An importa nt strategy to promote voluntary movements after motor system injury is to strengthen the connections between the motor cortex and muscles by taking advantage of the plasticity of the corticospinal motor sy...An importa nt strategy to promote voluntary movements after motor system injury is to strengthen the connections between the motor cortex and muscles by taking advantage of the plasticity of the corticospinal motor system.Many neuromodulation approaches are directed to activate the spinal cord and peripheral axons to strengthen muscle activation.We discuss in this perspective that,the cortex and spinal cord should be ta rgeted together to enhance cortex-to-musclefunction(Amer and Martin,2022).展开更多
Self‐supporting ZSM‐5crystals with hierarchical porosity were prepared through a steam‐assisted crystallization method using sponges as rigid scaffolds.The synthesized materials were characterized by X‐ray diffrac...Self‐supporting ZSM‐5crystals with hierarchical porosity were prepared through a steam‐assisted crystallization method using sponges as rigid scaffolds.The synthesized materials were characterized by X‐ray diffraction,nitrogen sorption,scanning electron microscopy,transmission electron microscopy,solid‐state nuclear magnetic resonance spectroscopy and ammonia temperature‐programmed desorption.The ZSM‐5monoliths exhibited high crystallinities,hierarchical porous structures and strong acidities.They showed superior catalytic performance in the liquid‐phase esterification reaction between benzyl alcohol and hexanoic acid.展开更多
Core-shell structured nanospheres with mesoporous silica shell and Ni core(denoted as Ni@meso-SiO2) are prepared through a three-step process. Monodispersed Ni precursors are first prepared, and then coated with mesop...Core-shell structured nanospheres with mesoporous silica shell and Ni core(denoted as Ni@meso-SiO2) are prepared through a three-step process. Monodispersed Ni precursors are first prepared, and then coated with mesoporous SiO2. Final Ni@meso-SiO2spheres are obtained after calcination. The products are characterized by X-ray powder diffraction, transmission electron microscopy and N2adsorption-desorption methods. These spheres have a high surface area and are well dispersed in water, showing a high catalytic activity with a TOF value of 18.5,and outstanding stability in hydrolytic dehydrogenation of ammonia borane at room temperature.展开更多
Tile expressions of interface flee energy (IFE) of composite droplets with meniscal liquid-air interlhce in metastable state on nlicro/nano textured snrfaces were formulated. Then tile parameters to describe the men...Tile expressions of interface flee energy (IFE) of composite droplets with meniscal liquid-air interlhce in metastable state on nlicro/nano textured snrfaces were formulated. Then tile parameters to describe the meniscus were determined based on the principle of minimtun 1FE. Furthermore, the IFE barriers and the necessary and sufficient conditions of drop wetting transition fl'om Cassie to Wenzel were analyzed and the corresponding criteria were lk^rmulated. The results show that the liquid-air interface below a composite droplet is fiat when the post pitches are relatively small, but in a shape of curved meniscus when the piteches are comparatively large and the curvature depends on structural parameters. The angle between meniscus and pillar wall is just equal to the supplementary angle of intrinsic contact angle of post material. The calculations also illustrate that Cassie droplets will transform to Wenzel state when post pitch is large enough or when drop volume is sufficiently small. The opposite transition from Wenzel to Cassie state, however, is unable to take place spontaneously because the energy barrier is always positive. Finally, the calculation results of this model are well consistent with tile experimental obserwttions in literatures for the wetting transition of droplets from Cassie to Wenzel state.展开更多
Supported metal catalysts are widely used in the modern chemical industry.The electronic interaction between supports and active components is of great significance for heterogeneous catalysis.Graphdiyne(GDY),a new ty...Supported metal catalysts are widely used in the modern chemical industry.The electronic interaction between supports and active components is of great significance for heterogeneous catalysis.Graphdiyne(GDY),a new type of carbon allotrope with sp-hybridized carbon atoms,πconjugate structure,and electron transmission capability,is a promising candidate as catalyst support.Recent years have witnessed the rapid progress of GDY-supported metal catalysts for different catalysis reactions.Considering that most processes in the current chemical industry are thermocatalytic reactions,we herein give an overview about the advances and particular characteristics of GDY-supported catalysts in these reactions.The geometric structure and electronic properties of GDY are first introduced.Then,the synthesis methods for GDY-supported metal catalysts and their applications in thermocatalytic reactions are discussed,in which the effect of electronic interaction on catalytic performance is highlighted.Finally,the current challenges and future directions of GDY-supported metal catalysts for thermocatalysis are proposed.It is expected that this review will enrich our understanding of the advances of GDY as a superior support for metal catalysts in thermocatalytic reactions.展开更多
Higher alcohol synthesis(HAS)from syngas could efficiently alleviate the dependence on the traditional fossil resources.However,it is still challenging to construct high-performance HAS catalysts with satisfying selec...Higher alcohol synthesis(HAS)from syngas could efficiently alleviate the dependence on the traditional fossil resources.However,it is still challenging to construct high-performance HAS catalysts with satisfying selectivity,space–time yield(STY),and stability.Herein,we designed a diatomic catalyst by anchoring Co and Cu sites onto a hierarchical porous N-doped carbon matrix(Co/Cu–N–C).The Co/Cu–N–C is efficient for HAS and is among the best catalysts reported.With a COconversion of 81.7%,C2+OHselectivity could reach 58.5%with an outstanding C2+OH STY of 851.8 mg/g·h.We found that the N4–Co1 and Cu1–N4 showed an excellent synergistic effect.The adsorption of CO occurred on the Co site,and the surrounding nitrogen sites served as a hydrogen reservoir for the CO reduction reactions to form CHxCo.Meanwhile,the Cu sites stabilized a CHOCu species to interact with CHxCo,facilitating a barrier-free formation of C2 species,which is responsible for the high selectivity of higher alcohols.展开更多
A novel nanoadsorbent for the removal of heavy metal ions is reported.Cotton was first hydrolyzed to obtain cellulose nanocrystals(CNCs).CNCs were then chemically modified with succinic anhydride to obtain SCNCs.The...A novel nanoadsorbent for the removal of heavy metal ions is reported.Cotton was first hydrolyzed to obtain cellulose nanocrystals(CNCs).CNCs were then chemically modified with succinic anhydride to obtain SCNCs.The sodic nanoadsorbent(NaSCNCs) was further prepared by treatment of SCNCs with saturated NaHCO 3 aqueous solution.Batch experiments were carried out with SCNCs and NaSCNCs for the removal of Pb 2+ and Cd 2+.The effects of contact time,pH,initial adsorption concentration,coexisting ions and the regeneration performance were investigated.Kinetic studies showed that the adsorption equilibrium time of Pb 2+ and Cd 2+ was reached within 150 min on SCNCs and 5 min on NaSCNCs.The adsorption capacities of Pb 2+ and Cd 2+ on SCNCs and NaSCNCs increased with increasing pH.The adsorption isotherm was well fitted by the Langmuir model.The maximum adsorption capacities of SCNCs and NaSCNCs for Pb 2+ and Cd 2+ were 367.6 mg/g,259.7 mg/g and 465.1 mg/g,344.8 mg/g,respectively.SCNCs and NaSCNCs showed high selectivity and interference resistance from coexisting ions for the adsorption of Pb 2+.NaSCNCs could be efficiently regenerated with a mild saturated NaCl solution with no loss of capacity after two recycles.The adsorption mechanisms of SCNCs and NaSCNCs were discussed.展开更多
The influences of finite-size effects on the self-organized criticality (SOC) of the traditional forest-fire model are investigated by means of a new method. The forest size is originally set to a value much greater t...The influences of finite-size effects on the self-organized criticality (SOC) of the traditional forest-fire model are investigated by means of a new method. The forest size is originally set to a value much greater than the correla-tion length of the forest. Finite-size effects are then studied by equally dividing the forest into more and more separate subsystems on condition that the forest size, igniting prob-ability and planting probability are invariant. A new phe-nomenon, i.e. the finite-size effects with one-side frequency peak, is observed. The boundary between two neighboring subsystems can be regarded as a firebreak. The concept of ’separation ability’ is introduced to represent the probability for the firebreak to block off the fire successfully. Restrain-ing effects of separation ability on finite-size effects are ana-lyzed. Finite-size effects and separation ability, as well as their relations are found to have practical importance to the actual forest-fire protection.展开更多
Inorganic-organic hybrid WOx-ethylenediamine (WO/-EDA) nanowires have been produced by a simple, low-cost and high-yield solvothermal method. These WO/-EDA hybrid nanowires have unique lamellar mesostructures with a...Inorganic-organic hybrid WOx-ethylenediamine (WO/-EDA) nanowires have been produced by a simple, low-cost and high-yield solvothermal method. These WO/-EDA hybrid nanowires have unique lamellar mesostructures with an alternate stacking of an interconnected [WO6] octahedral layer and a monolayer of ethylenediamine molecules. This hybrid structure integrated the functionality of ethylenediamine with the stability of the WOx frameworks. In situ synchrotron- radiation X-ray diffraction is used to elucidate a possible formation mechanism of the hybrid WOx-EDA. The nanowire morphology, lamellar structure and abundant functional amino groups endow them with versatile abilities. For example, in heavy metal ion adsorption the WOx-EDA nanowires display exceptional adsorption capabilities of 925 mg·g^-1 for Pb^2+ and 610 mg·g^-1 for UO2^2+. The nanowires also show outstanding stability and activity as a heterogeneous base catalyst in the Knoevenagel condensation reaction at room temperature. The catalyst can be recycled and reused for 20 cycles with nearly 100% yields. This study provides a new strategy to design inorganic-organic hybrid materials, and offers a multifunctional material that is a highly efficient adsorbent and sustainable catalyst.展开更多
Selective transfer hydrogenation of nitroarenes to amines with transition metal nanocatalysts is appealing due to its low-cost, moderate reaction conditions, good activity and excellent selectivity. Single-atom cataly...Selective transfer hydrogenation of nitroarenes to amines with transition metal nanocatalysts is appealing due to its low-cost, moderate reaction conditions, good activity and excellent selectivity. Single-atom catalysts (SACs) possessing advantages of maximum atom efficiency and particular electronic structure are expected to be more effective for this reaction, yet no report about it. Herein, cobalt single atoms anchored on N-doped ultrathin carbon nanosheets (denoted as CoSAs/NCNS) were produced and demonstrated as an outstanding SAC for selective transfer hydrogenation of nitroarenes to amines with formic acid as hydrogen donor. The turnover frequency (TOF) reached 110.6 h^-1, which was 20 times higher than the best results of cobalt nanopartides reported in literatures under similar reaction conditions. Moreover, CoSAs/NCNS exhibited excellent selectivity for a variety of nitroarenes bearing other reducible functionalities, such as iodo, cyano, keto, vinyl, alkynyl and ester groups. The findings further highlight the ability and advantages of SACs in heterogeneous catalysis.展开更多
An in situ method has been used to load Cu_(2)O nanoparticles on the surface of a hydroxyl group rich TiO_(2)precursor.Cu_(2)O nanoparticles are formed by in situ reduction of Cu(OH)_(2) with Sn^(2+)ions linked to the...An in situ method has been used to load Cu_(2)O nanoparticles on the surface of a hydroxyl group rich TiO_(2)precursor.Cu_(2)O nanoparticles are formed by in situ reduction of Cu(OH)_(2) with Sn^(2+)ions linked to the surface of the TiO_(2)precursor.The initial Cu_(2)O nanoparticles serve as seeds for subsequent particle growth.The resulting Cu_(2)O nanoparticles are evenly dispersed on the surface of the TiO_(2)precursor,and are heat and air stable.The as-prepared composite is an excellent catalyst for Ullmann type cross coupling reactions of aryl halides with phenol.The composite catalyst also showed good stability,remaining highly active after five consecutive runs.展开更多
Single-atom catalysts(SACs)with the advantages of homogeneous and heterogeneous catalysts have become a hot-spot in catalysis field.However,for lack of metal–metal bond in SACs,H_(2)has to go through heterolytic diss...Single-atom catalysts(SACs)with the advantages of homogeneous and heterogeneous catalysts have become a hot-spot in catalysis field.However,for lack of metal–metal bond in SACs,H_(2)has to go through heterolytic dissociation pathway,which has higher barrier than homolytic dissociation pathway,and thus limits the hydrogenation activity of SACs.Herein,we propose and demonstrate through constructing synergistic iridium single atoms and nanoparticles co-existed catalyst(denoted as Ir_(1+NPs)/CMK)to boost the catalytic activity of quinoline hydrogenation.Both experimental and density functional theory calculation results confirm that Ir_(1)single sites activate quinoline,while Ir nanoparticles boost hydrogen dissociation.H atoms generated at Ir nanoparticles migrate to the quinoline bounded Ir_(1)single sites to complete hydrogenation.The Ir_(1+NPs)/CMK catalyst exhibits much higher reactivity with turnover frequency of 7,800 h^(−1)than those counterpart Ir_(1)/CMK and IrNPs/CMK catalysts,and is 20,000 times higher activity of commercial Ir/C benchmark catalyst for hydrogenation of quinoline under the same reaction conditions.This synergistic catalysis strategy between single atoms and nanoparticles provides a solution to further improve the performance of SACs for hydrogenation.展开更多
Polymerized fullerene hollow spheres bonded with 2,2,6,6-tetramethylpiperidine-l-oxyl (TEMPO) have been successfully synthesized via amination of C6o with 4-amino-TEMPO in the presence of H202, and then cross- linke...Polymerized fullerene hollow spheres bonded with 2,2,6,6-tetramethylpiperidine-l-oxyl (TEMPO) have been successfully synthesized via amination of C6o with 4-amino-TEMPO in the presence of H202, and then cross- linked by 1,6-hexanediamine. The hollow spheres were analyzed by fourier transform infrared spectrometer, electron spin resonance and X-ray photoelectron spec- troscopy analysis, which indicated the presence of N-O free radicals in the products. When used as a typical heterogeneous catalyst for selective oxidation of alcohols to the corresponding aldehydes or ketones, it exhibited excellent activities, selectivity and recyclability. This synthesis route is convenient and effective, and may provide a new approach to developing immobilized full- erene based heterogeneous catalysts with high activity and recyclability.展开更多
Ionic liquids(ILs)have the advantages of low cost,eco-friendliness,abundant heteroatoms,excellent solubility,and coordinated ability with metal ions.These features make ILs a suitable precursor for fabricating metal s...Ionic liquids(ILs)have the advantages of low cost,eco-friendliness,abundant heteroatoms,excellent solubility,and coordinated ability with metal ions.These features make ILs a suitable precursor for fabricating metal singleatom catalysts(SACs).Herein,we prepared various metal single atoms anchored on ultrathin N-doped nanosheets(denoted as Cu_(1)/NC,Fe_(1)/NC,Co_(1)/NC,Ni_(1)/NC,and Pd_(1)/NC)by direct pyrolysis using ILs and g-C_(3)N_(4)nanosheets as templates.Taking benzene oxidation to phenol with H_(2)O_(2)as a model reaction to evaluate their catalytic performance and potential applications,Cu_(1)/NC calcined at 1000℃(denoted as Cu1/NC-1000)exhibits the highest activity with a turnover frequency of about 200 h^(-1)in the first 1 h at 60℃,which is better than that of most metal SACs reported in the literature.High benzene conversion of 82% with high phenol selectivity of 96% and excellent recyclability were achieved using the Cu_(1)/NC-1000 catalyst.This study provides an efficient general strategy for fabricating SACs using ILs for catalytic applications.展开更多
Conversion of waste biomass to valuable carbonaceous material is a sustainable and environmental benign method for energy and reduction of greenhouse gas emission. Herein, a two-step hydrothermal method was developed ...Conversion of waste biomass to valuable carbonaceous material is a sustainable and environmental benign method for energy and reduction of greenhouse gas emission. Herein, a two-step hydrothermal method was developed to fabricate high performance electrode material from pomelo peels. In the first step, the pomelo peels were transformed to carbonaceous aerogel (CA), which constructed of three- dimensional, sponge-like brown monolith with hierarchical pores, low-density (0.032 g]cm3) and excel- lent mechanical flexibility. Then, the cobalt nickel aluminum layered double hydroxide (CoNiAI-LDH) was in situ loaded on the surface of CA to form exquisite core-shell structure (CoNiAI-LDH@CA) through the second hydrothermal step. When used as an electrode material for supercapacitor, CoNiA1-LDHOCA exhibited high specific capacitances of 1,134F/g at 1A/g and 902Fig at 10A/g, respectively. Furthermore, they displayed an excellent cycling stability without an obvious capacitance decrease after 4,000 cycles.展开更多
MXenes are promising supports for anchoring metal single atoms due to their versatile composition,well-defined nanostructures,and suitable conductivity.However,metal single atoms are usually coordinated with surface t...MXenes are promising supports for anchoring metal single atoms due to their versatile composition,well-defined nanostructures,and suitable conductivity.However,metal single atoms are usually coordinated with surface terminal groups(-O,-OH,-Cl,etc.)of MXenes via conventional wet-impregnation,resulting in limited electronic structure modification.Through a NiCl2 molten salt etching method,we observed that Ni single atoms could be in-situ doped in the lattice of MXenes analogue TiC_(0.5)N_(0.5) support(denoted as Ni1/TiC0.5N0.5),resulting in much larger charge transfer from Ni atoms to adjacent Ti atoms,and thus increasing the electronic density of these Ti atoms.When used for NO_(2) sensing,Ni_(1)/TiC_(0.5)N_(0.5) exhibited excellent response sensitivity(ultra-low limit of detection~10 ppb),selectivity,and good stability at room temperature.This study provides an effective strategy for producing MXenes analogue supported metal single atoms for potential application in gas sensing.展开更多
Single atom catalysts(SACs)with metal_(1)-N_(x)sites have shown promising activity and selectivity in direct catalytic oxidation of benzene to phenol.The reaction pathway is considered to be involving two steps,includ...Single atom catalysts(SACs)with metal_(1)-N_(x)sites have shown promising activity and selectivity in direct catalytic oxidation of benzene to phenol.The reaction pathway is considered to be involving two steps,including a H_(2)O_(2)molecule dissociated on the metal single site to form the(metal_(1)-N_(x))=O active site,and followed by the dissociation of another H_(2)O_(2)on the other side of metal atom to form O=(metal_(1)-N_(x))=O intermediate center,which is active for the adsorption of benzene molecule via the formation of a C-O bond to form phenol.In this manuscript,we report a Cu SAC with nitrogen and oxygen dual-coordination(Cu1-N3O1 moiety)that doesn’t need the first H_(2)O_(2)activation process,as verified by both experimental and density function theory(DFT)calculations results.Compared with the counterpart nitrogen-coordinated Cu SAC(denoted as Cu1/NC),Cu SAC with nitrogen and oxygen dual-coordination(denoted as Cu1/NOC)exhibits 2.5 times higher turnover frequency(TOF)and 1.6 times higher utilization efficiency of H_(2)O_(2).Particularly,the coordination number(CN)of Cu atom in Cu1/NOC maintains four even after H_(2)O_(2)treatment and reaction.Combining DFT calculations,the dynamic evolution of single atomic Cu with nitrogen and oxygen dualcoordination in hydroxylation of benzene is proposed.These findings provide an efficient route to improve the catalytic performance through regulating the coordination environments of SACs and demonstrate a new reaction mechanism in hydroxylation of benzene to phenol reaction.展开更多
Two types of ordered mesoporous ZSM-5 zeolites with different mesopores were synthesized by a two-step method. First, carbonaceous SBA- 15 was produced by in situ carbonization of SBA- 15/P 123 composite. Then the obt...Two types of ordered mesoporous ZSM-5 zeolites with different mesopores were synthesized by a two-step method. First, carbonaceous SBA- 15 was produced by in situ carbonization of SBA- 15/P 123 composite. Then the obtained SBA- 15/C composite was transformed into crystallized mesoporous ZSM-5 by impregnation TPAOH followed by steam-assisted crystallization. The final calcined samples synthesized with typical SBA-15/P 123 precursor showed a wormlike morphology with the mean mesopore size of 4.6 nm, while samples synthesized with the addition of trimethylbenzene as swelling agent in the precursor exhibited the morphology of microsphere with the mesopore size of about 9.5 nm. Both two types of mesoporous ZSM-5 zeolites exhibited large surface area and mesopore structure. The steam-assisted crystallization (SAC) was performed with lower consumption of solvents. This two-step method may also be suitable for synthesizing other ordered mesoporous zeolites used as catalysts in some catatytic processes.展开更多
Three-dimensional (3D) self-assembled nanomaterials with hierarchical architectures are very attractive materials due to their superior physical and chemical properties [1-7]. Over the past few years, a variety of nan...Three-dimensional (3D) self-assembled nanomaterials with hierarchical architectures are very attractive materials due to their superior physical and chemical properties [1-7]. Over the past few years, a variety of nanomaterials with well-controlled structures were developed and applied in many areas, including water treatment, energy, sensor and catalysis [8-16].展开更多
Detection of ppb-level NO_(2) gas under atmosphere is urgent to meet the requirements of the rapidly developing internet of things.Compared with traditional sensing methods,light illumination has been considered as a ...Detection of ppb-level NO_(2) gas under atmosphere is urgent to meet the requirements of the rapidly developing internet of things.Compared with traditional sensing methods,light illumination has been considered as a key approach for excellent gas sensor performance under moderate conditions.Herein,we developed a green-light-assisted gas sensor based on cadmium sulfide nanowires(CdS NWs)that has good NO_(2) sensing capability at ambient temperature.The response values of NO_(2) are 236%and 11%to 10 ppm and 12.5 ppb,respectively.Furthermore,the CdS NWs sensor has a high selectivity for NO_(2) over a variety of interference gases,as well as good stability.The cleaning light activation and the sulfur vacancy-trapped charge behavior of CdS NWs are observed,which suggest a light-assisted sensing mechanism.These results suggest that light-induced charge separation behavior might significantly improve gas-sensing characteristics.展开更多
文摘An importa nt strategy to promote voluntary movements after motor system injury is to strengthen the connections between the motor cortex and muscles by taking advantage of the plasticity of the corticospinal motor system.Many neuromodulation approaches are directed to activate the spinal cord and peripheral axons to strengthen muscle activation.We discuss in this perspective that,the cortex and spinal cord should be ta rgeted together to enhance cortex-to-musclefunction(Amer and Martin,2022).
基金supported by the National Natural Science Foundation of China(21333009)the Youth Innovation Promotion Association of CAS(2017049)~~
文摘Self‐supporting ZSM‐5crystals with hierarchical porosity were prepared through a steam‐assisted crystallization method using sponges as rigid scaffolds.The synthesized materials were characterized by X‐ray diffraction,nitrogen sorption,scanning electron microscopy,transmission electron microscopy,solid‐state nuclear magnetic resonance spectroscopy and ammonia temperature‐programmed desorption.The ZSM‐5monoliths exhibited high crystallinities,hierarchical porous structures and strong acidities.They showed superior catalytic performance in the liquid‐phase esterification reaction between benzyl alcohol and hexanoic acid.
基金supported by the National Basic Research Program of China(MOST 2009CB930400)the National Natural Science Foundation of China(21121063)the Chinese Academy of Sciences(KJCX2-YW-N41)
文摘Core-shell structured nanospheres with mesoporous silica shell and Ni core(denoted as Ni@meso-SiO2) are prepared through a three-step process. Monodispersed Ni precursors are first prepared, and then coated with mesoporous SiO2. Final Ni@meso-SiO2spheres are obtained after calcination. The products are characterized by X-ray powder diffraction, transmission electron microscopy and N2adsorption-desorption methods. These spheres have a high surface area and are well dispersed in water, showing a high catalytic activity with a TOF value of 18.5,and outstanding stability in hydrolytic dehydrogenation of ammonia borane at room temperature.
基金Project supported by the National Natural Science Foundation of China(Grant No.21676041)
文摘Tile expressions of interface flee energy (IFE) of composite droplets with meniscal liquid-air interlhce in metastable state on nlicro/nano textured snrfaces were formulated. Then tile parameters to describe the meniscus were determined based on the principle of minimtun 1FE. Furthermore, the IFE barriers and the necessary and sufficient conditions of drop wetting transition fl'om Cassie to Wenzel were analyzed and the corresponding criteria were lk^rmulated. The results show that the liquid-air interface below a composite droplet is fiat when the post pitches are relatively small, but in a shape of curved meniscus when the piteches are comparatively large and the curvature depends on structural parameters. The angle between meniscus and pillar wall is just equal to the supplementary angle of intrinsic contact angle of post material. The calculations also illustrate that Cassie droplets will transform to Wenzel state when post pitch is large enough or when drop volume is sufficiently small. The opposite transition from Wenzel to Cassie state, however, is unable to take place spontaneously because the energy barrier is always positive. Finally, the calculation results of this model are well consistent with tile experimental obserwttions in literatures for the wetting transition of droplets from Cassie to Wenzel state.
基金We thank the National Key R&D Program of China(Nos.2018YFA0208504 and 2018YFA0703503)the National Natural Science Foundation of China(Nos.92161112,21932006,and 22272181)the Youth Innovation Promotion Association of CAS(No.Y2017049)for financial support.
文摘Supported metal catalysts are widely used in the modern chemical industry.The electronic interaction between supports and active components is of great significance for heterogeneous catalysis.Graphdiyne(GDY),a new type of carbon allotrope with sp-hybridized carbon atoms,πconjugate structure,and electron transmission capability,is a promising candidate as catalyst support.Recent years have witnessed the rapid progress of GDY-supported metal catalysts for different catalysis reactions.Considering that most processes in the current chemical industry are thermocatalytic reactions,we herein give an overview about the advances and particular characteristics of GDY-supported catalysts in these reactions.The geometric structure and electronic properties of GDY are first introduced.Then,the synthesis methods for GDY-supported metal catalysts and their applications in thermocatalytic reactions are discussed,in which the effect of electronic interaction on catalytic performance is highlighted.Finally,the current challenges and future directions of GDY-supported metal catalysts for thermocatalysis are proposed.It is expected that this review will enrich our understanding of the advances of GDY as a superior support for metal catalysts in thermocatalytic reactions.
基金the National Key Research and Development Program of China(grant nos.2019YFB1503903,2019YFB1503904,and 2018YFB1501403)The Natural Science Foundation of Fujian Province of China(grant no.2019J06005).
文摘Higher alcohol synthesis(HAS)from syngas could efficiently alleviate the dependence on the traditional fossil resources.However,it is still challenging to construct high-performance HAS catalysts with satisfying selectivity,space–time yield(STY),and stability.Herein,we designed a diatomic catalyst by anchoring Co and Cu sites onto a hierarchical porous N-doped carbon matrix(Co/Cu–N–C).The Co/Cu–N–C is efficient for HAS and is among the best catalysts reported.With a COconversion of 81.7%,C2+OHselectivity could reach 58.5%with an outstanding C2+OH STY of 851.8 mg/g·h.We found that the N4–Co1 and Cu1–N4 showed an excellent synergistic effect.The adsorption of CO occurred on the Co site,and the surrounding nitrogen sites served as a hydrogen reservoir for the CO reduction reactions to form CHxCo.Meanwhile,the Cu sites stabilized a CHOCu species to interact with CHxCo,facilitating a barrier-free formation of C2 species,which is responsible for the high selectivity of higher alcohols.
基金supported by the National Basic Research Program (973) of China (No. 2011CB933700) of Ministry of Science and Technology of China
文摘A novel nanoadsorbent for the removal of heavy metal ions is reported.Cotton was first hydrolyzed to obtain cellulose nanocrystals(CNCs).CNCs were then chemically modified with succinic anhydride to obtain SCNCs.The sodic nanoadsorbent(NaSCNCs) was further prepared by treatment of SCNCs with saturated NaHCO 3 aqueous solution.Batch experiments were carried out with SCNCs and NaSCNCs for the removal of Pb 2+ and Cd 2+.The effects of contact time,pH,initial adsorption concentration,coexisting ions and the regeneration performance were investigated.Kinetic studies showed that the adsorption equilibrium time of Pb 2+ and Cd 2+ was reached within 150 min on SCNCs and 5 min on NaSCNCs.The adsorption capacities of Pb 2+ and Cd 2+ on SCNCs and NaSCNCs increased with increasing pH.The adsorption isotherm was well fitted by the Langmuir model.The maximum adsorption capacities of SCNCs and NaSCNCs for Pb 2+ and Cd 2+ were 367.6 mg/g,259.7 mg/g and 465.1 mg/g,344.8 mg/g,respectively.SCNCs and NaSCNCs showed high selectivity and interference resistance from coexisting ions for the adsorption of Pb 2+.NaSCNCs could be efficiently regenerated with a mild saturated NaCl solution with no loss of capacity after two recycles.The adsorption mechanisms of SCNCs and NaSCNCs were discussed.
基金This work was supported by the National Basic Research "973" Project in China the National Natural Science Foundation in China (Grant Nos. 59876039, 59936140 and 39970621).
文摘The influences of finite-size effects on the self-organized criticality (SOC) of the traditional forest-fire model are investigated by means of a new method. The forest size is originally set to a value much greater than the correla-tion length of the forest. Finite-size effects are then studied by equally dividing the forest into more and more separate subsystems on condition that the forest size, igniting prob-ability and planting probability are invariant. A new phe-nomenon, i.e. the finite-size effects with one-side frequency peak, is observed. The boundary between two neighboring subsystems can be regarded as a firebreak. The concept of ’separation ability’ is introduced to represent the probability for the firebreak to block off the fire successfully. Restrain-ing effects of separation ability on finite-size effects are ana-lyzed. Finite-size effects and separation ability, as well as their relations are found to have practical importance to the actual forest-fire protection.
基金Acknowledgements We are grateful for financial support from the National Basic Research Program of China (2009CB930400), the National Natural Science Foundation of China (NSFC 21121063) and the Joint Research Project funding (GJHZ1224) from the Chinese Academy of Sciences and the Commonwealth Scientific and Industrial Research Organisation (CSIRO). We thank the Institute of Modem Physics, Chinese Academy of Sciences for providing the UO2(NO3)2"6H20 salts and uranium content measurements. We acknowledge the Australian Synchrotron for access to the Powder Diffraction beamline. We thank Ian Madsen (CSIRO Process Science and Engineering) for providing access to the in situ XRD instrument and for a critical reading of the manuscript. The CSIRO Office of the Chief Executive (OCE) Postdoctoral and Science Leader Schemes are acknowledged for supporting this work. R. A. C. acknowledges the Australian Research Council for a Future Fellowship (FT0990583).
文摘Inorganic-organic hybrid WOx-ethylenediamine (WO/-EDA) nanowires have been produced by a simple, low-cost and high-yield solvothermal method. These WO/-EDA hybrid nanowires have unique lamellar mesostructures with an alternate stacking of an interconnected [WO6] octahedral layer and a monolayer of ethylenediamine molecules. This hybrid structure integrated the functionality of ethylenediamine with the stability of the WOx frameworks. In situ synchrotron- radiation X-ray diffraction is used to elucidate a possible formation mechanism of the hybrid WOx-EDA. The nanowire morphology, lamellar structure and abundant functional amino groups endow them with versatile abilities. For example, in heavy metal ion adsorption the WOx-EDA nanowires display exceptional adsorption capabilities of 925 mg·g^-1 for Pb^2+ and 610 mg·g^-1 for UO2^2+. The nanowires also show outstanding stability and activity as a heterogeneous base catalyst in the Knoevenagel condensation reaction at room temperature. The catalyst can be recycled and reused for 20 cycles with nearly 100% yields. This study provides a new strategy to design inorganic-organic hybrid materials, and offers a multifunctional material that is a highly efficient adsorbent and sustainable catalyst.
基金the financial support from the National Key R&D Program of China(2018YFA0208504)the National Natural Science Foundation of China(21573244 and21573245)the Youth Innovation Promotion Association of CAS(2017049)
文摘Selective transfer hydrogenation of nitroarenes to amines with transition metal nanocatalysts is appealing due to its low-cost, moderate reaction conditions, good activity and excellent selectivity. Single-atom catalysts (SACs) possessing advantages of maximum atom efficiency and particular electronic structure are expected to be more effective for this reaction, yet no report about it. Herein, cobalt single atoms anchored on N-doped ultrathin carbon nanosheets (denoted as CoSAs/NCNS) were produced and demonstrated as an outstanding SAC for selective transfer hydrogenation of nitroarenes to amines with formic acid as hydrogen donor. The turnover frequency (TOF) reached 110.6 h^-1, which was 20 times higher than the best results of cobalt nanopartides reported in literatures under similar reaction conditions. Moreover, CoSAs/NCNS exhibited excellent selectivity for a variety of nitroarenes bearing other reducible functionalities, such as iodo, cyano, keto, vinyl, alkynyl and ester groups. The findings further highlight the ability and advantages of SACs in heterogeneous catalysis.
基金We gratefully thank the National Natural Science Foundation of China(NSFC)(Nos.50725207,20873156,and 20821003)the National Basic Research Program of China(MOST)(Nos.2007CB-936400 and 2009CB930400)the Chinese Academy of Sciences for financial supports.
文摘An in situ method has been used to load Cu_(2)O nanoparticles on the surface of a hydroxyl group rich TiO_(2)precursor.Cu_(2)O nanoparticles are formed by in situ reduction of Cu(OH)_(2) with Sn^(2+)ions linked to the surface of the TiO_(2)precursor.The initial Cu_(2)O nanoparticles serve as seeds for subsequent particle growth.The resulting Cu_(2)O nanoparticles are evenly dispersed on the surface of the TiO_(2)precursor,and are heat and air stable.The as-prepared composite is an excellent catalyst for Ullmann type cross coupling reactions of aryl halides with phenol.The composite catalyst also showed good stability,remaining highly active after five consecutive runs.
基金the National Natural Science Foundation of China(Nos.92161112 and 21932006)the National Key Research and Development Program of China(Nos.2018YFA0208504 and 2018YFA0703503)+1 种基金the Youth Innovation Promotion Association of CAS(No.2017049)the National Science Basic Program of Shaanxi(No.S2020-JC-WT-0001).
文摘Single-atom catalysts(SACs)with the advantages of homogeneous and heterogeneous catalysts have become a hot-spot in catalysis field.However,for lack of metal–metal bond in SACs,H_(2)has to go through heterolytic dissociation pathway,which has higher barrier than homolytic dissociation pathway,and thus limits the hydrogenation activity of SACs.Herein,we propose and demonstrate through constructing synergistic iridium single atoms and nanoparticles co-existed catalyst(denoted as Ir_(1+NPs)/CMK)to boost the catalytic activity of quinoline hydrogenation.Both experimental and density functional theory calculation results confirm that Ir_(1)single sites activate quinoline,while Ir nanoparticles boost hydrogen dissociation.H atoms generated at Ir nanoparticles migrate to the quinoline bounded Ir_(1)single sites to complete hydrogenation.The Ir_(1+NPs)/CMK catalyst exhibits much higher reactivity with turnover frequency of 7,800 h^(−1)than those counterpart Ir_(1)/CMK and IrNPs/CMK catalysts,and is 20,000 times higher activity of commercial Ir/C benchmark catalyst for hydrogenation of quinoline under the same reaction conditions.This synergistic catalysis strategy between single atoms and nanoparticles provides a solution to further improve the performance of SACs for hydrogenation.
文摘Polymerized fullerene hollow spheres bonded with 2,2,6,6-tetramethylpiperidine-l-oxyl (TEMPO) have been successfully synthesized via amination of C6o with 4-amino-TEMPO in the presence of H202, and then cross- linked by 1,6-hexanediamine. The hollow spheres were analyzed by fourier transform infrared spectrometer, electron spin resonance and X-ray photoelectron spec- troscopy analysis, which indicated the presence of N-O free radicals in the products. When used as a typical heterogeneous catalyst for selective oxidation of alcohols to the corresponding aldehydes or ketones, it exhibited excellent activities, selectivity and recyclability. This synthesis route is convenient and effective, and may provide a new approach to developing immobilized full- erene based heterogeneous catalysts with high activity and recyclability.
基金the financial support from the National Key R&D Program of China(2018YFA0208504 and 2018YFA0703503)the National Natural Science Foundation of China(21932006)the Youth Innovation Promotion Association of CAS(2017049).
文摘Ionic liquids(ILs)have the advantages of low cost,eco-friendliness,abundant heteroatoms,excellent solubility,and coordinated ability with metal ions.These features make ILs a suitable precursor for fabricating metal singleatom catalysts(SACs).Herein,we prepared various metal single atoms anchored on ultrathin N-doped nanosheets(denoted as Cu_(1)/NC,Fe_(1)/NC,Co_(1)/NC,Ni_(1)/NC,and Pd_(1)/NC)by direct pyrolysis using ILs and g-C_(3)N_(4)nanosheets as templates.Taking benzene oxidation to phenol with H_(2)O_(2)as a model reaction to evaluate their catalytic performance and potential applications,Cu_(1)/NC calcined at 1000℃(denoted as Cu1/NC-1000)exhibits the highest activity with a turnover frequency of about 200 h^(-1)in the first 1 h at 60℃,which is better than that of most metal SACs reported in the literature.High benzene conversion of 82% with high phenol selectivity of 96% and excellent recyclability were achieved using the Cu_(1)/NC-1000 catalyst.This study provides an efficient general strategy for fabricating SACs using ILs for catalytic applications.
基金supported by the National Natural Science Foundation of China(21333009,21273244,21573245)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2017049)
文摘Conversion of waste biomass to valuable carbonaceous material is a sustainable and environmental benign method for energy and reduction of greenhouse gas emission. Herein, a two-step hydrothermal method was developed to fabricate high performance electrode material from pomelo peels. In the first step, the pomelo peels were transformed to carbonaceous aerogel (CA), which constructed of three- dimensional, sponge-like brown monolith with hierarchical pores, low-density (0.032 g]cm3) and excel- lent mechanical flexibility. Then, the cobalt nickel aluminum layered double hydroxide (CoNiAI-LDH) was in situ loaded on the surface of CA to form exquisite core-shell structure (CoNiAI-LDH@CA) through the second hydrothermal step. When used as an electrode material for supercapacitor, CoNiA1-LDHOCA exhibited high specific capacitances of 1,134F/g at 1A/g and 902Fig at 10A/g, respectively. Furthermore, they displayed an excellent cycling stability without an obvious capacitance decrease after 4,000 cycles.
基金National Key R&D Program of China(No.2018YFA0208504)the National Natural Science Foundation of China(Nos.21932006 and 92161112)+1 种基金the National Science Basic Research Program of Shaanxi(Nos.S2020-JC-WT-0001 and 2021JCW-20)the Youth Innovation Promotion Association of CAS(No.Y2017049)for financial support.
文摘MXenes are promising supports for anchoring metal single atoms due to their versatile composition,well-defined nanostructures,and suitable conductivity.However,metal single atoms are usually coordinated with surface terminal groups(-O,-OH,-Cl,etc.)of MXenes via conventional wet-impregnation,resulting in limited electronic structure modification.Through a NiCl2 molten salt etching method,we observed that Ni single atoms could be in-situ doped in the lattice of MXenes analogue TiC_(0.5)N_(0.5) support(denoted as Ni1/TiC0.5N0.5),resulting in much larger charge transfer from Ni atoms to adjacent Ti atoms,and thus increasing the electronic density of these Ti atoms.When used for NO_(2) sensing,Ni_(1)/TiC_(0.5)N_(0.5) exhibited excellent response sensitivity(ultra-low limit of detection~10 ppb),selectivity,and good stability at room temperature.This study provides an effective strategy for producing MXenes analogue supported metal single atoms for potential application in gas sensing.
基金We thank the National Key R&D Program of China(Nos.2018YFA0703503 and 2018YFA0208504)the National Natural Science Foundation of China(No.21932006)the Youth Innovation Promotion Association of CAS(No.2017049)for financial support.
文摘Single atom catalysts(SACs)with metal_(1)-N_(x)sites have shown promising activity and selectivity in direct catalytic oxidation of benzene to phenol.The reaction pathway is considered to be involving two steps,including a H_(2)O_(2)molecule dissociated on the metal single site to form the(metal_(1)-N_(x))=O active site,and followed by the dissociation of another H_(2)O_(2)on the other side of metal atom to form O=(metal_(1)-N_(x))=O intermediate center,which is active for the adsorption of benzene molecule via the formation of a C-O bond to form phenol.In this manuscript,we report a Cu SAC with nitrogen and oxygen dual-coordination(Cu1-N3O1 moiety)that doesn’t need the first H_(2)O_(2)activation process,as verified by both experimental and density function theory(DFT)calculations results.Compared with the counterpart nitrogen-coordinated Cu SAC(denoted as Cu1/NC),Cu SAC with nitrogen and oxygen dual-coordination(denoted as Cu1/NOC)exhibits 2.5 times higher turnover frequency(TOF)and 1.6 times higher utilization efficiency of H_(2)O_(2).Particularly,the coordination number(CN)of Cu atom in Cu1/NOC maintains four even after H_(2)O_(2)treatment and reaction.Combining DFT calculations,the dynamic evolution of single atomic Cu with nitrogen and oxygen dualcoordination in hydroxylation of benzene is proposed.These findings provide an efficient route to improve the catalytic performance through regulating the coordination environments of SACs and demonstrate a new reaction mechanism in hydroxylation of benzene to phenol reaction.
基金supported by Guizhou Science and Technology Plan Project (LH[2016]7269)the Technical Talent Support Program of Guizhou Education Department (KY[2017]093)+1 种基金Guizhou Provincial Ordinary College Innovation Team ([2014]46)the Doctor Fund Project of Anshun University (Asxybsjj201511)
文摘Two types of ordered mesoporous ZSM-5 zeolites with different mesopores were synthesized by a two-step method. First, carbonaceous SBA- 15 was produced by in situ carbonization of SBA- 15/P 123 composite. Then the obtained SBA- 15/C composite was transformed into crystallized mesoporous ZSM-5 by impregnation TPAOH followed by steam-assisted crystallization. The final calcined samples synthesized with typical SBA-15/P 123 precursor showed a wormlike morphology with the mean mesopore size of 4.6 nm, while samples synthesized with the addition of trimethylbenzene as swelling agent in the precursor exhibited the morphology of microsphere with the mesopore size of about 9.5 nm. Both two types of mesoporous ZSM-5 zeolites exhibited large surface area and mesopore structure. The steam-assisted crystallization (SAC) was performed with lower consumption of solvents. This two-step method may also be suitable for synthesizing other ordered mesoporous zeolites used as catalysts in some catatytic processes.
基金supported by the National Natural Science Foundation of China (21573244, 21573245)the Youth Innovation Promotion Association of Chinese Academy of Sciences (2017049)
文摘Three-dimensional (3D) self-assembled nanomaterials with hierarchical architectures are very attractive materials due to their superior physical and chemical properties [1-7]. Over the past few years, a variety of nanomaterials with well-controlled structures were developed and applied in many areas, including water treatment, energy, sensor and catalysis [8-16].
基金The authors are thankful for the financial support from the National Key Research and Development Program of China(Grant No.2018YFA0208504)National Natural Science Foundation of China(NSFC 21932006)the Youth Innovation Promotion Association of CAS(2017049).
文摘Detection of ppb-level NO_(2) gas under atmosphere is urgent to meet the requirements of the rapidly developing internet of things.Compared with traditional sensing methods,light illumination has been considered as a key approach for excellent gas sensor performance under moderate conditions.Herein,we developed a green-light-assisted gas sensor based on cadmium sulfide nanowires(CdS NWs)that has good NO_(2) sensing capability at ambient temperature.The response values of NO_(2) are 236%and 11%to 10 ppm and 12.5 ppb,respectively.Furthermore,the CdS NWs sensor has a high selectivity for NO_(2) over a variety of interference gases,as well as good stability.The cleaning light activation and the sulfur vacancy-trapped charge behavior of CdS NWs are observed,which suggest a light-assisted sensing mechanism.These results suggest that light-induced charge separation behavior might significantly improve gas-sensing characteristics.