The H+H2 reaction is the simplest chemical reaction system and has long been the prototype model in the study of reaction dynamics. Here we report a high resolution experimental investigation of the state-to-state rea...The H+H2 reaction is the simplest chemical reaction system and has long been the prototype model in the study of reaction dynamics. Here we report a high resolution experimental investigation of the state-to-state reaction dynamics in the H+HD→H2+D reaction by using the crossed molecular beams method and velocity map ion imaging technique at the collision energy of 1.17 eV. D atom products in this reaction were probed by the near threshold 1+1'(vacuum ultraviolet+ultraviolet) laser ionization scheme. The ion image with both high angular and energy resolution were acquired. State-to-state differential cross sections was accurately derived. Fast forward scattering oscillations, relating with interference effects in the scattering process, were clearly observed for H2 products at H2(v'=0,j'=1) and H2(v'=0,j'=3) rovibrational levels. This study further demonstrates the importance of measuring high-resolution differential cross sections in the study of state-to-state reaction dynamics in the gas phase.展开更多
The direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol has attracted much attention as an environmentally benign and alternative route for conventional routes.Herein,a series of cerium oxide catalysts ...The direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol has attracted much attention as an environmentally benign and alternative route for conventional routes.Herein,a series of cerium oxide catalysts with various textural features and surface properties were prepared by the one-pot synthesis method for the direct DMC synthesis from CO_(2)and methanol,and the structure-performance relationship was investigated in detail.Characterization results revealed that both of surface acid-base properties and the oxygen vacancies contents decreased with the rising crystallinity at increasingly higher calcination temperature accompanied by an unexpectedly volcano-shaped trend of DMC yield observed on the catalysts.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)studies indicated that the adsorption rate of methanol is slower than that of CO_(2)and the methanol activation state largely influences the formation of key intermediate.Although the enhanced surface acidity-basicity and oxygen vacancies brought by low-temperature calcination could facilitate the activation of CO_(2),the presence of excess strongly basic sites on low-crystallinity sample was detrimental to DMC synthesis due to the preferred formation of unreactive mono/polydentate carbonates as well as the further impediment of methanol activation.Moreover,with the use of 2-cyanopyridine as a dehydration reagent,the DMC synthesis was found to be both influenced by the promotion from the rapid in situ removal of water and the inhibition from the competitive adsorption of hydration products on the same active sites.展开更多
The Advanced Glycation End Products(AGE)binding with its receptor can increase reactive oxygen species(ROS)generation through specific signaling mediators.The effect of superoxide(O2-)and O2-mediated ROS and reactive ...The Advanced Glycation End Products(AGE)binding with its receptor can increase reactive oxygen species(ROS)generation through specific signaling mediators.The effect of superoxide(O2-)and O2-mediated ROS and reactive nitrogen species depends on their concentration and location of formation.Nitric oxide(NO)has anti-inflammatory and anticoagulant properties and a vasodilation effect,but NO can be deactivated by reacting with O_(2)^(-).This reaction between NO and O2-produces the potent oxidant ONOO−.Therefore,ONOO-'s regulatory role in AGEs in diabetic cardiovascular complications must considered as a regulator of cardiovascular complications in diabetes.展开更多
N-ethylpyrrole is one of ethylsubstituted derivatives of pyrrole and its excited-state decay dynamics has never been explored.In this work,we investigate ultrafast decay dynamics of N-ethylpyrrole excited to the S_(1)...N-ethylpyrrole is one of ethylsubstituted derivatives of pyrrole and its excited-state decay dynamics has never been explored.In this work,we investigate ultrafast decay dynamics of N-ethylpyrrole excited to the S_(1)electronic state using a femtosecond time-resolved photoelectron imaging method.Two pump wavelengths of 241.9 and 237.7 nm are employed.At 241.9 nm,three time constants,5.0±0.7 ps,66.4±15.6 ps and 1.3±0.1 ns,are derived.For 237.7 nm,two time constants of 2.1±0.1 ps and 13.1±1.2 ps are derived.We assign all these time constants to be associated with different vibrational states in the S_(1)state.The possible decay mechanisms of different S_(1)vibrational states are briefly discussed.展开更多
Excited-state double proton transfer(ESDPT)is a controversial issue which has long been plagued with theoretical and experimental communities.Herein,we took 1,8-dihydroxy-2-naphthaldehyde(DHNA)as a prototype and used ...Excited-state double proton transfer(ESDPT)is a controversial issue which has long been plagued with theoretical and experimental communities.Herein,we took 1,8-dihydroxy-2-naphthaldehyde(DHNA)as a prototype and used combined complete active space selfconsistent field(CASSCF)and multi-state complete active-space second-order perturbation(MS-CASPT2)methods to investigate ESDPT and excited-state deactivation pathways of DHNA.Three different tautomer minima of S1-ENOL,S1-KETO-1,and S1-KETO-2 and two crucial conical intersections of S1 S0-KETO-1 and S1 S0-KETO-2 in and between the S0 and S1 states were obtained.S1-KETO-1 and S1-KETO-2 should take responsibility for experimentally observing dual-emission bands.In addition,two-dimensional potential energy surfaces(2 D-PESs)and linear interpolated internal coordinate paths connecting relevant structures were calculated at the MS-CASPT2//CASSCF level and confirmed a stepwise ESDPT mechanism.Specifically,the first proton transfer from S1-ENOL to S1-KETO-1 is barrierless,whereas the second one from S1-KETO-1 to S1-KETO-2 demands a barrier of ca.6.0 kcal/mol.The linear interpolated internal coordinate path connecting S1-KETO-1(S1-KETO-2)and S_(1) S0-KETO-1(S1 S0-KETO-2)is uphill with a barrier of ca.12.0 kcal/mol,which will trap DHNA in the S_(1) state while therefore enabling dual-emission bands.On the other hand,the S1/S0 conical intersections would also prompt the S_(1) system to decay to the S_(0) state,which could be to certain extent suppressed by locking the rotation of the C5-C8-C9-O10 dihedral angle.These mechanistic insights are not only helpful for understanding ESDPT but also useful for designing novel molecular materials with excellent photoluminescent performances.展开更多
We presented an experimental apparatus combining the H-atom Rydberg tagging time-of-flight technique and the laser detonation source for studying crossed beam reactions at hyperthermal collision energies. The prelimin...We presented an experimental apparatus combining the H-atom Rydberg tagging time-of-flight technique and the laser detonation source for studying crossed beam reactions at hyperthermal collision energies. The preliminary study of the F+D2→DF+D reaction at hyperthermal collision energy of 23.84 kJ/mol was performed. Two beam sources were used in this study: one is the hyperthermal F beam source produced by a laser detonation process, and the other is D2 beam source generated by liquid-N2 cooled pulsed valve. Vibrational state-resolved di erential cross sections (DCSs) of product for the title reaction were determined. From the product vibrational state-resolved DCS, it can be concluded that products DF(v'=0, 1, 2, 3) are predominantly distributed in the sideway and backward scattering directions at this collision energy. However, the highest vibrational excited product DF(v'=4), is clearly peaked in the forward direction. The probable dynamical origins for these forward scattering products were analyzed and discussed.展开更多
We classify condensable𝐸E_(2)-algebras in a modular tensor category C up to 2-Morita equivalence.Physically,this classification provides an explicit criterion to determine when distinct condensable𝐸E_(...We classify condensable𝐸E_(2)-algebras in a modular tensor category C up to 2-Morita equivalence.Physically,this classification provides an explicit criterion to determine when distinct condensable𝐸E_(2)-algebras yield the same condensed topological phase under a two-dimensional anyon condensation process.The relations between different condensable algebras can be translated into their module categories,interpreted physically as gapped domain walls in topological orders.As concrete examples,we interpret the categories of quantum doubles of finite groups and examples beyond group symmetries.Our framework fully elucidates the interplay among condensable𝐸E_(1)-algebras in C,condensable𝐸E_(2)-algebras in C up to 2-Morita equivalence,and Lagrangian algebras in C⊠C.展开更多
The electrochemical biomass valorization of industrial by-products or pollutants using renewable electricity offers significant promise for carbon neutrality.However,the huge challenges still exist in the development ...The electrochemical biomass valorization of industrial by-products or pollutants using renewable electricity offers significant promise for carbon neutrality.However,the huge challenges still exist in the development of efficient bifunctional electrocatalysts.Herein,we put forward a high-efficiency coelectrolysis system by coupling the nitrite reduction reaction(NO_(2)RR)and the glycerol oxidation reaction(GOR)over a novel heterogeneous β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl catalyst.Theβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl shows excellent bifunctional performance with high Faradaic efficiencies of formate(90.1%)and NH_(3)(91.9%)at cell voltage of 1.5 V,high yield rate of formate(89.6 mg h^(-1)cm^(-2))and NH_(3)(36.07 mg h^(-1)cm^(-2))at cell voltage of 1.9 V,and superior stability in an anion exchange membrane co-electrolyzer.The in-situ Raman result confirms the unique Co/Cu-based bimetallic synergistic sites of β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl towards superior GOR performance,while the operando Fourier transform infrared spectroscopy demonstrates the improved protonation kinetics of key intermediates and optimized water dissociation ability ofβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl for high NO_(2)RR activity.Our work illuminates alternative avenues to exploit the innovative and energy-saving technology for the co-production of high-added chemicals.展开更多
Developing energy-efficient nitrite-to-ammonia(NO_(2)RR)conversion technologies while simultaneously enabling the electrochemical upcycling of waste polyethylene terephthalate(PET)plastics into highvalue-added chemica...Developing energy-efficient nitrite-to-ammonia(NO_(2)RR)conversion technologies while simultaneously enabling the electrochemical upcycling of waste polyethylene terephthalate(PET)plastics into highvalue-added chemicals is of great significance.Herein,an atomic oxygen vacancy(V_(o))engineering is developed to optimize the catalytic performance of V_(o2)-Co(OH)F nanoarray towards the NO_(2)RR and PET-derived ethylene glycol oxidation reaction(EGOR).The optimal V_(o2)-Co(OH)F achieves an ultralow operating potential of -0.03 V vs.RHE at -100 mA cm^(-2)and a remarkable NH_(3)Faradaic efficiency(FE)of 98.4% at -0.2 V vs.RHE for NO_(2)RR,and a high formate FE of 98.03% for EGOR.Operando spectroscopic analysis and theoretical calculations revealed that oxygen vacancies play a crucial role in optimizing the electronic structure of V_(o2)-Co(OH)F,modulating the adsorption free energies of key reaction intermediates,and lowering the reaction energy barrier,thereby enhancing its overall catalytic performance.Remarkably,the V_(o2)-Co(OH)F-based NO_(2)RR||EGOR electrolyzer realized high NH_(3)and formate yield rates of 33.9 and 44.9 mg h^(-1)cm^(-2)at 1.7 V,respectively,while demonstrating outstanding long-term stability over 100 h.This work provides valuable insights into the rational design of advanced electrocatalysts for co-electrolysis systems.展开更多
A combination of hard(SiCP)and soft(fly ash)particulate reinforcements could be a strategy to enhance combination of multiple properties of Magnesium and its alloys which otherwise suffer from low stiffness,low wear r...A combination of hard(SiCP)and soft(fly ash)particulate reinforcements could be a strategy to enhance combination of multiple properties of Magnesium and its alloys which otherwise suffer from low stiffness,low wear resistance,and many other critical properties.However,at present a comprehensive and robust map correlating different properties in particle-reinforced composites is much lacking.In this work,an industrial grade AZ91 magnesium alloy reinforced with hard SiC and soft fly ash particles(with 3 vol.%each),has been prepared using stir casting followed by hot extrusion at 325℃with a ratio of 21.5.Microstructure of the hybrid composite was characterized using optical and scanning electron microscopes.The composite exhibited a reduction in average grain size from 13.6 to 7.1μm,concomitantly an increase in Vickers hardness from 73 to 111 HV.The tension-compression yield asymmetry ratios of the unreinforced alloy and hybrid composite were 1.165 and 0.976,respectively indicating higher yield strength for the composite under compressive load.The composite exhibited 76%improvement in damping capacity under time sweep mode,and 28%improvement at 423 K under temperature sweep mode.The tribological characteristics of the composite under dry sliding conditions at sliding speeds and loads in the range of 0.5 to 1.5 m s^(-1)and 10 to 30 N,respectively showed higher wear resistance than the unreinforced alloy.The composite showed 23%improvement in sliding wear resistance at a load of 20 N and a speed of 1 m s^(-1).Finally,efforts have been made to understand the influence of one property on the other by developing statistical property correlation maps from the properties obtained in this study and from the literature.These maps are expected to help in the design of hybrid Metal Matrix Composites for a variety of targeted applications in different sectors.展开更多
Fischer-Tropsch synthesis(FTS)and hydroformylation are pivotal chemical processes for converting syngas and olefins into valuable hydrocarbons and chemicals.Recent advancements in catalyst design,reaction mechanisms,a...Fischer-Tropsch synthesis(FTS)and hydroformylation are pivotal chemical processes for converting syngas and olefins into valuable hydrocarbons and chemicals.Recent advancements in catalyst design,reaction mechanisms,and process optimization have significantly improved the efficiency,selectivity,and sustainability of these processes.This Account introduces the relevant research activities in the Research Center for Catalysis in Syngas Conversion and Fine Chemicals(DNL0805)of Dalian Institute of Chemical Physics(DICP),Chinese Academy of Sciences.The reactions of interests include FTS,heterogeneous hydroformylation of olefins,alcohol dehydration and oxidation,andα-olefin polymerization,with the emphasis on developing innovative catalysts and processes to address the challenges of traditional processes.Exemplified by the discovery of robust Co-Co_(2)C/AC for FTS and Rh_(1)/POPs-PPh_(3) for heterogeneous hydroformylation of olefins,it demonstrates how lab-scale fundamental understandings on the active sites of catalysts leads to pilot-plant scale-up and finally commercial technologies.Perspectives on the challenges and directions for future developments in these exciting fields are provided.展开更多
In this work,we consider the collapse of a D-dimensional sphere in the framework of a higher-dimensional spherically symmetric space-time in which the gravitational action chosen is claimed to be somehow linked to the...In this work,we consider the collapse of a D-dimensional sphere in the framework of a higher-dimensional spherically symmetric space-time in which the gravitational action chosen is claimed to be somehow linked to the D-dimensional modified term.This work investigates the criteria for the dynamical instability of anisotropic relativistic sphere systems with D-dimensional modified gravity.The certain conditions are applied that lead to the collapse equation and their effects on adiabatic indexΓin both Newtonian(N)and Post-Newtonian(PN)regimes by using a perturbation scheme.The study explores that theΓplays a crucial role in determining the degree of dynamical instability.This index characterizes the fluid's stiffness and has a significant impact on defining the ranges of instability.This systematic investigation demonstrates the influence of various material properties such as anisotropic pressure,kinematic quantities,mass function,D-dimensional modified gravity parameters,and the radial profile of energy density on the instability of considered structures during their evolution.This work also displays the dynamical behavior of spherically symmetric fluid configuration via graphical approaches.展开更多
Efficient production of butanediols from biomass-derived feedstocks under mild reaction conditions is still of challenge.Here,we reported a highly efficient Pd-WO_(x) catalyst which was facilely synthesized by a simpl...Efficient production of butanediols from biomass-derived feedstocks under mild reaction conditions is still of challenge.Here,we reported a highly efficient Pd-WO_(x) catalyst which was facilely synthesized by a simple‘one pot’solvothermal method for the selective conversion of glucose and lignocellulosic biomass to butanediols with remarkable activity.The optimized process achieved an impressive 56.5%yield of butanediols at 180◦C within 8 h under a low hydrogen pressure of 0.6 MPa,surpassing most reported catalysts.Comprehensive characterization(H_(2)-TPR,XPS,NH3-TPD,etc.)revealed that Pd-WO_(x) not only enhanced H_(2) adsorption and activation but also possessed a higher density of acidic sites to promote selective cleavage of C-C bond in glucose structure,thereby significantly improving the efficiency of sustainable butanediols production.Furthermore,the catalyst demonstrated excellent stability over five reaction cycles.This work provides a viable and efficient strategy for sustainable biomass valorization to produce valuable butanediols.展开更多
Coupled thermo-hydro-mechanical(THM)processes in fractured rock are playing a crucial role in geoscience and geoengineering applications.Diverse and conceptually distinct approaches have emerged over the past decades ...Coupled thermo-hydro-mechanical(THM)processes in fractured rock are playing a crucial role in geoscience and geoengineering applications.Diverse and conceptually distinct approaches have emerged over the past decades in both continuum and discontinuum perspectives leading to significant progress in their comprehending and modeling.This review paper offers an integrated perspective on existing modeling methodologies providing guidance for model selection based on the initial and boundary conditions.By comparing various models,one can better assess the uncertainties in predictions,particularly those related to the conceptual models.The review explores how these methodologies have significantlyenhanced the fundamental understanding of how fractures respond to fluid injection and production,and improved predictive capabilities pertaining to coupled processes within fractured systems.It emphasizes the importance of utilizing advanced computational technologies and thoroughly considering fundamental theories and principles established through past experimental evidence and practical experience.The selection and calibration of model parameters should be based on typical ranges and applied to the specificconditions of applications.The challenges arising from inherent heterogeneity and uncertainties,nonlinear THM coupled processes,scale dependence,and computational limitations in representing fieldscale fractures are discussed.Realizing potential advances on computational capacity calls for methodical conceptualization,mathematical modeling,selection of numerical solution strategies,implementation,and calibration to foster simulation outcomes that intricately reflectthe nuanced complexities of geological phenomena.Future research efforts should focus on innovative approaches to tackle the hurdles and advance the state-of-the-art in this critical fieldof study.展开更多
Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports t...Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports the successful hydrothermal preparation of a MgLiAlCe-LDHs@GO flm on a MAO-coated Mg–Li alloy following Ce confnement.The graphene oxide(GO)sheet increased the difusion path of the corrosive media,and the addition of rare-earth cerium ions(Ce^(3+))endowed the flm with a certain self-healing ability,which signifcantly improved the corrosion resistance of the flm,and the corrosion current density(icorr)reached 3.27×10^(−8)A cm^(−2).The synergistic action of GO and Ce^(3+)can achieve long-term corrosion protection for the substrate.The corrosion resistance mechanism of MgLiAlCe-LDHs@GO flm was discussed by the scanning vibration electrode technique(SVET).展开更多
In recent years,high-entropy alloys(HEAs)have become prominent metallic materials due to their unique design strategies and excellent mechanical properties.The HEAs-inherent high-entropy,lattice-distortion,sluggish-di...In recent years,high-entropy alloys(HEAs)have become prominent metallic materials due to their unique design strategies and excellent mechanical properties.The HEAs-inherent high-entropy,lattice-distortion,sluggish-diffusion,and cocktail effects make HEAs maintain high strength,oxidation resistance,corrosion resistance,wear resistance,and other excellent comprehensive properties,showing stronger competitiveness relative to traditional alloys.Refractory high-entropy alloys(RHEAs)are considered as a new kind of high-temperature materials with great application prospects due to their excellent mechanical properties and have the potential to replace nickel-based superalloy as the next generation of high-temperature materials.We reviewed the research status and preparation methods of RHEAs in recent years,including the metallurgical smelting,powder metallurgy,magnetron sputtering,and additive manufacturing technologies.The microstructure and phase-transformation process of RHEAs were analyzed.The mechan-ical properties and main strengthening and toughening mechanisms of RHEAs,such as solid-solution strengthening,precipitation strengthening,and the transformation-induced plasticity(TRIP),were discussed,and the deformation mechanism of RHEAs was revealed.The properties of RHEAs,including high strength,oxidation resistance,corrosion and wear resistance were reviewed.RHEAs will meet the huge market demand in the engineering materials field,but there are still many challenges,such as the tradeoff between high strength and high ductility,structural design,and performance optimization of RHEAs with brittle BCC structures.We believe that this combination of knowledge may shape the future of RHEAs and break through the mutually exclusive conundrum of high strength and high toughness for RHEAs.展开更多
With the continuous increase in human population,there is widespread usage of chemical fertilizers that are responsible for introducing abiotic stresses in agricultural crop lands.Abiotic stresses are major constraint...With the continuous increase in human population,there is widespread usage of chemical fertilizers that are responsible for introducing abiotic stresses in agricultural crop lands.Abiotic stresses are major constraints for crop yield and global food security and therefore require an immediate response.The implementation of plant growth-promoting rhizobacteria(PGPR)into the agricultural production system can be a profitable alternative because of its efficiency in plant growth regulation and abiotic stress management.These bacteria have the potential to promote plant growth and to aid in the management of plant diseases and abiotic stresses in the soil through production of bacterial phytohormones and associated metabolites as well as through significant root morphological changes.These changes result in improved plant-water relations and nutritional status in plants and stimulate plants’defensive mechanisms to overcome unfavorable environmental conditions.Here,we describe the significance of plant-microbe interactions,highlighting the role of PGPR,bacterial phytohormones,and bacterial metabolites in relieving abiotic environmental stress in soil.Further research is necessary to gather in-depth knowledge on PGPR-associated mechanisms and plant-microbe interactions in order to pave a way for field-scale application of beneficial rhizobacteria,with the aim of building a healthy and sustainable agricultural system.Therefore,this review aims to emphasize the role of PGPR in growth promotion and management of abiotic soil stress with the goal of developing an eco-friendly and cost-effective strategy for future agricultural sustainability.展开更多
We demonstrate a new approach to tune the electrical properties of graphene and functionalized graphene. Graphene was synthesized using thermal chemical vapour deposition(TCVD) method on copper foil using precursor ga...We demonstrate a new approach to tune the electrical properties of graphene and functionalized graphene. Graphene was synthesized using thermal chemical vapour deposition(TCVD) method on copper foil using precursor gas acetylene and co-catalyst H2 gas. TCVD assisted graphene was successfully transferred onto a silicon wafer. Transferred graphene sheet was then functionalized to prepare graphene oxide(GO) and reduced graphene oxide(rGO). Different surface charge carbon nanoparticles, e.g. carbon nanoparticle with net positive charge and carbon nanoparticle with net negative charge were then immobilized on transferred graphene and functionalized graphene sheets. The functionalized graphene and charge mobilized functionalized graphene were characterized by Uv–vis spectroscopy,Fourier transformed infrared spectroscopy, scanning electron microscopy, and Raman spectroscopy. After immobilization of carbon nanomaterials, the ac electrical conductivity was found to increase due to enhancement of the surface charge, electron density, and mobility. It was observed that negative surface charge immobilized graphene and functionalized graphene show higher conductivity. Thus, the electrical property of graphene and functionalized graphene can be tuned by surface modification with different surface charge carbon nanomaterials.展开更多
The study of atomically dispersed metal-nitrogen electrocatalysts is still limited in terms of understanding their catalytic mechanism because of the inability to precisely regulate the coordination number and type of...The study of atomically dispersed metal-nitrogen electrocatalysts is still limited in terms of understanding their catalytic mechanism because of the inability to precisely regulate the coordination number and type of N in combination with the metal elements.Inspired by the high catalytic activity and selectivity of natural enzymes,herein,we have designed and fabricated ultrathin carbon nanosheet-supported Mn single-atom catalysts(SACs)with a precise pyrrole-type Mn-N4(PT-MnN4)configuration using a bio-mimicking strategy.The PT-MnN4 SACs display outstanding oxygen reduction reaction(ORR)activity,with a half-wave potential(E_(1/2))of 0.88 V(vs.revisible hydrogen electrode[RHE])and extremely high stability in alkaline media.Moreover,superior ORR activities are also obtained,E_(1/2) of 0.73 V and 0.63 V in acid and neutral electrolytes,respectively,indicating the efficient pH-universal ORR performances.The assembled zinc-air battery using the PT-MnN4 SACs as air cathodes exhibits a high peak power density(175 mW cm^(−2))and long-term stability up to 150 h,implying its promising application in metal-air batteries.This study has paved the way toward the rational design and precise regulation of single-atom electrocatalysts.展开更多
Green light-emitting Ba2SiO4：Eu^2＋ phosphors co-doped with La or Y were synthesized by conventional solid-state reaction technique in reductive atmosphere（a mixture of 5% H2 and 95% N2）.The results showed that the...Green light-emitting Ba2SiO4：Eu^2＋ phosphors co-doped with La or Y were synthesized by conventional solid-state reaction technique in reductive atmosphere（a mixture of 5% H2 and 95% N2）.The results showed that the co-doping of La and Y could greatly enhance the fluorescence intensity of Ba2SiO4：Eu2＋ phosphors.The optimum doping concentration expressed by the x value in（Ba0.985-1.5xREx）2SiO4：0.03Eu^2＋（RE=La or Y） was determined to be of 0.05.The excitation and emission peaks of all as-synthesized phosphors were wide bands.The excitation bands ranged from 250 to 400 nm, which matched well with the wavelength of near ultraviolet white light-emitting diodes（LED） chip and could be used as a potential candidate for the fabrication of white LED.The emission bands from 450 to 550 nm were typical 5d-4f transition emission of Eu^2＋ and displayed un-symmetry profiles because of the two substitution sites of Ba^2＋ with Eu^2＋.展开更多
基金supported by the National Key R&D Program of China (No.2016YFF0200500)the National Natural Science Foundation of China (No.21473173, No.21590802, No.21403207, No.21503206)the Strategic Priority Research Program of Chinese Academy of Sciences (No.XDB17000000)
文摘The H+H2 reaction is the simplest chemical reaction system and has long been the prototype model in the study of reaction dynamics. Here we report a high resolution experimental investigation of the state-to-state reaction dynamics in the H+HD→H2+D reaction by using the crossed molecular beams method and velocity map ion imaging technique at the collision energy of 1.17 eV. D atom products in this reaction were probed by the near threshold 1+1'(vacuum ultraviolet+ultraviolet) laser ionization scheme. The ion image with both high angular and energy resolution were acquired. State-to-state differential cross sections was accurately derived. Fast forward scattering oscillations, relating with interference effects in the scattering process, were clearly observed for H2 products at H2(v'=0,j'=1) and H2(v'=0,j'=3) rovibrational levels. This study further demonstrates the importance of measuring high-resolution differential cross sections in the study of state-to-state reaction dynamics in the gas phase.
文摘The direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol has attracted much attention as an environmentally benign and alternative route for conventional routes.Herein,a series of cerium oxide catalysts with various textural features and surface properties were prepared by the one-pot synthesis method for the direct DMC synthesis from CO_(2)and methanol,and the structure-performance relationship was investigated in detail.Characterization results revealed that both of surface acid-base properties and the oxygen vacancies contents decreased with the rising crystallinity at increasingly higher calcination temperature accompanied by an unexpectedly volcano-shaped trend of DMC yield observed on the catalysts.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)studies indicated that the adsorption rate of methanol is slower than that of CO_(2)and the methanol activation state largely influences the formation of key intermediate.Although the enhanced surface acidity-basicity and oxygen vacancies brought by low-temperature calcination could facilitate the activation of CO_(2),the presence of excess strongly basic sites on low-crystallinity sample was detrimental to DMC synthesis due to the preferred formation of unreactive mono/polydentate carbonates as well as the further impediment of methanol activation.Moreover,with the use of 2-cyanopyridine as a dehydration reagent,the DMC synthesis was found to be both influenced by the promotion from the rapid in situ removal of water and the inhibition from the competitive adsorption of hydration products on the same active sites.
文摘The Advanced Glycation End Products(AGE)binding with its receptor can increase reactive oxygen species(ROS)generation through specific signaling mediators.The effect of superoxide(O2-)and O2-mediated ROS and reactive nitrogen species depends on their concentration and location of formation.Nitric oxide(NO)has anti-inflammatory and anticoagulant properties and a vasodilation effect,but NO can be deactivated by reacting with O_(2)^(-).This reaction between NO and O2-produces the potent oxidant ONOO−.Therefore,ONOO-'s regulatory role in AGEs in diabetic cardiovascular complications must considered as a regulator of cardiovascular complications in diabetes.
基金This work was supported by the National Natural Science Foundation of China(No.21833003 and No.21773213)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB17000000)Chinese Academy of Sciences(GJJSTD20190002).
文摘N-ethylpyrrole is one of ethylsubstituted derivatives of pyrrole and its excited-state decay dynamics has never been explored.In this work,we investigate ultrafast decay dynamics of N-ethylpyrrole excited to the S_(1)electronic state using a femtosecond time-resolved photoelectron imaging method.Two pump wavelengths of 241.9 and 237.7 nm are employed.At 241.9 nm,three time constants,5.0±0.7 ps,66.4±15.6 ps and 1.3±0.1 ns,are derived.For 237.7 nm,two time constants of 2.1±0.1 ps and 13.1±1.2 ps are derived.We assign all these time constants to be associated with different vibrational states in the S_(1)state.The possible decay mechanisms of different S_(1)vibrational states are briefly discussed.
基金supported by the National Key Research and Development Program of China for BinBin Xie(No.2019YFA0709400)the National Natural Science Foundation of China for Bin-Bin Xie(No.21903068)+1 种基金Xiang-Yang Liu(No.22003043)Natural Science Foundation of Zhejiang Province for Bin-Bin Xie(No.LQ19B030007)。
文摘Excited-state double proton transfer(ESDPT)is a controversial issue which has long been plagued with theoretical and experimental communities.Herein,we took 1,8-dihydroxy-2-naphthaldehyde(DHNA)as a prototype and used combined complete active space selfconsistent field(CASSCF)and multi-state complete active-space second-order perturbation(MS-CASPT2)methods to investigate ESDPT and excited-state deactivation pathways of DHNA.Three different tautomer minima of S1-ENOL,S1-KETO-1,and S1-KETO-2 and two crucial conical intersections of S1 S0-KETO-1 and S1 S0-KETO-2 in and between the S0 and S1 states were obtained.S1-KETO-1 and S1-KETO-2 should take responsibility for experimentally observing dual-emission bands.In addition,two-dimensional potential energy surfaces(2 D-PESs)and linear interpolated internal coordinate paths connecting relevant structures were calculated at the MS-CASPT2//CASSCF level and confirmed a stepwise ESDPT mechanism.Specifically,the first proton transfer from S1-ENOL to S1-KETO-1 is barrierless,whereas the second one from S1-KETO-1 to S1-KETO-2 demands a barrier of ca.6.0 kcal/mol.The linear interpolated internal coordinate path connecting S1-KETO-1(S1-KETO-2)and S_(1) S0-KETO-1(S1 S0-KETO-2)is uphill with a barrier of ca.12.0 kcal/mol,which will trap DHNA in the S_(1) state while therefore enabling dual-emission bands.On the other hand,the S1/S0 conical intersections would also prompt the S_(1) system to decay to the S_(0) state,which could be to certain extent suppressed by locking the rotation of the C5-C8-C9-O10 dihedral angle.These mechanistic insights are not only helpful for understanding ESDPT but also useful for designing novel molecular materials with excellent photoluminescent performances.
基金supported by the National Natural Science Foundation of China (No.21473015, No.21203016, No.41574101, No.21673232, No.21773213)the Foundation for the Author of National Excellent Doctoral Dissertation of China (No.201222)
文摘We presented an experimental apparatus combining the H-atom Rydberg tagging time-of-flight technique and the laser detonation source for studying crossed beam reactions at hyperthermal collision energies. The preliminary study of the F+D2→DF+D reaction at hyperthermal collision energy of 23.84 kJ/mol was performed. Two beam sources were used in this study: one is the hyperthermal F beam source produced by a laser detonation process, and the other is D2 beam source generated by liquid-N2 cooled pulsed valve. Vibrational state-resolved di erential cross sections (DCSs) of product for the title reaction were determined. From the product vibrational state-resolved DCS, it can be concluded that products DF(v'=0, 1, 2, 3) are predominantly distributed in the sideway and backward scattering directions at this collision energy. However, the highest vibrational excited product DF(v'=4), is clearly peaked in the forward direction. The probable dynamical origins for these forward scattering products were analyzed and discussed.
基金supported by Research Grants Council(RGC),University Grants Committee(UGC)of Hong Kong(ECS No.24304722)。
文摘We classify condensable𝐸E_(2)-algebras in a modular tensor category C up to 2-Morita equivalence.Physically,this classification provides an explicit criterion to determine when distinct condensable𝐸E_(2)-algebras yield the same condensed topological phase under a two-dimensional anyon condensation process.The relations between different condensable algebras can be translated into their module categories,interpreted physically as gapped domain walls in topological orders.As concrete examples,we interpret the categories of quantum doubles of finite groups and examples beyond group symmetries.Our framework fully elucidates the interplay among condensable𝐸E_(1)-algebras in C,condensable𝐸E_(2)-algebras in C up to 2-Morita equivalence,and Lagrangian algebras in C⊠C.
基金financially supported by the National Natural Science Foundation of China(22205205)the Science Foundation of Zhejiang Sci-Tech University(ZSTU)under Grant No.21062337-Y。
文摘The electrochemical biomass valorization of industrial by-products or pollutants using renewable electricity offers significant promise for carbon neutrality.However,the huge challenges still exist in the development of efficient bifunctional electrocatalysts.Herein,we put forward a high-efficiency coelectrolysis system by coupling the nitrite reduction reaction(NO_(2)RR)and the glycerol oxidation reaction(GOR)over a novel heterogeneous β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl catalyst.Theβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl shows excellent bifunctional performance with high Faradaic efficiencies of formate(90.1%)and NH_(3)(91.9%)at cell voltage of 1.5 V,high yield rate of formate(89.6 mg h^(-1)cm^(-2))and NH_(3)(36.07 mg h^(-1)cm^(-2))at cell voltage of 1.9 V,and superior stability in an anion exchange membrane co-electrolyzer.The in-situ Raman result confirms the unique Co/Cu-based bimetallic synergistic sites of β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl towards superior GOR performance,while the operando Fourier transform infrared spectroscopy demonstrates the improved protonation kinetics of key intermediates and optimized water dissociation ability ofβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl for high NO_(2)RR activity.Our work illuminates alternative avenues to exploit the innovative and energy-saving technology for the co-production of high-added chemicals.
基金financially supported by the National Natural Science Foundation of China(22205205)the Fundamental Research Funds of Zhejiang Sci-Tech University(ZSTU,25262157Y)the staff of beamline BL11B and BL13SSW at Shanghai Synchrotron Radiation Facility for experimental support。
文摘Developing energy-efficient nitrite-to-ammonia(NO_(2)RR)conversion technologies while simultaneously enabling the electrochemical upcycling of waste polyethylene terephthalate(PET)plastics into highvalue-added chemicals is of great significance.Herein,an atomic oxygen vacancy(V_(o))engineering is developed to optimize the catalytic performance of V_(o2)-Co(OH)F nanoarray towards the NO_(2)RR and PET-derived ethylene glycol oxidation reaction(EGOR).The optimal V_(o2)-Co(OH)F achieves an ultralow operating potential of -0.03 V vs.RHE at -100 mA cm^(-2)and a remarkable NH_(3)Faradaic efficiency(FE)of 98.4% at -0.2 V vs.RHE for NO_(2)RR,and a high formate FE of 98.03% for EGOR.Operando spectroscopic analysis and theoretical calculations revealed that oxygen vacancies play a crucial role in optimizing the electronic structure of V_(o2)-Co(OH)F,modulating the adsorption free energies of key reaction intermediates,and lowering the reaction energy barrier,thereby enhancing its overall catalytic performance.Remarkably,the V_(o2)-Co(OH)F-based NO_(2)RR||EGOR electrolyzer realized high NH_(3)and formate yield rates of 33.9 and 44.9 mg h^(-1)cm^(-2)at 1.7 V,respectively,while demonstrating outstanding long-term stability over 100 h.This work provides valuable insights into the rational design of advanced electrocatalysts for co-electrolysis systems.
文摘A combination of hard(SiCP)and soft(fly ash)particulate reinforcements could be a strategy to enhance combination of multiple properties of Magnesium and its alloys which otherwise suffer from low stiffness,low wear resistance,and many other critical properties.However,at present a comprehensive and robust map correlating different properties in particle-reinforced composites is much lacking.In this work,an industrial grade AZ91 magnesium alloy reinforced with hard SiC and soft fly ash particles(with 3 vol.%each),has been prepared using stir casting followed by hot extrusion at 325℃with a ratio of 21.5.Microstructure of the hybrid composite was characterized using optical and scanning electron microscopes.The composite exhibited a reduction in average grain size from 13.6 to 7.1μm,concomitantly an increase in Vickers hardness from 73 to 111 HV.The tension-compression yield asymmetry ratios of the unreinforced alloy and hybrid composite were 1.165 and 0.976,respectively indicating higher yield strength for the composite under compressive load.The composite exhibited 76%improvement in damping capacity under time sweep mode,and 28%improvement at 423 K under temperature sweep mode.The tribological characteristics of the composite under dry sliding conditions at sliding speeds and loads in the range of 0.5 to 1.5 m s^(-1)and 10 to 30 N,respectively showed higher wear resistance than the unreinforced alloy.The composite showed 23%improvement in sliding wear resistance at a load of 20 N and a speed of 1 m s^(-1).Finally,efforts have been made to understand the influence of one property on the other by developing statistical property correlation maps from the properties obtained in this study and from the literature.These maps are expected to help in the design of hybrid Metal Matrix Composites for a variety of targeted applications in different sectors.
文摘Fischer-Tropsch synthesis(FTS)and hydroformylation are pivotal chemical processes for converting syngas and olefins into valuable hydrocarbons and chemicals.Recent advancements in catalyst design,reaction mechanisms,and process optimization have significantly improved the efficiency,selectivity,and sustainability of these processes.This Account introduces the relevant research activities in the Research Center for Catalysis in Syngas Conversion and Fine Chemicals(DNL0805)of Dalian Institute of Chemical Physics(DICP),Chinese Academy of Sciences.The reactions of interests include FTS,heterogeneous hydroformylation of olefins,alcohol dehydration and oxidation,andα-olefin polymerization,with the emphasis on developing innovative catalysts and processes to address the challenges of traditional processes.Exemplified by the discovery of robust Co-Co_(2)C/AC for FTS and Rh_(1)/POPs-PPh_(3) for heterogeneous hydroformylation of olefins,it demonstrates how lab-scale fundamental understandings on the active sites of catalysts leads to pilot-plant scale-up and finally commercial technologies.Perspectives on the challenges and directions for future developments in these exciting fields are provided.
基金supported by Researchers Supporting Project number:RSPD2024R650,King Saud University,Riyadh,Saudi Arabia(BA)。
文摘In this work,we consider the collapse of a D-dimensional sphere in the framework of a higher-dimensional spherically symmetric space-time in which the gravitational action chosen is claimed to be somehow linked to the D-dimensional modified term.This work investigates the criteria for the dynamical instability of anisotropic relativistic sphere systems with D-dimensional modified gravity.The certain conditions are applied that lead to the collapse equation and their effects on adiabatic indexΓin both Newtonian(N)and Post-Newtonian(PN)regimes by using a perturbation scheme.The study explores that theΓplays a crucial role in determining the degree of dynamical instability.This index characterizes the fluid's stiffness and has a significant impact on defining the ranges of instability.This systematic investigation demonstrates the influence of various material properties such as anisotropic pressure,kinematic quantities,mass function,D-dimensional modified gravity parameters,and the radial profile of energy density on the instability of considered structures during their evolution.This work also displays the dynamical behavior of spherically symmetric fluid configuration via graphical approaches.
基金financial support from State Key Laboratory of Coal Mine Disaster Dynamics and Control(2011DA105287-MS202203)Chongqing Human Resources and Social Security Bureau Project(cx2024049)Natural Science Foundation of Chongqing(CSTB2022NSCQ-MSX0458).
文摘Efficient production of butanediols from biomass-derived feedstocks under mild reaction conditions is still of challenge.Here,we reported a highly efficient Pd-WO_(x) catalyst which was facilely synthesized by a simple‘one pot’solvothermal method for the selective conversion of glucose and lignocellulosic biomass to butanediols with remarkable activity.The optimized process achieved an impressive 56.5%yield of butanediols at 180◦C within 8 h under a low hydrogen pressure of 0.6 MPa,surpassing most reported catalysts.Comprehensive characterization(H_(2)-TPR,XPS,NH3-TPD,etc.)revealed that Pd-WO_(x) not only enhanced H_(2) adsorption and activation but also possessed a higher density of acidic sites to promote selective cleavage of C-C bond in glucose structure,thereby significantly improving the efficiency of sustainable butanediols production.Furthermore,the catalyst demonstrated excellent stability over five reaction cycles.This work provides a viable and efficient strategy for sustainable biomass valorization to produce valuable butanediols.
基金funding from the European Research Council(ERC)under the European Union’s Horizon 2020 Research and Innovation Program through the Starting Grant GEoREST(grant agreement No.801809)support by MICIU/AEI/10.13039/501100011033 and by"European Union Next Generation EU/PRTR"through the‘Ramón y Cajal’fellowship(reference RYC2021-032780-I)+9 种基金funding by MICIU/AEI/10.13039/501100011033 and by“ERDF,EU”through the‘HydroPoreII’project(reference PID2022-137652NBC44)support by the Institute for Korea Spent Nuclear Fuel(iKSNF)National Research Foundation of Korea(NRF)grant funded by the Korea government(Ministry of Science and ICT,MSIT)(2021M2E1A1085196)support by the Swedish Radiation Safety(SSM),Swedish Transport Administration(Trafikverket),Swedish Rock Engineering Foundation(BeFo),and Nordic Energy Research(Grant 187658)supported by the US Department of Energy(DOE),the Officeof Nuclear Energy,Spent Fuel and Waste Science and Technology Campaign,and by the US Department of Energy(DOE),the Office of Basic Energy Sciences,Chemical Sciences,Geosciences,and Biosciences Division both under Contract Number DE-AC02-05CH11231 with Lawrence Berkeley National Laboratorysupport from the US National Science Foundation(grant CMMI-2239630)funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme(grant agreement No.101002507)the UK Natural Environment Research Council(NERC)for funding SeisGreen Project(Grant No.NE/W009293/1)which supported this workthe Royal Society UK for supporting this research through fellowship UF160443IMEDEA is an accredited"Maria de Maeztu Excellence Unit"(Grant CEX2021-001198,funded by MICIU/AEI/10.13039/501100011033).
文摘Coupled thermo-hydro-mechanical(THM)processes in fractured rock are playing a crucial role in geoscience and geoengineering applications.Diverse and conceptually distinct approaches have emerged over the past decades in both continuum and discontinuum perspectives leading to significant progress in their comprehending and modeling.This review paper offers an integrated perspective on existing modeling methodologies providing guidance for model selection based on the initial and boundary conditions.By comparing various models,one can better assess the uncertainties in predictions,particularly those related to the conceptual models.The review explores how these methodologies have significantlyenhanced the fundamental understanding of how fractures respond to fluid injection and production,and improved predictive capabilities pertaining to coupled processes within fractured systems.It emphasizes the importance of utilizing advanced computational technologies and thoroughly considering fundamental theories and principles established through past experimental evidence and practical experience.The selection and calibration of model parameters should be based on typical ranges and applied to the specificconditions of applications.The challenges arising from inherent heterogeneity and uncertainties,nonlinear THM coupled processes,scale dependence,and computational limitations in representing fieldscale fractures are discussed.Realizing potential advances on computational capacity calls for methodical conceptualization,mathematical modeling,selection of numerical solution strategies,implementation,and calibration to foster simulation outcomes that intricately reflectthe nuanced complexities of geological phenomena.Future research efforts should focus on innovative approaches to tackle the hurdles and advance the state-of-the-art in this critical fieldof study.
基金supported by the National Key R&D Program of China(2021YFB3701100)the National Natural Science Foundation of China(52171101)the Fundamental Research Funds for the Central Universities(2024IAIS-QN009).
文摘Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports the successful hydrothermal preparation of a MgLiAlCe-LDHs@GO flm on a MAO-coated Mg–Li alloy following Ce confnement.The graphene oxide(GO)sheet increased the difusion path of the corrosive media,and the addition of rare-earth cerium ions(Ce^(3+))endowed the flm with a certain self-healing ability,which signifcantly improved the corrosion resistance of the flm,and the corrosion current density(icorr)reached 3.27×10^(−8)A cm^(−2).The synergistic action of GO and Ce^(3+)can achieve long-term corrosion protection for the substrate.The corrosion resistance mechanism of MgLiAlCe-LDHs@GO flm was discussed by the scanning vibration electrode technique(SVET).
文摘In recent years,high-entropy alloys(HEAs)have become prominent metallic materials due to their unique design strategies and excellent mechanical properties.The HEAs-inherent high-entropy,lattice-distortion,sluggish-diffusion,and cocktail effects make HEAs maintain high strength,oxidation resistance,corrosion resistance,wear resistance,and other excellent comprehensive properties,showing stronger competitiveness relative to traditional alloys.Refractory high-entropy alloys(RHEAs)are considered as a new kind of high-temperature materials with great application prospects due to their excellent mechanical properties and have the potential to replace nickel-based superalloy as the next generation of high-temperature materials.We reviewed the research status and preparation methods of RHEAs in recent years,including the metallurgical smelting,powder metallurgy,magnetron sputtering,and additive manufacturing technologies.The microstructure and phase-transformation process of RHEAs were analyzed.The mechan-ical properties and main strengthening and toughening mechanisms of RHEAs,such as solid-solution strengthening,precipitation strengthening,and the transformation-induced plasticity(TRIP),were discussed,and the deformation mechanism of RHEAs was revealed.The properties of RHEAs,including high strength,oxidation resistance,corrosion and wear resistance were reviewed.RHEAs will meet the huge market demand in the engineering materials field,but there are still many challenges,such as the tradeoff between high strength and high ductility,structural design,and performance optimization of RHEAs with brittle BCC structures.We believe that this combination of knowledge may shape the future of RHEAs and break through the mutually exclusive conundrum of high strength and high toughness for RHEAs.
基金the Department of Science and Technology (DST) for providing financial assistance as a Senior Research Fellow.
文摘With the continuous increase in human population,there is widespread usage of chemical fertilizers that are responsible for introducing abiotic stresses in agricultural crop lands.Abiotic stresses are major constraints for crop yield and global food security and therefore require an immediate response.The implementation of plant growth-promoting rhizobacteria(PGPR)into the agricultural production system can be a profitable alternative because of its efficiency in plant growth regulation and abiotic stress management.These bacteria have the potential to promote plant growth and to aid in the management of plant diseases and abiotic stresses in the soil through production of bacterial phytohormones and associated metabolites as well as through significant root morphological changes.These changes result in improved plant-water relations and nutritional status in plants and stimulate plants’defensive mechanisms to overcome unfavorable environmental conditions.Here,we describe the significance of plant-microbe interactions,highlighting the role of PGPR,bacterial phytohormones,and bacterial metabolites in relieving abiotic environmental stress in soil.Further research is necessary to gather in-depth knowledge on PGPR-associated mechanisms and plant-microbe interactions in order to pave a way for field-scale application of beneficial rhizobacteria,with the aim of building a healthy and sustainable agricultural system.Therefore,this review aims to emphasize the role of PGPR in growth promotion and management of abiotic soil stress with the goal of developing an eco-friendly and cost-effective strategy for future agricultural sustainability.
基金the Science and Engineering Research Board(SERB),New Delhi,for project grant SB/S1/PC-69/2012the Board of Research in Nuclear Sciences(BRNS),Mumbai,Grant No.34/14/20/2014-BRNSSERB,New Delhi,for fellowship
文摘We demonstrate a new approach to tune the electrical properties of graphene and functionalized graphene. Graphene was synthesized using thermal chemical vapour deposition(TCVD) method on copper foil using precursor gas acetylene and co-catalyst H2 gas. TCVD assisted graphene was successfully transferred onto a silicon wafer. Transferred graphene sheet was then functionalized to prepare graphene oxide(GO) and reduced graphene oxide(rGO). Different surface charge carbon nanoparticles, e.g. carbon nanoparticle with net positive charge and carbon nanoparticle with net negative charge were then immobilized on transferred graphene and functionalized graphene sheets. The functionalized graphene and charge mobilized functionalized graphene were characterized by Uv–vis spectroscopy,Fourier transformed infrared spectroscopy, scanning electron microscopy, and Raman spectroscopy. After immobilization of carbon nanomaterials, the ac electrical conductivity was found to increase due to enhancement of the surface charge, electron density, and mobility. It was observed that negative surface charge immobilized graphene and functionalized graphene show higher conductivity. Thus, the electrical property of graphene and functionalized graphene can be tuned by surface modification with different surface charge carbon nanomaterials.
基金support from the Independent Designing Scientific Research Project of Zhejiang Normal University(2020ZS03)the Zhejiang Provincial Ten Thousand Talent Program(2017R52043)+1 种基金support from the Zhejiang Province Basic Public Welfare Research Project(LGF19B070006)supported by the National Natural Science Foundation of China(No.21775138).
文摘The study of atomically dispersed metal-nitrogen electrocatalysts is still limited in terms of understanding their catalytic mechanism because of the inability to precisely regulate the coordination number and type of N in combination with the metal elements.Inspired by the high catalytic activity and selectivity of natural enzymes,herein,we have designed and fabricated ultrathin carbon nanosheet-supported Mn single-atom catalysts(SACs)with a precise pyrrole-type Mn-N4(PT-MnN4)configuration using a bio-mimicking strategy.The PT-MnN4 SACs display outstanding oxygen reduction reaction(ORR)activity,with a half-wave potential(E_(1/2))of 0.88 V(vs.revisible hydrogen electrode[RHE])and extremely high stability in alkaline media.Moreover,superior ORR activities are also obtained,E_(1/2) of 0.73 V and 0.63 V in acid and neutral electrolytes,respectively,indicating the efficient pH-universal ORR performances.The assembled zinc-air battery using the PT-MnN4 SACs as air cathodes exhibits a high peak power density(175 mW cm^(−2))and long-term stability up to 150 h,implying its promising application in metal-air batteries.This study has paved the way toward the rational design and precise regulation of single-atom electrocatalysts.
基金Program for Changjiang Scholars and Innovative Research Team in University (IRT0730)the Key Project of Department of Science and Technology of Jiangxi ProvinceProject of Education Department of Jiangxi
文摘Green light-emitting Ba2SiO4：Eu^2＋ phosphors co-doped with La or Y were synthesized by conventional solid-state reaction technique in reductive atmosphere（a mixture of 5% H2 and 95% N2）.The results showed that the co-doping of La and Y could greatly enhance the fluorescence intensity of Ba2SiO4：Eu2＋ phosphors.The optimum doping concentration expressed by the x value in（Ba0.985-1.5xREx）2SiO4：0.03Eu^2＋（RE=La or Y） was determined to be of 0.05.The excitation and emission peaks of all as-synthesized phosphors were wide bands.The excitation bands ranged from 250 to 400 nm, which matched well with the wavelength of near ultraviolet white light-emitting diodes（LED） chip and could be used as a potential candidate for the fabrication of white LED.The emission bands from 450 to 550 nm were typical 5d-4f transition emission of Eu^2＋ and displayed un-symmetry profiles because of the two substitution sites of Ba^2＋ with Eu^2＋.
