating the establishment of a structure–activity correlation for these materials.Based on the fruitful achievements of PBA-derived nanocomposites,perspectives for their future development are envisioned,aiming to narrow down the gap between laboratory study and industrial reality.展开更多
To realize the commercialize of rechargeable Zn-air battery(RZAB),developing metal-free bifunctional electrocatalysts with satisfactory activity for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is o...To realize the commercialize of rechargeable Zn-air battery(RZAB),developing metal-free bifunctional electrocatalysts with satisfactory activity for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is one of the emerging issues.Herein,a prawn shells-derived N-enriched porous carbon(PSNC)is synthesized via an ion exchange coupled biomimetic selfsacrificing template strategy.The resulting PSNC displays unique functional components,including the interconnected macro-meso-micropores structure to shorten charge and mass transfer pathway,high content of pyridinic and graphitic nitrogen to construct rich catalytic active site and improve conductivity.As electrocatalysts in alkaline condition,the optimized PSNC-0.8 achieves excellent bifunctional catalytic propriety with a narrow potential gap(ΔE)value of 0.80 V.Meanwhile,PSNC-0.8-based RZAB displays a high peak power density of 176.5 mW·cm^(-2)and considerable cycling durability with a small battery efficiency delay of 6.5%after 480 cycles(320 h).This study enlightens a simple and effective conception to design high-performance metal-free bifunctional electrocatalysts from seafood waste.展开更多
Molecular nitrogen is relatively inert and the activation of its triple bond is full of challenges and of significance.Hence,searching for an efficiently heterogeneous catalyst with high stability and dispersion is on...Molecular nitrogen is relatively inert and the activation of its triple bond is full of challenges and of significance.Hence,searching for an efficiently heterogeneous catalyst with high stability and dispersion is one of the important targets of chemical technology.Here,we report a Ba‐K/Ru‐MC catalyst with Ru particle size of 1.5–2.5 nm semi‐embedded in a mesoporous C matrix and with dual promoters of Ba and K that exhibits a higher activity than the supported Ba‐Ru‐K/MC catalyst,although both have similar metal particle sizes for ammonia synthesis.Further,the Ba‐K/Ru‐MC catalyst is more active than commercial fused Fe catalysts and supported Ru catalysts.Characterization techniques such as high‐resolution transmission electron microscopy,N2 physisorption,CO chemisorption,and temperature‐programmed reduction suggest that the Ru nanoparticles have strong interactions with the C matrix in Ba‐K/Ru‐MC,which may facilitate electron transport better than supported nanoparticles.展开更多
Through employing zeolitic imidazolate framework-67(ZIF-67)templates,the straightforward hydrother-mal and electrodeposition methods were applied to synthesize FeOOH@CoMoO_(4)heterostructure attached to the sur-face o...Through employing zeolitic imidazolate framework-67(ZIF-67)templates,the straightforward hydrother-mal and electrodeposition methods were applied to synthesize FeOOH@CoMoO_(4)heterostructure attached to the sur-face of nickel foam(NF).The specific structure of the as-prepared FeOOH@CoMoO_(4)/NF-400s provided pronounced porosity and extensive surface area,enhancing rapid electron transport and exposing abundant active sites to improve catalytic reactions.Furthermore,the introduction of FeOOH,which induces electron transfer from FeOOH to CoMoO_(4),confirms their strong electronic interaction,thereby leading to an accelerated surface catalytic reaction.Consequently,the constructed FeOOH@CoMoO_(4)/NF-400s heterostructure demonstrated exceptional oxygen evolu-tion reaction(OER)activity,requiring an overpotential of 199 mV to deliver the current density of 10 mA·cm^(-2),cou-pled with the superior Tafel slope value of 49.56 mV·dec^(-1)and outstanding stability over 20 h under the current densities of both 10 and 100 mA·cm^(-2).展开更多
The wide band gap characteristics of gallium oxide make it very suitable for the preparation of solar-blind ultra-violet photodetectors.The responsivity of ultraviolet photodetectors based on thin films is often low.H...The wide band gap characteristics of gallium oxide make it very suitable for the preparation of solar-blind ultra-violet photodetectors.The responsivity of ultraviolet photodetectors based on thin films is often low.However,nanomaterials have excellent photoelectric properties in device applications due to the high stability brought by high specific surface area and high crystal quality.Here,we successfully depositedβ-Ga_(2)O_(3) nanopores on the double-pass ordered porous AAO tem-plate by PLD.The porous AAO template is used as the growth space of nanomaterials,and the gallium oxide material is filled into the pores of the template to form a nanotube structure.By optimizing the preparation process,the relationship be-tween the performance of gallium oxide nanopores and the growth time was studied in depth.With the increase of growth time,the responsivity of the detector was improved.The rise timeτr=0.7 s,the decay timeτ_(d)=1.3 s,and the responsivity reached 4.63 mA·W^(-1),which was higher than 2.24 mA·W^(-1)of the responsivity of silicon-based gallium oxide nanorods.展开更多
In the present work,the high uniform 6-inch single-crystalline AlN template is successfully achieved by high temperature annealing technique,which opens up the path towards industrial application in power device.Moreo...In the present work,the high uniform 6-inch single-crystalline AlN template is successfully achieved by high temperature annealing technique,which opens up the path towards industrial application in power device.Moreover,the outstanding crystalline-quality is confirmed by Rutherford backscattering spectrometry(RBS).In accompanied with the results from X-ray diffraction,the RBS results along both[0001]and[1213]reveal that the in-plane lattice is effectively reordered by high temperature annealing.In addition,the constantΦ_(epi)angle between[0001]and[1213]at different depths of 31.54°confirms the uniform compressive strain inside the AlN region.Benefitting from the excellent crystalline quality of AlN template,we can epitaxially grow the enhanced-mode high electron mobility transistor(HEMT)with a graded AlGaN buffer as thin as only~300 nm.Such an ultra-thin AlGaN buffer layer results in the wafer-bow as low as 18.1μm in 6-inch wafer scale.The fabricated HEMT devices with 16μm-L_(GD)exhibits a threshold voltage(V_(TH))of 1.1 V and a high OFF-state breakdown voltage(V_(BD))over 1400 V.Furthermore,after 200 V high-voltage OFF-state stress,the current collapse is only 13.6%.Therefore,the advantages of both 6-inch size and excellent crystallinity announces the superiority of single-crystalline AlN template in low-cost electrical power applications.展开更多
Ti-containing mesoporous silica materials(Ti-MSs) with isolated tetrahedrally coordinated Ti species have been widely applied in bulk molecular catalysis. Herein, Ti-MSs were synthesized using anionic surfactant SDS a...Ti-containing mesoporous silica materials(Ti-MSs) with isolated tetrahedrally coordinated Ti species have been widely applied in bulk molecular catalysis. Herein, Ti-MSs were synthesized using anionic surfactant SDS as the co-template. The SDS molecular assembled structures can interact with silica species through the interface hydrogen bonds leading to the formation of mesoporous silica structure with compact Ti-O bonds, lower hydrophilicity and low template cost. The influence of adding SDS as the co-template on the oxidation of styrene with aqueous H_2O_2 as the oxidant was investigated. Ti-MSs using SDS as the co-template showed better catalytic performance as compared with mesoporous titanium silicate synthesized with CTAB serving as the sole template. Moreover, the Ti-MSs synthesized at a Ti/Si ratio of 0.005 demonstrated an optimized performance for styrene oxidation with styrene conversion improved by 14.8%, benzaldehyde selectivity improved by 13.7% and styrene oxide selectivity improved by 9.2% when the reaction time was 6 h.展开更多
Corn starch was used as a templating agent,and an oxide mixture containing alumina,magnesia,zirconia and yttria was added in the sol-gel state.After slip casting,curing at 85℃,drying and sintering,high-performance po...Corn starch was used as a templating agent,and an oxide mixture containing alumina,magnesia,zirconia and yttria was added in the sol-gel state.After slip casting,curing at 85℃,drying and sintering,high-performance porous alumina ceramics were obtained.The properties of the porous alumina ceramics were analyzed by means of SEM,XRD,flexural strength and porosity.The research findings showed that,when the starch content was 1 wt%,the prepared ceramic mainly consisted of four phases:α-Al_(2)O_(3),MgAl_(2)O_(4),ZrO,and YSZ.The flexural strength reached 157.27 MPa,the flexural strength of the green body was about 3 MPa,and the porosity was around 30%.展开更多
Proton exchange membrane fuel cells suffer from the sluggish kinetics of the oxygen reduction reaction(ORR)and the high cost of Pt catalysts.In the present work,a high‐performance ORR catalystbased on Fe,N,S‐doped p...Proton exchange membrane fuel cells suffer from the sluggish kinetics of the oxygen reduction reaction(ORR)and the high cost of Pt catalysts.In the present work,a high‐performance ORR catalystbased on Fe,N,S‐doped porous carbon(FeNS‐PC)was synthesized using melamine formaldehyderesin as C and N precursors,Fe(SCN)3as Fe and S precursors,and CaCl2as a template via a two‐stepheat treatment without a harsh template removal step.The results show that the catalyst treated at900℃(FeNS‐PC‐900)had a high surface area of775m2/g,a high mass activity of10.2A/g in anacidic medium,and excellent durability;the half‐wave potential decreased by only20mV after10000potential cycles.The FeNS‐PC‐900catalyst was used as the cathode in a proton exchangemembrane fuel cell and delivered a peak power density of0.49W/cm2.FeNS‐PC‐900therefore hasgood potential for use in practical applications.展开更多
With the rapid development of Internet of things technology,the efficiency of data transmission between devices has been significantly improved.However,the open network environment also poses serious security risks.Th...With the rapid development of Internet of things technology,the efficiency of data transmission between devices has been significantly improved.However,the open network environment also poses serious security risks.This paper proposes an innovative fingerprint template protection scheme,which generates key streams through an improved fourdimensional superchaotic system(4CSCS),uses the space-filling property of Hilbert curves to achieve pixel scrambling,and introduces dynamic DNA encoding to improve encryption.Experimental results show that this scheme has a large key space 2^(528),encrypts image information entropy of more than 7.9970,and shows excellent performance in defending against statistical attacks and differential attacks.Compared with existing methods,this scheme has significant advantages in terms of encryption performance and security,and provides a reliable protection mechanism for fingerprint authentication systems in the Internet of things environment.展开更多
The Mg−1Zn−1Sn and Mg−1Zn−1Sn−0.2Ca alloy scaffolds were prepared via infiltration casting using 3D-printed Ti templates to achieve complete and accurate control of the pore structure.The results indicate that the act...The Mg−1Zn−1Sn and Mg−1Zn−1Sn−0.2Ca alloy scaffolds were prepared via infiltration casting using 3D-printed Ti templates to achieve complete and accurate control of the pore structure.The results indicate that the actual porosity and pore size of the prepared P model for each pore size are greater than the designed values.The addition of Ca changes the second phase of the alloy from Mg_(2)Sn to CaMgSn and refines its microstructure.The compressive yield strength and compressive modulus of the Mg−1Zn−1Sn−0.2Ca alloy scaffold reach 32.61 MPa and 0.23 GPa,respectively.The corrosion current density is measured at 14.64μA/cm^(2),with an instantaneous corrosion rate of 0.335 mm/a.Both scaffolds exhibit excellent biocompatibility and no cytotoxicity.Additionally,the antibacterial effects of both alloys on E.coli are greater than 97.81%.These results indicate that Mg alloy scaffolds have great potential for clinical applications.展开更多
基金supported by the National Key R&D Program of China (Grant No. 2022YFB3605000)the National Natural Science Foundation of China (Nos. 62004127, 61725403, 62121005, 61922078, 61827813, and 62004196)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciencesthe Youth Talent Promotion Project of the Chinese Institute of Electronics (No. 2020QNRC001)。
文摘High-temperature-annealed Al N(HTA-Al N) templates provide ideal substrates for high-quality Al Ga N epitaxy. However, the significant compressive stress accumulated within the Al Ga N layer makes it challenging to achieve a smooth surface free of hexagonal hillocks on these templates. To address this issue, we investigate the mechanism of compressive stress accumulation during the growth of Al Ga N-based epilayers on HTA-Al N templates using in-situ curvature analysis in this study. To verify the mechanism, a low-Al-content Al Ga N interlayer is introduced between the Al N epilayer and the subsequent Al Ga N epilayer. The larger a-plane lattice constant of this interlayer relative to the Al Ga N epilayer slows the accumulation rate of compressive stress. The hexagonal hillock can be effectively suppressed and the surface of Al Ga N epilayer can be significantly regulated by adopting various low-Al-content Al Ga N interlayers. This work provides a comprehension on the stress accumulation mechanism in Al Ga N epilayers and a feasible method to obtain hillock-free surface of Al Ga N epilayers on HTA-Al N templates,which will be beneficial for fabricating Al Ga N based devices.
基金financially supported by the National Natural Science Foundation of China(22271021,21971024,and 22201021)the Natural Science Foundation and Education Department of Liaoning Province(LJ232410167011)。
文摘Enhancing the catalytic activity of catalysts is a core objective in their design and synthesis processes,and the accessibility of active sites is one of the crucial factors determining catalyst activity.Polyoxometalate-based metal-organic complexes(POMOCs)with well-defined structures,which combine the advantages of POMs and MOCs,may offer the possibility to construct catalysts with highly accessible active sites.In this study,a series of POMOCs were successfully designed and synthesized using different POM templates,including[CoII1.5(L)1.5(PMo12O40)(H_(2)O)4]·3H_(2)O(Co-PMo12),[CoII1.5(L)1.5(PW12O40)(H_(2)O)4]·3H_(2)O(Co-PW12),[CoII2(L)2-(SiW12O40)(H_(2)O)4]·11H_(2)O(Co-SiW12),and H[CoII2.5(L)3-(P2W18O62)(H_(2)O)8]·10H_(2)O(Co-P2W18),which were characterized by Fourier transform infrared spectroscopy,powder X-ray diffraction,and single crystal X-ray diffraction.The differences in catalytic activity among the four POMOCs for olefin epoxidation were attributed to the distinct accessibility of Co(II)sites upon thermal activation.Among them,Co-P2W18 achieved a remarkable 99%yield of 1,2-epoxycyclooctane within 3 h at room temperature using O_(2)as the oxidant,owing to its highly accessible unsaturated Co(II)sites.Co-P2W18 exhibits significantly superior catalytic activity for the cyclooctene epoxidation reaction compared to most reported catalysts.Additionally,the reaction mechanism was investigated using density functional theory.
基金supported by the National Natural Science Foundation of China (grant no.21201130)Foundation of State Key Laboratory of Coal Conversion,China (J14-15-603)+1 种基金China Scholarship Council (CSC no.:201406895017)Shanghai Education Commission Innovation Project (14YZ016)
文摘Nano hierarchical mesoporous ZSM-5 catalysts were prepared with cationic dimethyldiallyl ammonium chloride acrylamide copolymer（PDDA） as a soft second template. Using ZSM-5 catalyst as a matrix,Zn/ZSM-5 catalysts were also obtained by the wet impregnation method. The effect of the PDDA amount and Zn loadings on the properties of the catalysts,including crystallinity,morphology,textural properties,acid nature and catalytic activity in MTG reaction,was investigated by XRD,FESEM,TEM,Nitrogen adsorption–desorption isotherms and NH3-TPD method,respectively. The MTG reaction was performed in a fixed bed reactor,and the result revealed that the nano hierarchical ZSM-5 catalyst prepared with a PDDA/Si molar ratio of 0.070 possesses longer stable phase of 70 h with a liquid hydrocarbon selectivity of 29.8%.Zn/ZSM-5 catalyst with a Zn/ZSM-5 ratio of 0.07 wt.% shows the highest liquid hydrocarbon selectivity,reaching 62.5%.
基金the support from the CIPHER Project(IIID 2018-008)funded by the Commission on Higher Education-Philippine California Advanced Research Institutes(CHED-PCARI)。
文摘Transition metal phosphides(TMPs)have been regarded as alternative hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts owing to their comparable activity to those of noble metal-based catalysts.TMPs have been produced in various morphologies,including hollow and porous nanostructures,which are features deemed desirable for electrocatalytic materials.Templated synthesis routes are often responsible for such morphologies.This paper reviews the latest advances and existing challenges in the synthesis of TMP-based OER and HER catalysts through templated methods.A comprehensive review of the structure-property-performance of TMP-based HER and OER catalysts prepared using different templates is presented.The discussion proceeds according to application,first by HER and further divided among the types of templates used-from hard templates,sacrificial templates,and soft templates to the emerging dynamic hydrogen bubble template.OER catalysts are then reviewed and grouped according to their morphology.Finally,prospective research directions for the synthesis of hollow and porous TMP-based catalysts,such as improvements on both activity and stability of TMPs,design of environmentally benign templates and processes,and analysis of the reaction mechanism through advanced material characterization techniques and theoretical calculations,are suggested.
基金the Petrochemical Research and Technology Company, Tehran, Iran for financial support of this research
文摘Methanol to gasoline reaction was investigated on two prepared ZSM-5 catalysts. The first one was a conventional catalyst denoted as ZSM-5（C） and the other was a hierarchical catalyst-ZSM-5（S） which was prepared by incorporation of table sugar in catalyst gel during the synthesis procedure. The catalysts were characterized by FTIR, XRD, FE-SEM, N2 adsorption-desorption, NH3-TPD and TGA analytical technics. The proposed material showed pore modification as well as acidity moderating properties in ZSM-5 catalyst. The methanol to gasoline reaction was conducted in a fixed bed reactor with a WHSV of 1.5 h-1.Methanol conversions, gasoline yield and selectivity in production for the synthesized catalysts were determined by gas chromatography method. The sugar modified catalyst converted more methanol than the conventional one and an enhancement in catalyst’s life time was observed. The selectivity to aromatics and durene were reduced compared to the conventional catalyst, so the gasoline quality was also further improved. The coking rate of catalysts was calculated employing TGA method. A reduction in coking rate and an increase in coke capacity of the modified catalyst were observed.
基金Project supported by the National Natural Science Foundation of China(21466024)the Natural Science Foundation of Inner Mongolia(2014MS0217,2015MS0209)
文摘The CeO2/CuO catalysts using different template agent（F68 L64, F127 and P123） were synthesized by the simple template and impregnation method. They were characterized by FESEM, XRD, N2 physisorption and H2-TPR techniques. It is found that the CeO2/CuO catalysts are double pore distribution, and CeO2 can enter into the gap of CuO supports and form the contact interface of copper and cerium. Among the asprepared catalysts, the CeO2/CuO-F127 catalyst displays better activity at lower temperature and the CeO2/CuO-P123 catalyst presents higher activity at higher temperature. The CeO2/CuO-P123 catalyst has the smallest crystallite sizes of CuO and CeO2 as well as the largest size of cubes, which may improve the interaction of copper and cerium and enhance the performance of CO oxidation.
基金supported by the National Natural Science Foundation of China(21006024)Shanghai Key Laboratory of Molecular Catalysts and Innovative Materials,Department of Chemistry,Fudan University(No.2010MCIMKF)+2 种基金Fundamental Research Funds for the Central Universities(WA0914023)CPNP Foundation(2011D-5006-0507)sponsored by the Shanghai Pujiang Program(11PJ1402600)for talented returnees
文摘As one of the naturally abundant elements,carbon can present in different molecular structures(allotropes)and thus lead to various physi-cal/chemical properties of carbon-based materials which have found wide applications in a variety of fields including electrochemistry,optical,adsorption and catalysis,etc.On the other hand,its different allotropes also endow carbon-based materials with various morphostructures,which have been recently explored to prepare oxides and zeolites/zeotypes with tailored structures.In this review,we mainly summarize the recent advances in using carbon materials as hard templates to synthesize structural materials.Specifically,we focus on the development in the synthetic strategies,such as endotemplating,exotemplating approaches and using carbon materials as chemical reagents for the synthesis of metal carbides or nitrides,with an emphasis laid on the control of morphostructure.Meanwhile,the applications of the obtained materials will be highlighted,especially,in the field of heterogeneous catalysis where enhanced performances have been achieved with the materials derived from carbon-templated methods.
基金Sichuan Provincial Science and Technology Support Program,Grant/Award Number:2023YFG0151National Natural Science Foundation of China,Grant/Award Numbers:U22B2061,U2336204。
文摘Existing Chinese named entity recognition(NER)research utilises 1D lexicon-based sequence labelling frameworks,which can only recognise flat entities.While lexicons serve as prior knowledge and enhance semantic information,they also pose completeness and resource requirements limitations.This paper proposes a template-based classification(TC)model to avoid lexicon issues and to identify nested entities.Template-based classification provides a template word for each entity type,which utilises contrastive learning to integrate the common characteristics among entities with the same category.Contrastive learning makes template words the centre points of their category in the vector space,thus improving generalisation ability.Additionally,TC presents a 2D tablefilling label scheme that classifies entities based on the attention distribution of template words.The proposed novel decoder algorithm enables TC recognition of both flat and nested entities simultaneously.Experimental results show that TC achieves the state-ofthe-art performance on five Chinese datasets.
基金support from the National Natural Science Foundation of China(Nos.20574041 and 20874055)Hi-tech Research and Development Program(863 plan) of China(No.2009AA062903)
文摘A simple and general strategy is described for preparing network supported catalyst through a one-pot synthetic procedure using supramolecular gel as template.This procedure directly attaches ligand to support during fabricating the support.Using this strategy,supported CuBr/di-（2-picolyl） amine catalyst with U-shaped fibrillar network was prepared and used in atom transfer radical polymerization of methyl methacrylate.XPS and SEM characterization of the catalyst revealed homogeneous distribution of ligand,sufficient reactive sites,adequate mechanical strength and macroporosity.The polymerization results demonstrated high activity and reusability of such catalyst.This strategy might be extended to other supported catalysts used in column reactors.
基金financial support from the Special Funds for the Cultivation of Guangdong College Students’Scientific and Technological Innovation(“Climbing Program”Special Funds,pdjh2023b0145)the Scientific Research Innovation Project of Graduate School of South China Normal University(2024KYLX047)financial support from the Australian Research Council,Centre for Materials Science,Queensland University of Technology.
文摘Lithium-ion batteries(LIBs)have dominated the portable electronic and electrochemical energy markets since their commercialisation,whose high cost and lithium scarcity have prompted the development of other alkali-ion batteries(AIBs)including sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).Owing to larger ion sizes of Na^(+)and K^(+)compared with Li^(+),nanocomposites with excellent crystallinity orientation and well-developed porosity show unprecedented potential for advanced lithium/sodium/potassium storage.With enticing open rigid framework structures,Prussian blue analogues(PBAs)remain promising self-sacrificial templates for the preparation of various nanocomposites,whose appeal originates from the well-retained porous structures and exceptional electrochemical activities after thermal decomposition.This review focuses on the recent progress of PBA-derived nanocomposites from their fabrication,lithium/sodium/potassium storage mechanism,and applications in AIBs(LIBs,SIBs,and PIBs).To distinguish various PBA derivatives,the working mechanism and applications of PBA-templated metal oxides,metal chalcogenides,metal phosphides,and other nanocomposites are systematically evaluated,facilitating the establishment of a structure–activity correlation for these materials.Based on the fruitful achievements of PBA-derived nanocomposites,perspectives for their future development are envisioned,aiming to narrow down the gap between laboratory study and industrial reality.
基金financially supported by the Innovative Youth Talents of Guangdong Education Department Support Program(No.2021KQNCX027)the Youth Innovative Talents Project of Zhanjiang(No.2021E05016)the Program forScientific Research Start-Up Funds of Guangdong Ocean University(Nos.060302122010 and R19047)。
文摘To realize the commercialize of rechargeable Zn-air battery(RZAB),developing metal-free bifunctional electrocatalysts with satisfactory activity for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is one of the emerging issues.Herein,a prawn shells-derived N-enriched porous carbon(PSNC)is synthesized via an ion exchange coupled biomimetic selfsacrificing template strategy.The resulting PSNC displays unique functional components,including the interconnected macro-meso-micropores structure to shorten charge and mass transfer pathway,high content of pyridinic and graphitic nitrogen to construct rich catalytic active site and improve conductivity.As electrocatalysts in alkaline condition,the optimized PSNC-0.8 achieves excellent bifunctional catalytic propriety with a narrow potential gap(ΔE)value of 0.80 V.Meanwhile,PSNC-0.8-based RZAB displays a high peak power density of 176.5 mW·cm^(-2)and considerable cycling durability with a small battery efficiency delay of 6.5%after 480 cycles(320 h).This study enlightens a simple and effective conception to design high-performance metal-free bifunctional electrocatalysts from seafood waste.
基金supported by the National Natural Science Foundation of China(20803064)the Natural Science Foundation of Zhejiang Provence(LY17B030010)~~
文摘Molecular nitrogen is relatively inert and the activation of its triple bond is full of challenges and of significance.Hence,searching for an efficiently heterogeneous catalyst with high stability and dispersion is one of the important targets of chemical technology.Here,we report a Ba‐K/Ru‐MC catalyst with Ru particle size of 1.5–2.5 nm semi‐embedded in a mesoporous C matrix and with dual promoters of Ba and K that exhibits a higher activity than the supported Ba‐Ru‐K/MC catalyst,although both have similar metal particle sizes for ammonia synthesis.Further,the Ba‐K/Ru‐MC catalyst is more active than commercial fused Fe catalysts and supported Ru catalysts.Characterization techniques such as high‐resolution transmission electron microscopy,N2 physisorption,CO chemisorption,and temperature‐programmed reduction suggest that the Ru nanoparticles have strong interactions with the C matrix in Ba‐K/Ru‐MC,which may facilitate electron transport better than supported nanoparticles.
文摘Through employing zeolitic imidazolate framework-67(ZIF-67)templates,the straightforward hydrother-mal and electrodeposition methods were applied to synthesize FeOOH@CoMoO_(4)heterostructure attached to the sur-face of nickel foam(NF).The specific structure of the as-prepared FeOOH@CoMoO_(4)/NF-400s provided pronounced porosity and extensive surface area,enhancing rapid electron transport and exposing abundant active sites to improve catalytic reactions.Furthermore,the introduction of FeOOH,which induces electron transfer from FeOOH to CoMoO_(4),confirms their strong electronic interaction,thereby leading to an accelerated surface catalytic reaction.Consequently,the constructed FeOOH@CoMoO_(4)/NF-400s heterostructure demonstrated exceptional oxygen evolu-tion reaction(OER)activity,requiring an overpotential of 199 mV to deliver the current density of 10 mA·cm^(-2),cou-pled with the superior Tafel slope value of 49.56 mV·dec^(-1)and outstanding stability over 20 h under the current densities of both 10 and 100 mA·cm^(-2).
文摘The wide band gap characteristics of gallium oxide make it very suitable for the preparation of solar-blind ultra-violet photodetectors.The responsivity of ultraviolet photodetectors based on thin films is often low.However,nanomaterials have excellent photoelectric properties in device applications due to the high stability brought by high specific surface area and high crystal quality.Here,we successfully depositedβ-Ga_(2)O_(3) nanopores on the double-pass ordered porous AAO tem-plate by PLD.The porous AAO template is used as the growth space of nanomaterials,and the gallium oxide material is filled into the pores of the template to form a nanotube structure.By optimizing the preparation process,the relationship be-tween the performance of gallium oxide nanopores and the growth time was studied in depth.With the increase of growth time,the responsivity of the detector was improved.The rise timeτr=0.7 s,the decay timeτ_(d)=1.3 s,and the responsivity reached 4.63 mA·W^(-1),which was higher than 2.24 mA·W^(-1)of the responsivity of silicon-based gallium oxide nanorods.
基金supported by the National Key R&D Program of China(No.2022YFE0140100)the National Natural Science Foundation of China(Nos.52273271 and 62321004)partly supported by the Key R&D Program of Guangdong Province(No.2020B01074003)。
文摘In the present work,the high uniform 6-inch single-crystalline AlN template is successfully achieved by high temperature annealing technique,which opens up the path towards industrial application in power device.Moreover,the outstanding crystalline-quality is confirmed by Rutherford backscattering spectrometry(RBS).In accompanied with the results from X-ray diffraction,the RBS results along both[0001]and[1213]reveal that the in-plane lattice is effectively reordered by high temperature annealing.In addition,the constantΦ_(epi)angle between[0001]and[1213]at different depths of 31.54°confirms the uniform compressive strain inside the AlN region.Benefitting from the excellent crystalline quality of AlN template,we can epitaxially grow the enhanced-mode high electron mobility transistor(HEMT)with a graded AlGaN buffer as thin as only~300 nm.Such an ultra-thin AlGaN buffer layer results in the wafer-bow as low as 18.1μm in 6-inch wafer scale.The fabricated HEMT devices with 16μm-L_(GD)exhibits a threshold voltage(V_(TH))of 1.1 V and a high OFF-state breakdown voltage(V_(BD))over 1400 V.Furthermore,after 200 V high-voltage OFF-state stress,the current collapse is only 13.6%.Therefore,the advantages of both 6-inch size and excellent crystallinity announces the superiority of single-crystalline AlN template in low-cost electrical power applications.
基金financially supported by the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents (No. 2014RCJJ017)
文摘Ti-containing mesoporous silica materials(Ti-MSs) with isolated tetrahedrally coordinated Ti species have been widely applied in bulk molecular catalysis. Herein, Ti-MSs were synthesized using anionic surfactant SDS as the co-template. The SDS molecular assembled structures can interact with silica species through the interface hydrogen bonds leading to the formation of mesoporous silica structure with compact Ti-O bonds, lower hydrophilicity and low template cost. The influence of adding SDS as the co-template on the oxidation of styrene with aqueous H_2O_2 as the oxidant was investigated. Ti-MSs using SDS as the co-template showed better catalytic performance as compared with mesoporous titanium silicate synthesized with CTAB serving as the sole template. Moreover, the Ti-MSs synthesized at a Ti/Si ratio of 0.005 demonstrated an optimized performance for styrene oxidation with styrene conversion improved by 14.8%, benzaldehyde selectivity improved by 13.7% and styrene oxide selectivity improved by 9.2% when the reaction time was 6 h.
文摘Corn starch was used as a templating agent,and an oxide mixture containing alumina,magnesia,zirconia and yttria was added in the sol-gel state.After slip casting,curing at 85℃,drying and sintering,high-performance porous alumina ceramics were obtained.The properties of the porous alumina ceramics were analyzed by means of SEM,XRD,flexural strength and porosity.The research findings showed that,when the starch content was 1 wt%,the prepared ceramic mainly consisted of four phases:α-Al_(2)O_(3),MgAl_(2)O_(4),ZrO,and YSZ.The flexural strength reached 157.27 MPa,the flexural strength of the green body was about 3 MPa,and the porosity was around 30%.
基金supported by the National Basic Research Program of China (973 Program,2015CB932303)the National Natural Science Founda-tion of China (21373175,21621091)~~
文摘Proton exchange membrane fuel cells suffer from the sluggish kinetics of the oxygen reduction reaction(ORR)and the high cost of Pt catalysts.In the present work,a high‐performance ORR catalystbased on Fe,N,S‐doped porous carbon(FeNS‐PC)was synthesized using melamine formaldehyderesin as C and N precursors,Fe(SCN)3as Fe and S precursors,and CaCl2as a template via a two‐stepheat treatment without a harsh template removal step.The results show that the catalyst treated at900℃(FeNS‐PC‐900)had a high surface area of775m2/g,a high mass activity of10.2A/g in anacidic medium,and excellent durability;the half‐wave potential decreased by only20mV after10000potential cycles.The FeNS‐PC‐900catalyst was used as the cathode in a proton exchangemembrane fuel cell and delivered a peak power density of0.49W/cm2.FeNS‐PC‐900therefore hasgood potential for use in practical applications.
文摘With the rapid development of Internet of things technology,the efficiency of data transmission between devices has been significantly improved.However,the open network environment also poses serious security risks.This paper proposes an innovative fingerprint template protection scheme,which generates key streams through an improved fourdimensional superchaotic system(4CSCS),uses the space-filling property of Hilbert curves to achieve pixel scrambling,and introduces dynamic DNA encoding to improve encryption.Experimental results show that this scheme has a large key space 2^(528),encrypts image information entropy of more than 7.9970,and shows excellent performance in defending against statistical attacks and differential attacks.Compared with existing methods,this scheme has significant advantages in terms of encryption performance and security,and provides a reliable protection mechanism for fingerprint authentication systems in the Internet of things environment.
基金the financial support for this work from the National Natural Science Foundation of China(Nos.52171241,52373251,52201301,51801137)Natural Science Foundation of Tianjin City,China(No.22JCQNJC00750)Tianjin University of Technology Graduate Research Innovation Project,China(No.YJ2235)。
文摘The Mg−1Zn−1Sn and Mg−1Zn−1Sn−0.2Ca alloy scaffolds were prepared via infiltration casting using 3D-printed Ti templates to achieve complete and accurate control of the pore structure.The results indicate that the actual porosity and pore size of the prepared P model for each pore size are greater than the designed values.The addition of Ca changes the second phase of the alloy from Mg_(2)Sn to CaMgSn and refines its microstructure.The compressive yield strength and compressive modulus of the Mg−1Zn−1Sn−0.2Ca alloy scaffold reach 32.61 MPa and 0.23 GPa,respectively.The corrosion current density is measured at 14.64μA/cm^(2),with an instantaneous corrosion rate of 0.335 mm/a.Both scaffolds exhibit excellent biocompatibility and no cytotoxicity.Additionally,the antibacterial effects of both alloys on E.coli are greater than 97.81%.These results indicate that Mg alloy scaffolds have great potential for clinical applications.
