The quantum anomalous Hall(QAH) effect has attracted enormous attention since it can induce topologically protected conducting edge states in an intrinsic insulating material. For practical quantum applications, the m...The quantum anomalous Hall(QAH) effect has attracted enormous attention since it can induce topologically protected conducting edge states in an intrinsic insulating material. For practical quantum applications, the main obstacle is the non-existent room temperature QAH systems, especially with both large topological band gap and robust ferromagnetic order. Here, according to first-principles calculations, we predict the realization of the room temperature QAH effect in a two-dimensional(2D) honeycomb lattice, RuCS_(3) with a non-zero Chern number of C = 1. Especially, the nontrivial topology band gap reaches up to 336 me V for RuCS_(3). Moreover, we find that RuCS_(3) has a large magnetic anisotropy energy(2.065 me V) and high Curie temperature(696 K). We further find that the non-trivial topological properties are robust against the biaxial strain. The robust topological and magnetic properties make RuCS_(3) have great applications in room temperature spintronics and nanoelectronics.展开更多
This paper presents the catalytic effect of NaH doped nanocrystalline TiO_(2)(designated as NaTiOxH)in the improvement of MgH_(2)hydrogen storage properties.The catalyst preparation involves ball milling NaH with TiO_...This paper presents the catalytic effect of NaH doped nanocrystalline TiO_(2)(designated as NaTiOxH)in the improvement of MgH_(2)hydrogen storage properties.The catalyst preparation involves ball milling NaH with TiO_(2)for 3 hr.The addition of 5 wt%NaTiOxH powder into MgH_(2)reduces its operating temperature to∼185℃,which is∼110℃lower than the additive-free as-milled MgH_(2).The composite remarkably desorbs∼7.2 wt%H_(2)within 15 min at∼290℃and reabsorbs∼4.5 wt%H_(2)in 45 min at room temperature under 50 bar H_(2).MgH_(2)dehydrogenation is activated at 57 kJ/mol by the catalyst.More importantly,the addition of 2.5 wt%NaTiOxH catalyst aids MgH_(2)to reversibly produce∼6.1 wt%H_(2)upon 100 cycles within 475 hr at 300℃.Microstructural investigation into the catalyzed MgH_(2)composite reveals a firm contact existing between NaTiOxH and MgH_(2)particles.Meanwhile,the NaTiOxH catalyst consists of catalytically active Ti_(3)O_(5),and“rod-like”Na_(2)Ti_(3)O_(7)species liberated in-situ during preparation;these active species could provide multiple hydrogen diffusion pathways for an improved MgH_(2)sorption process.Furthermore,the elemental characterization identifies the reduced valence states of titanium(Ti<4+)which show some sort of reversibility consistent with H_(2)insertion and removal.This phenomenon is believed to enhance the mobility of Mg/MgH_(2)electrons by the creation and elimination of oxygen vacancies in the defective(TiO_(2-x))catalyst.Our findings have therefore moved MgH_(2)closer to practical applications.展开更多
A heterojunction structure design is a very good method for improving the properties of semiconductors in many research fields.This method is employed in the present study to promote the gas-sensing performance of Ag_...A heterojunction structure design is a very good method for improving the properties of semiconductors in many research fields.This method is employed in the present study to promote the gas-sensing performance of Ag_(3)PO_(4)nanocomposites at room temperature(25℃).A nanocomposite of Ag_(3)PO_(4)nanoparticles and three-dimensional peony-like WO_(3)(WO_(3)/Ag_(3)PO_(4))was successfully prepared by the precipitation method.The crystalline phases were analyzed by xray diffraction and the microstructure was characterized by scanning electron microscopy and transmission electron microscopy.The chemical bonding states were analyzed by x-ray photoelectron spectroscopy.The gas-sensing performance of WO_(3)/Ag_(3)PO_(4)sensors was systematically explored at room temperature.The composite sensors possessed a higher response and lower detection limit(1 ppm)to NH_(3)than those made of a single type of material;this is ascribed to the synergistic effect achieved by the heterojunction structure.Among the different composite sensors tested,gas sensor A5W5(Ag_(3)PO_(4):WO3mass ratio of 5:5)displayed the highest response to NH_(3)at room temperature.Interestingly,the A5W5 gas sensor exhibited relatively good stability and excellent selectivity to NH_(3).The A5W5 sensor also displayed a relatively good response under high humidity.The gas-sensing mechanism of the WO_(3)/Ag_(3)PO_(4)sensors is explained in detail.Taken together,the as-prepared sensor is highly efficient at detecting NH_(3)and could be suitable for practical applications.In addition,this study also provides a new method for developing Ag_(3)PO_(4)-based sensors in the gas-sensing field.展开更多
1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralo...1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralone is still a big challenge with low-temperature processes using environmentally friendly routes even after decades of research. Herein, we demonstrate room-temperature oxidation of tetralin to 1-tetralone over layered double hydroxide-hosted sulphonato-salen-nickel(II) complex, LDH-[Ni-salen]. The layered double hydroxide-hosted sulphonato-salen-nickel(II) compound was characterized by powder X-ray diffraction, Fourier transform infrared spectrometer (FTIR), UV-Visible diffuse reflectance spectra, scanning electron microscopy (SEM) and elemental analysis. The theoretical calculations of free sulphonato-salen-nickel(II) complex using Density Functional Theory/CAM-B3LYP at the 6-311++ G(d,p) level of theory were also used to determine the orientation of the Ni-salen compound within the layered structure. The immobilized compound, LDH-[Ni-salen] was found to be an effective reusable catalyst for the oxidation of tetralin to 1-tetralone using a combination of trimethylacetaldehyde and molecular oxygen (14.5 psi) and at 25°C. At 45.5% conversion, tetralin was converted to 1-tetralone with 77.2% selectivity at room temperature and atmospheric pressure after 24 h. The catalyst recycles test and hot filtration experiment showed that oxidation proceeded through Ni(II) sites in LDH-[Ni-salen]. The catalysts were reused several times without losing their catalytic activity and selectivity. The present results may provide a convenient strategy for the preparation of 1-tetralone using layered double hydroxide-based heterogeneous catalyst at ambient temperature for industrial application in near future.展开更多
Nano-sized cerium-titanium pyrophosphates Ce1-xTixP2O7 (with x = 0, 0.2, 0.5, 0.7, 0.9, and 1.0) were obtained by grinding a mixture of Ce(SO4)2·4H2O, Ti(SO4)2, and Na4P2O7·10H2O in the presence of sur...Nano-sized cerium-titanium pyrophosphates Ce1-xTixP2O7 (with x = 0, 0.2, 0.5, 0.7, 0.9, and 1.0) were obtained by grinding a mixture of Ce(SO4)2·4H2O, Ti(SO4)2, and Na4P2O7·10H2O in the presence of surfactant PEG-400 at room temperature, washing the mixture with water to remove soluble inorganic salts, and drying at 100℃. The products and their calcined samples were characterized using ultraviolet-visible spectroscopy (UV-vis), thermogravimetry and differential thermal analyses (TG/DTA), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). The results show that nano-sized Ce1-xTixP2O7 behave as an excellent UV-shielding material. Thereinto, the CeP2O7 has the most excellent UV-shielding effect, and the amorphous state of Ce0.8Ti0.2P2O7 can keep at a higher temperature than CeP2O7. Therefore, the stabilization of the amorphous state of the cerium pyrophosphates was carded out by doping titanium. This stabilization is a significant improvement, which enables to apply these amorphous pyrophosphates not only to cosmetics and paints, but also plastics and films.展开更多
Uniform CeVO4 nanowires with diameter of about 25 nm were synthesized by the water-in-oil microemulsion method at room temperature from cerous chloride, sodium orthophosphate, sodium chloride, cyclohexane, Triton X-10...Uniform CeVO4 nanowires with diameter of about 25 nm were synthesized by the water-in-oil microemulsion method at room temperature from cerous chloride, sodium orthophosphate, sodium chloride, cyclohexane, Triton X-100 and cetyltrimethyl ammonium bromide (CTAB). The crystal structure and morphology of the nanowires were characterized by XRD and TEM, respectively. The UV-vis absorption was detected by UV-vis spectrophotometer techniques. The results showed that as-prepared nanowires with the hexagonal phase have obvious quantum confinement effect and semiconductor characteristics. Little sodium chloride could play a positive role on the formation of CePO4 nanowires at room temperature. The size of the nanowires can be controlled through the joining of sodium chloride. C 2009 Yi Bin Yin. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
ZnS nanoparticles were prepared by using solid-state reaction method at room temperature in agate mortar for the first time. The average particle size was about 20nm. This reaction is affected by the structure of reac...ZnS nanoparticles were prepared by using solid-state reaction method at room temperature in agate mortar for the first time. The average particle size was about 20nm. This reaction is affected by the structure of reactant, crystal water and defects.展开更多
This report describes triethylammonium acetate (TEAA) ionic liquid catalyzed one pot synthesis of 6-amino-4-aryl-5-cyano-3- methyl-1-phenyl-1,4-dihydropyrano [2,3-c]pyrazoles by the reaction of aromatic aldehyde, ma...This report describes triethylammonium acetate (TEAA) ionic liquid catalyzed one pot synthesis of 6-amino-4-aryl-5-cyano-3- methyl-1-phenyl-1,4-dihydropyrano [2,3-c]pyrazoles by the reaction of aromatic aldehyde, malononitrile and 3-methyl-1-phenyl-2- pyrazolin-5-one at room temperature. TEAA plays dual role as reaction media and catalyst. It can also be easily recovered and reused in several runs. TEAA provides greener reaction protocol to present methodology which obviates the need of organic solvents, expensive and toxic catalyst.展开更多
Two kinds of new room temperature ionic liquids (RTILs), 1-allyl-3-methylimidazolium chloride (AMIMCl) and 1-butyl-3-methylimidazolium chloride (BMIMCl), were synthesized and used for the dissolution of konjac g...Two kinds of new room temperature ionic liquids (RTILs), 1-allyl-3-methylimidazolium chloride (AMIMCl) and 1-butyl-3-methylimidazolium chloride (BMIMCl), were synthesized and used for the dissolution of konjac glucomannan (KGM). The experimental results showed that the solubility of KGM in AMIMCl was better than that in BMIMCl. Regenerated KGM were obtained by adding anhydrous alcohol to the KGM / ionic liquids solutions. Solubility, molecular weight, structure, and thermal property of the regenerated KGM were investigated by polarized optical microscopy (POM), viscosimetry, infrared spectroscopy (IR), X-ray diffraction technique (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). It was demonstrated that the viscosity-averaged molecular weight of the KGM samples decreased after regeneration because of the molecular degradation of KGM. Results from IR and XRD indicated that the chemical structure and the crystalline form of regenerated KGM were not changed. Results from TG and DSC showed that the thermal stability of the regenerated KGM samples only slightly decreased. These results suggest that AMIMCl and BMIMCl are direct and effective solvents for KGM.展开更多
Here we demonstrate a room-temperature drop-coating method for MAPbI_(3) films.By using low-boiling-point solvent,high-quality MAPbI_(3) films were made by simply casting a drop of solution onto the substrate at room ...Here we demonstrate a room-temperature drop-coating method for MAPbI_(3) films.By using low-boiling-point solvent,high-quality MAPbI_(3) films were made by simply casting a drop of solution onto the substrate at room temperature.This approach took advantage of the synergistic effect of good wettability and volatility of the solvent,enabling high nuclei density and compact film at room temperature.The crystal growth in different solvents was in-situ observed by using optical microscope,which helped us to understand the mechanism for the formation of different film morphology.Perovskite solar cells gave a PCE of 18.21%.展开更多
Conducted in the ionic liquids, activated and inactivated halides, acyl chlorides, tosylate, and bezotriazolyl acylates were converted to corresponding azide and thiocyanide compounds in high yields under mild conditi...Conducted in the ionic liquids, activated and inactivated halides, acyl chlorides, tosylate, and bezotriazolyl acylates were converted to corresponding azide and thiocyanide compounds in high yields under mild conditions.展开更多
The in situ synthesized MoSi2-SiC composite is proved to be of higher fracture toughness than the monolithic MoSi2. The TEM and HREM study reveals that the interface between MoSi2/SiC is of direct atomic bonding witho...The in situ synthesized MoSi2-SiC composite is proved to be of higher fracture toughness than the monolithic MoSi2. The TEM and HREM study reveals that the interface between MoSi2/SiC is of direct atomic bonding without any amorphous glassy phase, such the SiO2 structure. Based on the fractography and the observation of crack propagation path from indentation, it is concluded that the toughening of such composite at room temperature can be attributed to the high interfacial binding energy, the refinement of the MoSi2 matrix and the deflection and bridging behavior in the crack propagation.展开更多
Rechargeable lithium/sodium-sulfur batteries working at room temperature(RT-Li/S,RT-Na/S)appear to be a promising energy storage system in terms of high theoretical energy density,low cost,and abundant resources in na...Rechargeable lithium/sodium-sulfur batteries working at room temperature(RT-Li/S,RT-Na/S)appear to be a promising energy storage system in terms of high theoretical energy density,low cost,and abundant resources in nature.They are,thus,considered as highly attractive candidates for future application in energy storage devices.Nevertheless,the solubility of sulfur species,sluggish kinetics of lithium/sodium sulfide compounds,and high reactivity of metallic anodes render these cells unstable.As a consequence,metal-sulfur batteries present low reversible capacity and quick capacity loss,which hinder their practical application.Investigations to address these issues regarding S cathodes are critical to the increase of their performance and our fundamental understanding of RT-Li/S and RT-Na/S battery systems.Metal-sulfur interactions,recently,have attracted considerable attention,and there have been new insights on pathways to high‐performance RT-Li/Na sulfur batteries,due to the following factors:(1)deliberate construction of metal-sulfur interactions can enable a leap in capacity;(2)metal-sulfur interactions can confine S species,as well as sodium sulfide compounds,to stop shuttle effects;(3)traces of metal species can help to encapsulate a high loading mass of sulfur with high‐cost efficiency;and(4)metal components make electrodes more conductive.In this review,we highlight the latest progress in sulfide immobilization via constructing metal bonding between various metals and S cathodes.Also,we summarize the storage mechanisms of Li/Na as well as the metal-sulfur interaction mechanisms.Furthermore,the current challenges and future remedies in terms of intact confinement and optimization of the electrochemical performance of RT-Li/Na sulfur systems are discussed in this review.展开更多
Mesoporous zinc oxide nanostructures are successfully synthesized via the sol-gel route by using a rice husk as the template for ethanol sensing at room temperature. The structure and morphology of the nanostructures ...Mesoporous zinc oxide nanostructures are successfully synthesized via the sol-gel route by using a rice husk as the template for ethanol sensing at room temperature. The structure and morphology of the nanostructures are characterized by x-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption-desorption analyses. The mechanism for the growth of zinc oxide nanostructures over the biotemplate is proposed. SEM and TEM observations also reveal the formation of spherical zinc oxide nanoparticles over the interwoven fibrous network. Multiple sized pores having pore diameter ranging from 10- 4Ohm is also evidenced from the pore size distribution plot. The larger surface area and porous nature of the material lead to high sensitivity (40.93% for 300 ppm of ethanol), quick response (42s) and recovery (40 s) towards ethanol at 30014. The porous nature of the interwoven fibre-like network affords mass transportation of ethanol vapor, which results in faster surface accessibility, and hence it acts as a potential candidate for ethanol sensing at room temperature.展开更多
All-solid-state(ASS)Na-S batteries are promising for large-scale energy storage because of the incombustible solid electrolyte and avoiding the dissolution of intermediates.However,the poor contact between the active ...All-solid-state(ASS)Na-S batteries are promising for large-scale energy storage because of the incombustible solid electrolyte and avoiding the dissolution of intermediates.However,the poor contact between the active material and the solid electrolyte in the positive electrode leads to poor electrochemical performance.Here,we report an aqueous solution approach to fabricate Na3SbS4-coated SexS-based active materials for a Na-S battery working at room temperature.Compared with the Na3SbS4 and SexS mixed cathode,the coated cathode achieves significantly improved Na-ion diffusion kinetics and reduced impedance resistance.Additionally,the nanoparticle coating sustains the volume expansion of the cathode during cycling.The resulting batteries deliver an intensively enhanced specific capacity at various rates.Regardless of the mass loading,the Na3SbS4-coated cathode maintains a decent reversible capacity for the long-term discharge/charge cycling.The best battery achieves an initial discharge capacity of509 mAh g^-1 at a current density of 437.4 mA g^-1 and capacity retention of 98.9%for 100 cycles.To the best of our knowledge,this is one of the best room temperature ASS Na-S battery so far.This work demonstrates that Na3SbS4 is very promising for the cathode coating purpose for ASS Na-S batteries.展开更多
Well-aligned and closely-packed silicon nanopillar (SNP) arrays are fabricated by using a simple method with magnetron sputtering of Si on a porous anodic alumina (PAA) template at room temperature. The SNPs are f...Well-aligned and closely-packed silicon nanopillar (SNP) arrays are fabricated by using a simple method with magnetron sputtering of Si on a porous anodic alumina (PAA) template at room temperature. The SNPs are formed by selective growth on the top of the PAA pore walls. The growth mechanism analysis indicates that the structure of the SNPs can be modulated by the pore spacing of the PAA and the sputtering process and is independent of the wall width of the PAA. Moreover, nanocrystals are identified by using transmission electron microscopy in the as-deposited SNP samples, which are related to the heat isolation structure of the SNPs. The Raman focus depth profile reveals a high crystallization ratio on the surface.展开更多
In this paper,ultra-long and large-scaled ZnO microwire arrays are grown by the chemical vapor deposition method,and a single ZnO microwire-based non-balanced electric bridge ethanol gas sensor is fabricated.The exper...In this paper,ultra-long and large-scaled ZnO microwire arrays are grown by the chemical vapor deposition method,and a single ZnO microwire-based non-balanced electric bridge ethanol gas sensor is fabricated.The experimental results show that the gas sensor has good repeatability,high response rate,short response,and recovery time at room temperature(25℃).The response rate of the gas sensor exposed to 90-ppm ethanol is about 93%,with a response time and recovery time are 0.3 s and 0.7 s respectively.As a contrast,the traditional resistive gas sensor of a single ZnO microwire shows very small gas response rate.Therefore,ethanol gas sensor based on non-balanced electric bridge can obviously enhance gas sensing characteristics,which provides a feasible method of developing the high performance ZnO-based gas sensor.展开更多
Two-dimensional(2D)thermoelectric(TE)materials have been widely developed;however,some 2D materials exhibit isotropic phonon,electron transport properties,and poor TE performance,which limit their application scope.Th...Two-dimensional(2D)thermoelectric(TE)materials have been widely developed;however,some 2D materials exhibit isotropic phonon,electron transport properties,and poor TE performance,which limit their application scope.Thus,exploring excellent anisotropic and ultrahigh-performance TE materials are very warranted.Herein,we first investigate the phonon thermal and TE properties of a novel 2D-connectivity ternary compound named Ga2I2S2.This paper comprehensively studies the phonon dispersion,phonon anharmonicity,lattice thermal conductivity,electronic structure,carrier mobility,Seebeck coefficient,electrical conductivity,and the dimensionless figure of merit(ZT)versus carrier concentration for 2D Ga_(2)I_(2)S_(2).We conclude that the in-plane lattice thermal conductivities of Ga_(2)I_(2)S_(2) at room temperature(300 K)are found to be 1.55 W mK^(−1) in the X-axis direction(xx-direction)and 3.82 W mK^(−1)in the Y-axis direction(yy-direction),which means its anisotropy ratio reaches 1.46.Simultaneously,the TE performance of p-type and n-type doping 2D Ga2I2S2 also shows significant anisotropy,giving rise to the ZT peak values of p-type doping in xx-and yy-directions being 0.81 and 1.99,respectively,and those of n-type doping reach ultrahigh values of 7.12 and 2.89 at 300 K,which are obviously higher than the reported values for p-type and n-type doping ternary compound Sn2BiX(ZT∼1.70 and∼2.45 at 300 K)(2020 Nano Energy 67104283).This work demonstrates that 2D Ga_(2)I_(2)S_(2) has high anisotropic TE conversion efficiency and can also be used as a new potential room-temperature TE material.展开更多
SnO2-ln2O3 hierarchical microspheres were prepared by the hydrothermal and solvothermal method. The morphology, phase crystallinity of the obtained SnO2-In203 were measured by X-ray diffraetion(XRD), scan electron m...SnO2-ln2O3 hierarchical microspheres were prepared by the hydrothermal and solvothermal method. The morphology, phase crystallinity of the obtained SnO2-In203 were measured by X-ray diffraetion(XRD), scan electron microscopy(SEM), respectively. A room temperature ozone sensor based on SnO2-In2O3 hierarchical microspheres was fabricated and investigated. The gas sensing properties of the sensor using SnO2-In2O3 strongly depended on the proportion of SnO2 and In2O3. The sensitivity and response/recovery speed were greatly enhanced by UV illumination. A gas sensing mechanism related to oxygen defect was suggested.展开更多
Room temperature sodium–sulfur(RT Na-S)battery with high theoretical energy density and low cost has spurred tremendous interest,which is recognized as an ideal candidate for large-scale energy storage applications.H...Room temperature sodium–sulfur(RT Na-S)battery with high theoretical energy density and low cost has spurred tremendous interest,which is recognized as an ideal candidate for large-scale energy storage applications.However,serious sodium polysulfide shutting and sluggish reaction kinetics lead to rapid capacity decay and poor Coulombic efficiency.Recently,catalytic materials capable of adsorbing and catalyzing the conversion of polysulfides are profiled as a promising method to improve electrochemical performance.In this review,the research progress is summarized that the application of catalytic materials in RT Na-S battery.For the role of catalyst on the conversion of sulfur species,specific attention is focused on the influence factors of reaction rate during different redox processes.Various catalytic materials based on lightweight and high conductive carbon materials,including heteroatom-doped carbon,metals and metal compounds,single-atom and heterostructure,promote the reaction kinetic via lowered energy barrier and accelerated charge transfer.Additionally,the adsorption capacity of the catalytic materials is the key to the catalytic effect.Particular attention to the interaction between polysulfides and sulfur host materials is necessary for the exploration of catalytic mechanism.Lastly,the challenges and outlooks toward the desired design of efficient catalytic materials for RT Na-S battery are discussed.展开更多
基金the Natural Science Foundation of Shandong Province, China (Grant No. ZR2019MA041)the Taishan Scholar Project of Shandong Province, China (Grant No. ts20190939)+1 种基金the National Natural Science Foundation of China (Grant No. 62071200)the Shandong Provincial Natural Science Foundation, China (Grant No. ZR2020QA052)。
文摘The quantum anomalous Hall(QAH) effect has attracted enormous attention since it can induce topologically protected conducting edge states in an intrinsic insulating material. For practical quantum applications, the main obstacle is the non-existent room temperature QAH systems, especially with both large topological band gap and robust ferromagnetic order. Here, according to first-principles calculations, we predict the realization of the room temperature QAH effect in a two-dimensional(2D) honeycomb lattice, RuCS_(3) with a non-zero Chern number of C = 1. Especially, the nontrivial topology band gap reaches up to 336 me V for RuCS_(3). Moreover, we find that RuCS_(3) has a large magnetic anisotropy energy(2.065 me V) and high Curie temperature(696 K). We further find that the non-trivial topological properties are robust against the biaxial strain. The robust topological and magnetic properties make RuCS_(3) have great applications in room temperature spintronics and nanoelectronics.
基金The authors acknowledge the Project supported by the National Key R&D Program of China(2019YFE0103600,2018YFB1502101)the Key R&D Program of Shandong Province,China(2020CXGC010402)+4 种基金the National Natural Science Foundation of China(51801197)the Liaoning Revitalization Talents Program(XLYC2002076)the Dalian High-level Talents Program(2019RD09)the Youth Innovation Promotion Association CAS(2019189)K.C.Wong Education Foundation(GJTD-2018–06).
文摘This paper presents the catalytic effect of NaH doped nanocrystalline TiO_(2)(designated as NaTiOxH)in the improvement of MgH_(2)hydrogen storage properties.The catalyst preparation involves ball milling NaH with TiO_(2)for 3 hr.The addition of 5 wt%NaTiOxH powder into MgH_(2)reduces its operating temperature to∼185℃,which is∼110℃lower than the additive-free as-milled MgH_(2).The composite remarkably desorbs∼7.2 wt%H_(2)within 15 min at∼290℃and reabsorbs∼4.5 wt%H_(2)in 45 min at room temperature under 50 bar H_(2).MgH_(2)dehydrogenation is activated at 57 kJ/mol by the catalyst.More importantly,the addition of 2.5 wt%NaTiOxH catalyst aids MgH_(2)to reversibly produce∼6.1 wt%H_(2)upon 100 cycles within 475 hr at 300℃.Microstructural investigation into the catalyzed MgH_(2)composite reveals a firm contact existing between NaTiOxH and MgH_(2)particles.Meanwhile,the NaTiOxH catalyst consists of catalytically active Ti_(3)O_(5),and“rod-like”Na_(2)Ti_(3)O_(7)species liberated in-situ during preparation;these active species could provide multiple hydrogen diffusion pathways for an improved MgH_(2)sorption process.Furthermore,the elemental characterization identifies the reduced valence states of titanium(Ti<4+)which show some sort of reversibility consistent with H_(2)insertion and removal.This phenomenon is believed to enhance the mobility of Mg/MgH_(2)electrons by the creation and elimination of oxygen vacancies in the defective(TiO_(2-x))catalyst.Our findings have therefore moved MgH_(2)closer to practical applications.
基金financial support from the Collaborative Education Project of IndustryUniversity Cooperation of the Ministry of Education of China(Grant No.202101256024)the National Natural Science Foundation of China(Grant Nos.11904209 and 61802144)。
文摘A heterojunction structure design is a very good method for improving the properties of semiconductors in many research fields.This method is employed in the present study to promote the gas-sensing performance of Ag_(3)PO_(4)nanocomposites at room temperature(25℃).A nanocomposite of Ag_(3)PO_(4)nanoparticles and three-dimensional peony-like WO_(3)(WO_(3)/Ag_(3)PO_(4))was successfully prepared by the precipitation method.The crystalline phases were analyzed by xray diffraction and the microstructure was characterized by scanning electron microscopy and transmission electron microscopy.The chemical bonding states were analyzed by x-ray photoelectron spectroscopy.The gas-sensing performance of WO_(3)/Ag_(3)PO_(4)sensors was systematically explored at room temperature.The composite sensors possessed a higher response and lower detection limit(1 ppm)to NH_(3)than those made of a single type of material;this is ascribed to the synergistic effect achieved by the heterojunction structure.Among the different composite sensors tested,gas sensor A5W5(Ag_(3)PO_(4):WO3mass ratio of 5:5)displayed the highest response to NH_(3)at room temperature.Interestingly,the A5W5 gas sensor exhibited relatively good stability and excellent selectivity to NH_(3).The A5W5 sensor also displayed a relatively good response under high humidity.The gas-sensing mechanism of the WO_(3)/Ag_(3)PO_(4)sensors is explained in detail.Taken together,the as-prepared sensor is highly efficient at detecting NH_(3)and could be suitable for practical applications.In addition,this study also provides a new method for developing Ag_(3)PO_(4)-based sensors in the gas-sensing field.
文摘1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralone is still a big challenge with low-temperature processes using environmentally friendly routes even after decades of research. Herein, we demonstrate room-temperature oxidation of tetralin to 1-tetralone over layered double hydroxide-hosted sulphonato-salen-nickel(II) complex, LDH-[Ni-salen]. The layered double hydroxide-hosted sulphonato-salen-nickel(II) compound was characterized by powder X-ray diffraction, Fourier transform infrared spectrometer (FTIR), UV-Visible diffuse reflectance spectra, scanning electron microscopy (SEM) and elemental analysis. The theoretical calculations of free sulphonato-salen-nickel(II) complex using Density Functional Theory/CAM-B3LYP at the 6-311++ G(d,p) level of theory were also used to determine the orientation of the Ni-salen compound within the layered structure. The immobilized compound, LDH-[Ni-salen] was found to be an effective reusable catalyst for the oxidation of tetralin to 1-tetralone using a combination of trimethylacetaldehyde and molecular oxygen (14.5 psi) and at 25°C. At 45.5% conversion, tetralin was converted to 1-tetralone with 77.2% selectivity at room temperature and atmospheric pressure after 24 h. The catalyst recycles test and hot filtration experiment showed that oxidation proceeded through Ni(II) sites in LDH-[Ni-salen]. The catalysts were reused several times without losing their catalytic activity and selectivity. The present results may provide a convenient strategy for the preparation of 1-tetralone using layered double hydroxide-based heterogeneous catalyst at ambient temperature for industrial application in near future.
基金supported by the Natural Sci-ence Foundation of Guangxi Province, China (No. 0640009)
文摘Nano-sized cerium-titanium pyrophosphates Ce1-xTixP2O7 (with x = 0, 0.2, 0.5, 0.7, 0.9, and 1.0) were obtained by grinding a mixture of Ce(SO4)2·4H2O, Ti(SO4)2, and Na4P2O7·10H2O in the presence of surfactant PEG-400 at room temperature, washing the mixture with water to remove soluble inorganic salts, and drying at 100℃. The products and their calcined samples were characterized using ultraviolet-visible spectroscopy (UV-vis), thermogravimetry and differential thermal analyses (TG/DTA), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). The results show that nano-sized Ce1-xTixP2O7 behave as an excellent UV-shielding material. Thereinto, the CeP2O7 has the most excellent UV-shielding effect, and the amorphous state of Ce0.8Ti0.2P2O7 can keep at a higher temperature than CeP2O7. Therefore, the stabilization of the amorphous state of the cerium pyrophosphates was carded out by doping titanium. This stabilization is a significant improvement, which enables to apply these amorphous pyrophosphates not only to cosmetics and paints, but also plastics and films.
基金support by the Awarding Foundation for Middle and Young-Age Scientist of Shandong Province(2005).
文摘Uniform CeVO4 nanowires with diameter of about 25 nm were synthesized by the water-in-oil microemulsion method at room temperature from cerous chloride, sodium orthophosphate, sodium chloride, cyclohexane, Triton X-100 and cetyltrimethyl ammonium bromide (CTAB). The crystal structure and morphology of the nanowires were characterized by XRD and TEM, respectively. The UV-vis absorption was detected by UV-vis spectrophotometer techniques. The results showed that as-prepared nanowires with the hexagonal phase have obvious quantum confinement effect and semiconductor characteristics. Little sodium chloride could play a positive role on the formation of CePO4 nanowires at room temperature. The size of the nanowires can be controlled through the joining of sodium chloride. C 2009 Yi Bin Yin. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘ZnS nanoparticles were prepared by using solid-state reaction method at room temperature in agate mortar for the first time. The average particle size was about 20nm. This reaction is affected by the structure of reactant, crystal water and defects.
文摘This report describes triethylammonium acetate (TEAA) ionic liquid catalyzed one pot synthesis of 6-amino-4-aryl-5-cyano-3- methyl-1-phenyl-1,4-dihydropyrano [2,3-c]pyrazoles by the reaction of aromatic aldehyde, malononitrile and 3-methyl-1-phenyl-2- pyrazolin-5-one at room temperature. TEAA plays dual role as reaction media and catalyst. It can also be easily recovered and reused in several runs. TEAA provides greener reaction protocol to present methodology which obviates the need of organic solvents, expensive and toxic catalyst.
基金Funded by the National Natural Scieace Foundation of China(50703031)
文摘Two kinds of new room temperature ionic liquids (RTILs), 1-allyl-3-methylimidazolium chloride (AMIMCl) and 1-butyl-3-methylimidazolium chloride (BMIMCl), were synthesized and used for the dissolution of konjac glucomannan (KGM). The experimental results showed that the solubility of KGM in AMIMCl was better than that in BMIMCl. Regenerated KGM were obtained by adding anhydrous alcohol to the KGM / ionic liquids solutions. Solubility, molecular weight, structure, and thermal property of the regenerated KGM were investigated by polarized optical microscopy (POM), viscosimetry, infrared spectroscopy (IR), X-ray diffraction technique (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). It was demonstrated that the viscosity-averaged molecular weight of the KGM samples decreased after regeneration because of the molecular degradation of KGM. Results from IR and XRD indicated that the chemical structure and the crystalline form of regenerated KGM were not changed. Results from TG and DSC showed that the thermal stability of the regenerated KGM samples only slightly decreased. These results suggest that AMIMCl and BMIMCl are direct and effective solvents for KGM.
基金We thank the National Key Research and Development Program of China(2017YFA0206600)the National Natural Science Foundation of China(51773045,21772030,51922032 and 21961160720)for financial support.
文摘Here we demonstrate a room-temperature drop-coating method for MAPbI_(3) films.By using low-boiling-point solvent,high-quality MAPbI_(3) films were made by simply casting a drop of solution onto the substrate at room temperature.This approach took advantage of the synergistic effect of good wettability and volatility of the solvent,enabling high nuclei density and compact film at room temperature.The crystal growth in different solvents was in-situ observed by using optical microscope,which helped us to understand the mechanism for the formation of different film morphology.Perovskite solar cells gave a PCE of 18.21%.
文摘Conducted in the ionic liquids, activated and inactivated halides, acyl chlorides, tosylate, and bezotriazolyl acylates were converted to corresponding azide and thiocyanide compounds in high yields under mild conditions.
基金the National Natural Science Foundation of China (No. 59895150-04-02).
文摘The in situ synthesized MoSi2-SiC composite is proved to be of higher fracture toughness than the monolithic MoSi2. The TEM and HREM study reveals that the interface between MoSi2/SiC is of direct atomic bonding without any amorphous glassy phase, such the SiO2 structure. Based on the fractography and the observation of crack propagation path from indentation, it is concluded that the toughening of such composite at room temperature can be attributed to the high interfacial binding energy, the refinement of the MoSi2 matrix and the deflection and bridging behavior in the crack propagation.
基金This study was financially supported by the National Natural Science Foundation of China(No.51971124).
文摘Rechargeable lithium/sodium-sulfur batteries working at room temperature(RT-Li/S,RT-Na/S)appear to be a promising energy storage system in terms of high theoretical energy density,low cost,and abundant resources in nature.They are,thus,considered as highly attractive candidates for future application in energy storage devices.Nevertheless,the solubility of sulfur species,sluggish kinetics of lithium/sodium sulfide compounds,and high reactivity of metallic anodes render these cells unstable.As a consequence,metal-sulfur batteries present low reversible capacity and quick capacity loss,which hinder their practical application.Investigations to address these issues regarding S cathodes are critical to the increase of their performance and our fundamental understanding of RT-Li/S and RT-Na/S battery systems.Metal-sulfur interactions,recently,have attracted considerable attention,and there have been new insights on pathways to high‐performance RT-Li/Na sulfur batteries,due to the following factors:(1)deliberate construction of metal-sulfur interactions can enable a leap in capacity;(2)metal-sulfur interactions can confine S species,as well as sodium sulfide compounds,to stop shuttle effects;(3)traces of metal species can help to encapsulate a high loading mass of sulfur with high‐cost efficiency;and(4)metal components make electrodes more conductive.In this review,we highlight the latest progress in sulfide immobilization via constructing metal bonding between various metals and S cathodes.Also,we summarize the storage mechanisms of Li/Na as well as the metal-sulfur interaction mechanisms.Furthermore,the current challenges and future remedies in terms of intact confinement and optimization of the electrochemical performance of RT-Li/Na sulfur systems are discussed in this review.
文摘Mesoporous zinc oxide nanostructures are successfully synthesized via the sol-gel route by using a rice husk as the template for ethanol sensing at room temperature. The structure and morphology of the nanostructures are characterized by x-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption-desorption analyses. The mechanism for the growth of zinc oxide nanostructures over the biotemplate is proposed. SEM and TEM observations also reveal the formation of spherical zinc oxide nanoparticles over the interwoven fibrous network. Multiple sized pores having pore diameter ranging from 10- 4Ohm is also evidenced from the pore size distribution plot. The larger surface area and porous nature of the material lead to high sensitivity (40.93% for 300 ppm of ethanol), quick response (42s) and recovery (40 s) towards ethanol at 30014. The porous nature of the interwoven fibre-like network affords mass transportation of ethanol vapor, which results in faster surface accessibility, and hence it acts as a potential candidate for ethanol sensing at room temperature.
基金supported by the National Key R&D Program of China(grant no.2018YFB0104300)the Natural Science Foundation of Hebei Province(E2018203301)。
文摘All-solid-state(ASS)Na-S batteries are promising for large-scale energy storage because of the incombustible solid electrolyte and avoiding the dissolution of intermediates.However,the poor contact between the active material and the solid electrolyte in the positive electrode leads to poor electrochemical performance.Here,we report an aqueous solution approach to fabricate Na3SbS4-coated SexS-based active materials for a Na-S battery working at room temperature.Compared with the Na3SbS4 and SexS mixed cathode,the coated cathode achieves significantly improved Na-ion diffusion kinetics and reduced impedance resistance.Additionally,the nanoparticle coating sustains the volume expansion of the cathode during cycling.The resulting batteries deliver an intensively enhanced specific capacity at various rates.Regardless of the mass loading,the Na3SbS4-coated cathode maintains a decent reversible capacity for the long-term discharge/charge cycling.The best battery achieves an initial discharge capacity of509 mAh g^-1 at a current density of 437.4 mA g^-1 and capacity retention of 98.9%for 100 cycles.To the best of our knowledge,this is one of the best room temperature ASS Na-S battery so far.This work demonstrates that Na3SbS4 is very promising for the cathode coating purpose for ASS Na-S batteries.
基金supported by the Major State Basic Research Programme of China(Grant No.2007CB613404)the National Natural Science Foundation of China(Grant Nos.60906035,61036001,61036003,and 51072194)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.ISCAS2009T01)
文摘Well-aligned and closely-packed silicon nanopillar (SNP) arrays are fabricated by using a simple method with magnetron sputtering of Si on a porous anodic alumina (PAA) template at room temperature. The SNPs are formed by selective growth on the top of the PAA pore walls. The growth mechanism analysis indicates that the structure of the SNPs can be modulated by the pore spacing of the PAA and the sputtering process and is independent of the wall width of the PAA. Moreover, nanocrystals are identified by using transmission electron microscopy in the as-deposited SNP samples, which are related to the heat isolation structure of the SNPs. The Raman focus depth profile reveals a high crystallization ratio on the surface.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61574026 and 11405017)the Liaoning Provincial Natural Science Foundation,China(Grant No.201602453)
文摘In this paper,ultra-long and large-scaled ZnO microwire arrays are grown by the chemical vapor deposition method,and a single ZnO microwire-based non-balanced electric bridge ethanol gas sensor is fabricated.The experimental results show that the gas sensor has good repeatability,high response rate,short response,and recovery time at room temperature(25℃).The response rate of the gas sensor exposed to 90-ppm ethanol is about 93%,with a response time and recovery time are 0.3 s and 0.7 s respectively.As a contrast,the traditional resistive gas sensor of a single ZnO microwire shows very small gas response rate.Therefore,ethanol gas sensor based on non-balanced electric bridge can obviously enhance gas sensing characteristics,which provides a feasible method of developing the high performance ZnO-based gas sensor.
基金support from the National Natural Science Foundation of China[51720105007,52076031,11602149,51806031,52176166]the Fundamental Research Funds for the Central Universities[DUT19RC(3)006]the computing resources from the Supercomputer Center of Dalian University of Technology and RWTH Aachen University under project 3357.
文摘Two-dimensional(2D)thermoelectric(TE)materials have been widely developed;however,some 2D materials exhibit isotropic phonon,electron transport properties,and poor TE performance,which limit their application scope.Thus,exploring excellent anisotropic and ultrahigh-performance TE materials are very warranted.Herein,we first investigate the phonon thermal and TE properties of a novel 2D-connectivity ternary compound named Ga2I2S2.This paper comprehensively studies the phonon dispersion,phonon anharmonicity,lattice thermal conductivity,electronic structure,carrier mobility,Seebeck coefficient,electrical conductivity,and the dimensionless figure of merit(ZT)versus carrier concentration for 2D Ga_(2)I_(2)S_(2).We conclude that the in-plane lattice thermal conductivities of Ga_(2)I_(2)S_(2) at room temperature(300 K)are found to be 1.55 W mK^(−1) in the X-axis direction(xx-direction)and 3.82 W mK^(−1)in the Y-axis direction(yy-direction),which means its anisotropy ratio reaches 1.46.Simultaneously,the TE performance of p-type and n-type doping 2D Ga2I2S2 also shows significant anisotropy,giving rise to the ZT peak values of p-type doping in xx-and yy-directions being 0.81 and 1.99,respectively,and those of n-type doping reach ultrahigh values of 7.12 and 2.89 at 300 K,which are obviously higher than the reported values for p-type and n-type doping ternary compound Sn2BiX(ZT∼1.70 and∼2.45 at 300 K)(2020 Nano Energy 67104283).This work demonstrates that 2D Ga_(2)I_(2)S_(2) has high anisotropic TE conversion efficiency and can also be used as a new potential room-temperature TE material.
基金Supported by the National Natural Science Foundation of China(Nos.60906036,61074172,61134010)the Program for Changjiang Scholars and Innovative Research Team in Universities of China(No.IRT1017)
文摘SnO2-ln2O3 hierarchical microspheres were prepared by the hydrothermal and solvothermal method. The morphology, phase crystallinity of the obtained SnO2-In203 were measured by X-ray diffraetion(XRD), scan electron microscopy(SEM), respectively. A room temperature ozone sensor based on SnO2-In2O3 hierarchical microspheres was fabricated and investigated. The gas sensing properties of the sensor using SnO2-In2O3 strongly depended on the proportion of SnO2 and In2O3. The sensitivity and response/recovery speed were greatly enhanced by UV illumination. A gas sensing mechanism related to oxygen defect was suggested.
基金financial support from National Natural Science Foundation of China(Nos.52020105010,51972313,51927803,52072378,51902316 and 51525206)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA22010602)+2 种基金LiaoNing Revitalization Talents Program(No.XLYC1908015)Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.Y201942)the Special Projects of the Central Government in Guidance of Local Science and Technology Development(No.2020JH6/10500024)。
文摘Room temperature sodium–sulfur(RT Na-S)battery with high theoretical energy density and low cost has spurred tremendous interest,which is recognized as an ideal candidate for large-scale energy storage applications.However,serious sodium polysulfide shutting and sluggish reaction kinetics lead to rapid capacity decay and poor Coulombic efficiency.Recently,catalytic materials capable of adsorbing and catalyzing the conversion of polysulfides are profiled as a promising method to improve electrochemical performance.In this review,the research progress is summarized that the application of catalytic materials in RT Na-S battery.For the role of catalyst on the conversion of sulfur species,specific attention is focused on the influence factors of reaction rate during different redox processes.Various catalytic materials based on lightweight and high conductive carbon materials,including heteroatom-doped carbon,metals and metal compounds,single-atom and heterostructure,promote the reaction kinetic via lowered energy barrier and accelerated charge transfer.Additionally,the adsorption capacity of the catalytic materials is the key to the catalytic effect.Particular attention to the interaction between polysulfides and sulfur host materials is necessary for the exploration of catalytic mechanism.Lastly,the challenges and outlooks toward the desired design of efficient catalytic materials for RT Na-S battery are discussed.