The design and development of low-cost,efficient,and stable bifunctional electrocatalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desirable for rechargeable metal-air batteries.In t...The design and development of low-cost,efficient,and stable bifunctional electrocatalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desirable for rechargeable metal-air batteries.In this work,N-doped porous hollow carbon spheres encapsulated with ultrafine Fe/Fe3O4 nanoparticles(FeOx@N-PHCS)were fabricated by impregnation and subsequent pyrolysis,using melamine-formaldehyde resin spheres as self-sacrifice templates and polydopamine as N and C sources.The sufficient adsorption of Fe3+on the polydopamine endowed the formation of Fe-Nx species upon high-temperature carbonization.The prepared FeOx@N-PHCS has advanced features of large specific surface area,porous hollow structure,high content of N dopants,sufficient Fe-Nx species and ultrafine FeOx nanoparticles.These features endow FeOx@N-PHCS with enhanced mass transfer and considerable active sites,leading to high activity and stability in catalyzing ORR and OER in alkaline electrolyte.Furthermore,the rechargeable Zn-air battery with FeOx@N-PHCS as air cathode catalyst exhibits a large peak power density,narrow charge-discharge potential gap and robust cycling stability,demonstrating the potential of the fabricated FeOx@N-PHCS as a promising electrode material for metal-air batteries.This new finding may open an avenue for rational design of bifunctional catalysts by integrating different active components within all-in-one catalyst for different electrochemical reactions.展开更多
Developing microwave absorption(MA)materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution.In particular,the magnetic component/carbon hybrids absorbers al...Developing microwave absorption(MA)materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution.In particular,the magnetic component/carbon hybrids absorbers always suffer from high filler loading.Herein,we propose a feasible strategy to construct hierarchical porous carbon with tightly embedded Ni nanoparticles(Ni@NPC).These highly dispersed Ni nanoparticles produce strong magnetic coupling networks to enhance magnetic loss abilities.Moreover,the interconnected hierarchical dielectric carbon network affords favorable dipolar/interfacial polarization,conduction loss,multiple reflection and scattering.Impressively,with an ultralow filler loading of 5 wt.%,the resultant Ni@NPC/paraffin composite achieves an excellent MA performance with a minimum reflection loss of as high as-72.4 dB and a broad absorption bandwidth of 5.0 GHz.This capability outperforms most current magnetic-dielectric hybrids counterparts.Furthermore,the MA capacity can be easily tuned with adjustments in thickness,content and type of magnetic material.Thus,this work opens up new avenues for the development of high-performance and lightweight MA materials.展开更多
The exploration of high-efficiency,long-durability,and cost-effectiveness transition metal doped carbon materials to replace the commercial Pt/C in oxygen reduction reaction(ORR)is greatly desirable for promoting the ...The exploration of high-efficiency,long-durability,and cost-effectiveness transition metal doped carbon materials to replace the commercial Pt/C in oxygen reduction reaction(ORR)is greatly desirable for promoting the advancement of sustainable energy devices.Herein,the Fe_(3)N and FeCo alloy decorated N-doped carbon hybrid material(denoted Fe_(3)N-FeCo@NC)is prepared and applied as the ORR catalyst,which is derived from the two-step pyrolysis of an intriguing complex consisted of metal-coordinated porous polydopamine(PDA)nanospheres(i.e.,Fe-PDA@Co)and melamine.The resulting Fe_(3)N-FeCo@NC delivers outstanding ORR activity with an onset potential(E_(on))of 1.05 V,a half-wave potential(E_(1/2))of 0.89 V,as well as excellent long-term stability and methanol resistance over Pt/C.Interestingly,the home-made Zn-air battery with Fe_(3)N-FeCo@NC as the air-cathode demonstrates much higher open-circuit voltage(1.50 vs.1.48 V),power density(141 vs.113 mW·cm^(−2))and specific capacity(806.6 vs.660.6 mAh·g^(−1)_(Zn))than those of Pt/C counterpart.Such a remarkable ORR activity of Fe_(3)N-FeCo@NC may stem from the synergistic effect of Fe_(3)N and FeCo active species,the large surface area,the hierarchical porous structure and the exceptional sphere/sheet hybridized architecture.展开更多
There has been a lot of basic and clinical research on Alzheimer’s disease(AD)over the last 100 years,but its mechanisms and treatments have not been fully clarified.Despite some controversies,the amyloid-beta hypoth...There has been a lot of basic and clinical research on Alzheimer’s disease(AD)over the last 100 years,but its mechanisms and treatments have not been fully clarified.Despite some controversies,the amyloid-beta hypothesis is one of the most widely accepted causes of AD.In this study,we disclose a new amyloid-beta plaque disaggregating agent and an AD brain-targeted delivery system using porous silicon nanoparticles(pSiNPs)as a therapeutic nano-platform to overcome AD.We hypothesized that the negatively charged sulfonic acid functional group could disaggregate plaques and construct a chemical library.As a result of the in vitro assay of amyloid plaques and library screening,we confirmed that 6-amino-2-naphthalenesulfonic acid(ANA)showed the highest efficacy for plaque disaggregation as a hit compound.To confirm the targeted delivery of ANA to the AD brain,a nano-platform was created using porous silicon nanoparticles(pSiNPs)with ANA loaded into the pore of pSiNPs and biotin-polyethylene glycol(PEG)surface functionalization.The resulting nano-formulation,named Biotin-CaCl2-ANA-pSiNPs(BCAP),delivered a large amount of ANA to the AD brain and ameliorated memory impairment of the AD mouse model through the disaggregation of amyloid plaques in the brain.This study presents a new bioactive small molecule for amyloid plaque disaggregation and its promising therapeutic nano-platform for AD brain-targeted delivery.展开更多
Three dimensional(3D)porous nanostructures assembled by low-dimensional nanomaterials are widely applied in gas sensor according to porous structure which can facilitate the transport of gas molecules.In this work,fis...Three dimensional(3D)porous nanostructures assembled by low-dimensional nanomaterials are widely applied in gas sensor according to porous structure which can facilitate the transport of gas molecules.In this work,fish-scale-like porous SnO 2 nanomaterials assembled from ultrathin nanosheets with thick-ness of 16.8 nm were synthesized by a facile hydrothermal route.Then Ag nanoparticles were decorated on the surface of SnO_(2) nanosheets via one-step method to improve their gas-sensing performances.The sensing properties of pristine SnO_(2) and Ag/SnO_(2) nanosheets were investigated intensively.After deco-rating with Ag nanoparticles,the characteristics of SnO_(2) based sensor for triethylamine detection were significantly improved.Especially,the Ag/SnO_(2) based sensor with Ag content of 2 at%exhibited the highest triethylamine sensing sensitivity at optimum work temperature of 170?C.The improved sensing properties of Ag/SnO_(2) sensors were attributed to the sensitizing actions of Ag nanoparticles as well as the unique hierarchical porous architecture.展开更多
An efficient sustainable and scalable strategy for the synthesis of porous cobalt/nitrogen co-doped carbons(Co@NCs) via pyrolysis of aniline-modified ZIFs,has been demonstrated.Aniline can coordinate and absorb on the...An efficient sustainable and scalable strategy for the synthesis of porous cobalt/nitrogen co-doped carbons(Co@NCs) via pyrolysis of aniline-modified ZIFs,has been demonstrated.Aniline can coordinate and absorb on the surface of ZIF(ZIF-CoZn3-PhA),accelerate the precipitation of ZIFs,thus resulting in smaller ZIF particle size.Meanwhile,the aniline on the surface of ZIF-CoZn3-PhA promotes the formation of the protective carbon shell and smaller Co nanoparticles,and increases nitrogen content of the catalyst.Because of these prope rties of Co@NC-PhA-3,the oxidative esterification of 5-hydroxymethylfurfural can be carried out under ambient conditions.According to our experimental and computational results,a synergistic catalytic effect between CoNx sites and Co nanoparticles has been established,in which both Co nanoparticles and CoNx can activate O2 while Co nanoparticles bind and oxidize HMF.Moreover,the formation and release of active oxygen species in CoNx sites are reinfo rced by the electronic interaction between Co nanoparticles and CoNx.展开更多
Owing to the complexity of electron transfer pathways,the sluggish oxygen evolution reaction process is defined as the bottleneck for the practical application of Zn-air batteries.In this effort,metal nanoparticles(Co...Owing to the complexity of electron transfer pathways,the sluggish oxygen evolution reaction process is defined as the bottleneck for the practical application of Zn-air batteries.In this effort,metal nanoparticles(Co,Ni,Fe,etc.)encapsulated within nitrogen-doped carbon materials with abundant edge sites were synthesized by one-step pyrolysis treatment using cigarette butts as raw materials,which can drastically accelerate the overall rate of oxygen evolution reaction by facilitating the adsorption of oxygenated intermediates by the edge-induced topological defects.The prepared catalyst of nitrogen-doped carbon porous nanosheets loaded with Co nanoparticles(Co@NC-500)exhibits enhanced catalytic activity toward oxygen evolution reaction,with a low overpotential of 350 mV at the current density of 10 mA·cm^(-2).Furthermore,the Zn-air battery assembled with Co@NC-500 catalyst demonstrates a desirable performance affording an open-circuit potential of 1.336 V and power density of 33.6 mW·cm^(-2),indicating considerable practical application potential.展开更多
The results of practical implementation of a new method for porous piezoceramics, and ceramic matrix piezocomposites fabrication were presented. The method was based on nanoparticles transport in ceramic matrices usin...The results of practical implementation of a new method for porous piezoceramics, and ceramic matrix piezocomposites fabrication were presented. The method was based on nanoparticles transport in ceramic matrices using a polymer nanogranules coated or filled with a various chemicals, with successive porous ceramics fabrication processes. Different types of polymer microgranules filled and coated by metal-containing nanoparticles were used for a pilot samples fabrication. Polymer microgranules were examined using transmission and scanning electron microscopy as well as by EXAFS and X-ray emission spectroscopy. Pilot samples of nano- and microporous ceramics and composites were fabricated using different piezoceramics compositions (PZT, lead potassium niobate and lead titanate) as a ceramic matrix bases. Resulting ceramic matrix piezocomposites were composed by super lattices of closed or open pores filled or coated by nanoparticles of metals, oxides, ferromagnetics etc. embedded in piezoceramic matrix. Dielectric and piezoelectric parameters of pilot samples were measured using piezoelectric resonance analysis method. New family of nano- and microporous piezoceramics and ceramic matrix piezocomposites are characterized by a unique spectrum of the electrophysical properties unachievable for standard PZT ceramic compositions and fabrication methods.展开更多
A facile EDTA （ethylene diamine tetraacetic acid） complexing technique has been successfully employed to prepare La2Mo2O9 nanoparticles. The as-synthesized products are characterized by X-ray diffraction （XRD）, sc...A facile EDTA （ethylene diamine tetraacetic acid） complexing technique has been successfully employed to prepare La2Mo2O9 nanoparticles. The as-synthesized products are characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and Fourier transform infrared spectroscopy （FT-IR）. The results show that a homogeneous transparent gel can be obtained with EDTA as the organic complexing reagent under the pH value of 3.0. Further thermal decomposition of the as-synthesized transparent gel by increasing the temperature up to 600℃ for 3 h results in the formation of La2Mo2O9 nanoparticles with a crystal size of about 30 nm. Moreover, the nanoparticles tend to form micrometer-sized aggregates with a three-dimensional network structure, which shows promising applications in solid oxide fuel cells （SOFC）, catalysts and so on.展开更多
ZnO nanoparticles and porous particles were produced by an ultrasonic spray pyrolysis method using a zinc nitrate precursor at various temperatures under air atmosphere. The effects of reaction temperature on the size...ZnO nanoparticles and porous particles were produced by an ultrasonic spray pyrolysis method using a zinc nitrate precursor at various temperatures under air atmosphere. The effects of reaction temperature on the size and morphology of ZnO particles were investi- gated. The samples were characterized by energy dispersive spectroscopy, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. ZnO particles were obtained in a hexagonal crystal structure and the crystallite shapes changed from spherical to hex- agonal by elevating the reaction temperature. The crystallite size grew by increasing the temperature, in spite of reducing the residence time in the heated zone. ZnO nanoparticles were obtained at the lowest reaction temperature and ZnO porous particles, formed by aggregation of ZnO nanoparticles due to effective sintering, were prepared at higher temperatures. The results showed that the properties of ZnO particles can be controlled by changing the reaction temperature in the ultrasonic spray pyrolysis method.展开更多
Magnesium hydride(MgH2) is one of the most promising hydrogen storage materials for practical application due to its favorable reversibility, low cost and environmental benign;however, it suffers from high dehydrogena...Magnesium hydride(MgH2) is one of the most promising hydrogen storage materials for practical application due to its favorable reversibility, low cost and environmental benign;however, it suffers from high dehydrogenation temperature and slow sorption kinetics.Exploring proper catalysts with high and sustainable activity is extremely desired for substantially improving the hydrogen storage properties of MgH2. In this work, a composite catalyst with high-loading of ultrafine Ni nanoparticles(NPs) uniformly dispersed on porous hollow carbon nanospheres is developed, which shows superior catalytic activity towards the de-/hydrogenation of MgH2. With an addition of 5wt% of the composite, which contains 90 wt% Ni NPs, the onset and peak dehydrogenation temperatures of MgH2are lowered to 190 and 242 ℃, respectively. 6.2 wt% H2is rapidly released within 30 min at 250 ℃. The amount of H2that the dehydrogenation product can absorb at a low temperature of 150 ℃ in only 250 s is very close to the initial dehydrogenation value. A dehydrogenation capacity of 6.4wt% remains after 50 cycles at a moderate cyclic regime, corresponding to a capacity retention of 94.1%. The Ni NPs are highly active,reacting with MgH2and forming nanosized Mg2Ni/Mg2NiH4. They act as catalysts during hydrogen sorption cycling, and maintain a high dispersibility with the help of the dispersive role of the carbon substrate, leading to sustainably catalytic activity. The present work provides new insight into designing stable and highly active catalysts for promoting the(de)hydrogenation kinetics of MgH2.展开更多
Two flexible click-based porous organic polymers （CPP-F1 and CPP-F2） have been readily synthesized. SEM images show CPP-F1 is a 3D network, while CPP-F2 exhibits a granular morphology. Pd（OAc）2 can be easily incor...Two flexible click-based porous organic polymers （CPP-F1 and CPP-F2） have been readily synthesized. SEM images show CPP-F1 is a 3D network, while CPP-F2 exhibits a granular morphology. Pd（OAc）2 can be easily incorporated into CPP-F1 and CPP-F2 to form Pd@CPP-F1 and Pd@CPP-F2, respectively. The interactions between the polymers and palladium are confirmed by solid-state 13C NMR, IR and XPS. Palladium nanoparticles （NPs） are formed after hydrogenation of olefins and nitrobenzene. Palladium NPs in CPP-F1 are well dispersed on the external surface of the polymer, while palladium NPs in CPP-F2 are located in the interior pores and on the external surface. In comparison with NPs in CPP-F1, the dual distribution of palladium NPs in CPP-F2 results in higher selectivity in the hydrogenation of 1,3-cyclohexadiene to cyclohexane. The catalytic systems can be recycled several times without obvious loss of catalytic activity or agglomeration of palladium NPs. Hot filtration, mercury drop tests and ICP analyses suggest that the catalytic systems proceed via a heterogeneous pathway.展开更多
Photoluminescence （PL） conversion of Si nanoparticles by absorbing ultraviolet （UV） lights and emitting visible ones has been used to improve the efficiency of crystalline Si solar cells. Si nanoparticle thin film...Photoluminescence （PL） conversion of Si nanoparticles by absorbing ultraviolet （UV） lights and emitting visible ones has been used to improve the efficiency of crystalline Si solar cells. Si nanoparticle thin films are prepared by pulverizing porous Si in ethanol and then mixing the suspension with a SiO2 sol-gel （SOG）. This SOG is spin-deposited onto the surface of the Si solar cells and dries in air. The short-circuit current as a function of Si nanoparticle concentration is investigated under UV illumination. The maximal increase is found at a Si concentration of 0.1 mg/mL. At such concentration and under the irradiation of an AM0 solar simulator, the photoelectric conversion efficiency of the crystalline Si solar cell is relatively increased by 2.16% because of the PL conversion.展开更多
基金supported by the National Natural Science Foundation of China(21421001,21573115,21875118)Tianjin Science and Technology Commission(18JCTPJC55900)+1 种基金the Natural Science Foundation of Tianjin(17JCYBJC17100,19JCZDJC37700)the 111 Project(B12015).
文摘The design and development of low-cost,efficient,and stable bifunctional electrocatalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desirable for rechargeable metal-air batteries.In this work,N-doped porous hollow carbon spheres encapsulated with ultrafine Fe/Fe3O4 nanoparticles(FeOx@N-PHCS)were fabricated by impregnation and subsequent pyrolysis,using melamine-formaldehyde resin spheres as self-sacrifice templates and polydopamine as N and C sources.The sufficient adsorption of Fe3+on the polydopamine endowed the formation of Fe-Nx species upon high-temperature carbonization.The prepared FeOx@N-PHCS has advanced features of large specific surface area,porous hollow structure,high content of N dopants,sufficient Fe-Nx species and ultrafine FeOx nanoparticles.These features endow FeOx@N-PHCS with enhanced mass transfer and considerable active sites,leading to high activity and stability in catalyzing ORR and OER in alkaline electrolyte.Furthermore,the rechargeable Zn-air battery with FeOx@N-PHCS as air cathode catalyst exhibits a large peak power density,narrow charge-discharge potential gap and robust cycling stability,demonstrating the potential of the fabricated FeOx@N-PHCS as a promising electrode material for metal-air batteries.This new finding may open an avenue for rational design of bifunctional catalysts by integrating different active components within all-in-one catalyst for different electrochemical reactions.
基金financially supported by the National Natural Science Foundation of China(Nos.21776308 and 21908245)the Science Foundation of China University of Petroleum,Beijing(No.2462018YJRC009)the China Postdoctoral Science Foundation(No.2018T110187)。
文摘Developing microwave absorption(MA)materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution.In particular,the magnetic component/carbon hybrids absorbers always suffer from high filler loading.Herein,we propose a feasible strategy to construct hierarchical porous carbon with tightly embedded Ni nanoparticles(Ni@NPC).These highly dispersed Ni nanoparticles produce strong magnetic coupling networks to enhance magnetic loss abilities.Moreover,the interconnected hierarchical dielectric carbon network affords favorable dipolar/interfacial polarization,conduction loss,multiple reflection and scattering.Impressively,with an ultralow filler loading of 5 wt.%,the resultant Ni@NPC/paraffin composite achieves an excellent MA performance with a minimum reflection loss of as high as-72.4 dB and a broad absorption bandwidth of 5.0 GHz.This capability outperforms most current magnetic-dielectric hybrids counterparts.Furthermore,the MA capacity can be easily tuned with adjustments in thickness,content and type of magnetic material.Thus,this work opens up new avenues for the development of high-performance and lightweight MA materials.
基金upported by the National Natural Science Foundation of China(No.52173207)the Natural Science Foundation of Hunan Province(Nos.2022JJ30563,2020JJ5542)the Outstanding Youth Fund Project of Hunan Provincial Department of Education(No.21B0119).
文摘The exploration of high-efficiency,long-durability,and cost-effectiveness transition metal doped carbon materials to replace the commercial Pt/C in oxygen reduction reaction(ORR)is greatly desirable for promoting the advancement of sustainable energy devices.Herein,the Fe_(3)N and FeCo alloy decorated N-doped carbon hybrid material(denoted Fe_(3)N-FeCo@NC)is prepared and applied as the ORR catalyst,which is derived from the two-step pyrolysis of an intriguing complex consisted of metal-coordinated porous polydopamine(PDA)nanospheres(i.e.,Fe-PDA@Co)and melamine.The resulting Fe_(3)N-FeCo@NC delivers outstanding ORR activity with an onset potential(E_(on))of 1.05 V,a half-wave potential(E_(1/2))of 0.89 V,as well as excellent long-term stability and methanol resistance over Pt/C.Interestingly,the home-made Zn-air battery with Fe_(3)N-FeCo@NC as the air-cathode demonstrates much higher open-circuit voltage(1.50 vs.1.48 V),power density(141 vs.113 mW·cm^(−2))and specific capacity(806.6 vs.660.6 mAh·g^(−1)_(Zn))than those of Pt/C counterpart.Such a remarkable ORR activity of Fe_(3)N-FeCo@NC may stem from the synergistic effect of Fe_(3)N and FeCo active species,the large surface area,the hierarchical porous structure and the exceptional sphere/sheet hybridized architecture.
基金supported by the National Natural Science Foundation of China(Grants 22002121,22172121)the National Undergraduate Training Program for Innovation and Entrepreneurship(Grant S202210656087).
基金supported by Basic Science Research Program through the National Research Foundation(NRF)of Korea funded by the Ministry of Education(2018-R1A6A1A03025124D.K.)+5 种基金supported by Bio&Medical Technology Development Program of the NRF of Korea funded by the Ministry of Science&ICT(2022-M3A9H1014157,2021-M3A9I5030523D.K.)a grant from Korea Health Technology R&D Project of the Korea Health Industry Development Institute(KHIDI)funded by the Ministry of Health&Welfare,Republic of Korea(HI21C0239D.K.)supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(2022-R1F1A1069954D.K.).
文摘There has been a lot of basic and clinical research on Alzheimer’s disease(AD)over the last 100 years,but its mechanisms and treatments have not been fully clarified.Despite some controversies,the amyloid-beta hypothesis is one of the most widely accepted causes of AD.In this study,we disclose a new amyloid-beta plaque disaggregating agent and an AD brain-targeted delivery system using porous silicon nanoparticles(pSiNPs)as a therapeutic nano-platform to overcome AD.We hypothesized that the negatively charged sulfonic acid functional group could disaggregate plaques and construct a chemical library.As a result of the in vitro assay of amyloid plaques and library screening,we confirmed that 6-amino-2-naphthalenesulfonic acid(ANA)showed the highest efficacy for plaque disaggregation as a hit compound.To confirm the targeted delivery of ANA to the AD brain,a nano-platform was created using porous silicon nanoparticles(pSiNPs)with ANA loaded into the pore of pSiNPs and biotin-polyethylene glycol(PEG)surface functionalization.The resulting nano-formulation,named Biotin-CaCl2-ANA-pSiNPs(BCAP),delivered a large amount of ANA to the AD brain and ameliorated memory impairment of the AD mouse model through the disaggregation of amyloid plaques in the brain.This study presents a new bioactive small molecule for amyloid plaque disaggregation and its promising therapeutic nano-platform for AD brain-targeted delivery.
基金This work was supported by the National Natural Science Foundation of China(U1704255)the Key Scientific Research Project of Colleges and University in Henan Province(20A430014,21A430019).
文摘Three dimensional(3D)porous nanostructures assembled by low-dimensional nanomaterials are widely applied in gas sensor according to porous structure which can facilitate the transport of gas molecules.In this work,fish-scale-like porous SnO 2 nanomaterials assembled from ultrathin nanosheets with thick-ness of 16.8 nm were synthesized by a facile hydrothermal route.Then Ag nanoparticles were decorated on the surface of SnO_(2) nanosheets via one-step method to improve their gas-sensing performances.The sensing properties of pristine SnO_(2) and Ag/SnO_(2) nanosheets were investigated intensively.After deco-rating with Ag nanoparticles,the characteristics of SnO_(2) based sensor for triethylamine detection were significantly improved.Especially,the Ag/SnO_(2) based sensor with Ag content of 2 at%exhibited the highest triethylamine sensing sensitivity at optimum work temperature of 170?C.The improved sensing properties of Ag/SnO_(2) sensors were attributed to the sensitizing actions of Ag nanoparticles as well as the unique hierarchical porous architecture.
基金the Fundamental Research Funds for the Central Universities (No.30920021120)Key Laboratory of Biomass Energy and Material,Jiangsu Province (No. JSBEM201912) for financial supporta project funded by the Priority Academic Program development of Jiangsu Higher Education Institution。
文摘An efficient sustainable and scalable strategy for the synthesis of porous cobalt/nitrogen co-doped carbons(Co@NCs) via pyrolysis of aniline-modified ZIFs,has been demonstrated.Aniline can coordinate and absorb on the surface of ZIF(ZIF-CoZn3-PhA),accelerate the precipitation of ZIFs,thus resulting in smaller ZIF particle size.Meanwhile,the aniline on the surface of ZIF-CoZn3-PhA promotes the formation of the protective carbon shell and smaller Co nanoparticles,and increases nitrogen content of the catalyst.Because of these prope rties of Co@NC-PhA-3,the oxidative esterification of 5-hydroxymethylfurfural can be carried out under ambient conditions.According to our experimental and computational results,a synergistic catalytic effect between CoNx sites and Co nanoparticles has been established,in which both Co nanoparticles and CoNx can activate O2 while Co nanoparticles bind and oxidize HMF.Moreover,the formation and release of active oxygen species in CoNx sites are reinfo rced by the electronic interaction between Co nanoparticles and CoNx.
基金the National Natural Science Foundation of China(Grant Nos.22179065,22111530112)the S&T project from Shanghai Tobacco Group Co.Ltd.
文摘Owing to the complexity of electron transfer pathways,the sluggish oxygen evolution reaction process is defined as the bottleneck for the practical application of Zn-air batteries.In this effort,metal nanoparticles(Co,Ni,Fe,etc.)encapsulated within nitrogen-doped carbon materials with abundant edge sites were synthesized by one-step pyrolysis treatment using cigarette butts as raw materials,which can drastically accelerate the overall rate of oxygen evolution reaction by facilitating the adsorption of oxygenated intermediates by the edge-induced topological defects.The prepared catalyst of nitrogen-doped carbon porous nanosheets loaded with Co nanoparticles(Co@NC-500)exhibits enhanced catalytic activity toward oxygen evolution reaction,with a low overpotential of 350 mV at the current density of 10 mA·cm^(-2).Furthermore,the Zn-air battery assembled with Co@NC-500 catalyst demonstrates a desirable performance affording an open-circuit potential of 1.336 V and power density of 33.6 mW·cm^(-2),indicating considerable practical application potential.
文摘The results of practical implementation of a new method for porous piezoceramics, and ceramic matrix piezocomposites fabrication were presented. The method was based on nanoparticles transport in ceramic matrices using a polymer nanogranules coated or filled with a various chemicals, with successive porous ceramics fabrication processes. Different types of polymer microgranules filled and coated by metal-containing nanoparticles were used for a pilot samples fabrication. Polymer microgranules were examined using transmission and scanning electron microscopy as well as by EXAFS and X-ray emission spectroscopy. Pilot samples of nano- and microporous ceramics and composites were fabricated using different piezoceramics compositions (PZT, lead potassium niobate and lead titanate) as a ceramic matrix bases. Resulting ceramic matrix piezocomposites were composed by super lattices of closed or open pores filled or coated by nanoparticles of metals, oxides, ferromagnetics etc. embedded in piezoceramic matrix. Dielectric and piezoelectric parameters of pilot samples were measured using piezoelectric resonance analysis method. New family of nano- and microporous piezoceramics and ceramic matrix piezocomposites are characterized by a unique spectrum of the electrophysical properties unachievable for standard PZT ceramic compositions and fabrication methods.
基金the Opening Subject of the State Key Laboratory of Powder Metallurgy of China (Nos. 200506123105A and 20070620090631B14)
文摘A facile EDTA （ethylene diamine tetraacetic acid） complexing technique has been successfully employed to prepare La2Mo2O9 nanoparticles. The as-synthesized products are characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and Fourier transform infrared spectroscopy （FT-IR）. The results show that a homogeneous transparent gel can be obtained with EDTA as the organic complexing reagent under the pH value of 3.0. Further thermal decomposition of the as-synthesized transparent gel by increasing the temperature up to 600℃ for 3 h results in the formation of La2Mo2O9 nanoparticles with a crystal size of about 30 nm. Moreover, the nanoparticles tend to form micrometer-sized aggregates with a three-dimensional network structure, which shows promising applications in solid oxide fuel cells （SOFC）, catalysts and so on.
基金financially supported by the Scientific and Technological Research Council of Turkey (No. 107M505)
文摘ZnO nanoparticles and porous particles were produced by an ultrasonic spray pyrolysis method using a zinc nitrate precursor at various temperatures under air atmosphere. The effects of reaction temperature on the size and morphology of ZnO particles were investi- gated. The samples were characterized by energy dispersive spectroscopy, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. ZnO particles were obtained in a hexagonal crystal structure and the crystallite shapes changed from spherical to hex- agonal by elevating the reaction temperature. The crystallite size grew by increasing the temperature, in spite of reducing the residence time in the heated zone. ZnO nanoparticles were obtained at the lowest reaction temperature and ZnO porous particles, formed by aggregation of ZnO nanoparticles due to effective sintering, were prepared at higher temperatures. The results showed that the properties of ZnO particles can be controlled by changing the reaction temperature in the ultrasonic spray pyrolysis method.
基金supported by the National Key Research and Development Program of the Ministry of Science and Technology of PR China (No. 2018YFB1502103)National Natural Science Foundation of PR China (Nos. 52071287, 51571175, U1601212, 51831009)。
文摘Magnesium hydride(MgH2) is one of the most promising hydrogen storage materials for practical application due to its favorable reversibility, low cost and environmental benign;however, it suffers from high dehydrogenation temperature and slow sorption kinetics.Exploring proper catalysts with high and sustainable activity is extremely desired for substantially improving the hydrogen storage properties of MgH2. In this work, a composite catalyst with high-loading of ultrafine Ni nanoparticles(NPs) uniformly dispersed on porous hollow carbon nanospheres is developed, which shows superior catalytic activity towards the de-/hydrogenation of MgH2. With an addition of 5wt% of the composite, which contains 90 wt% Ni NPs, the onset and peak dehydrogenation temperatures of MgH2are lowered to 190 and 242 ℃, respectively. 6.2 wt% H2is rapidly released within 30 min at 250 ℃. The amount of H2that the dehydrogenation product can absorb at a low temperature of 150 ℃ in only 250 s is very close to the initial dehydrogenation value. A dehydrogenation capacity of 6.4wt% remains after 50 cycles at a moderate cyclic regime, corresponding to a capacity retention of 94.1%. The Ni NPs are highly active,reacting with MgH2and forming nanosized Mg2Ni/Mg2NiH4. They act as catalysts during hydrogen sorption cycling, and maintain a high dispersibility with the help of the dispersive role of the carbon substrate, leading to sustainably catalytic activity. The present work provides new insight into designing stable and highly active catalysts for promoting the(de)hydrogenation kinetics of MgH2.
文摘Two flexible click-based porous organic polymers （CPP-F1 and CPP-F2） have been readily synthesized. SEM images show CPP-F1 is a 3D network, while CPP-F2 exhibits a granular morphology. Pd（OAc）2 can be easily incorporated into CPP-F1 and CPP-F2 to form Pd@CPP-F1 and Pd@CPP-F2, respectively. The interactions between the polymers and palladium are confirmed by solid-state 13C NMR, IR and XPS. Palladium nanoparticles （NPs） are formed after hydrogenation of olefins and nitrobenzene. Palladium NPs in CPP-F1 are well dispersed on the external surface of the polymer, while palladium NPs in CPP-F2 are located in the interior pores and on the external surface. In comparison with NPs in CPP-F1, the dual distribution of palladium NPs in CPP-F2 results in higher selectivity in the hydrogenation of 1,3-cyclohexadiene to cyclohexane. The catalytic systems can be recycled several times without obvious loss of catalytic activity or agglomeration of palladium NPs. Hot filtration, mercury drop tests and ICP analyses suggest that the catalytic systems proceed via a heterogeneous pathway.
基金supported by the National Basic Research Program of China (No. 2010CB933703)the National Natural Science Foundation of China (No.60878044)
文摘Photoluminescence （PL） conversion of Si nanoparticles by absorbing ultraviolet （UV） lights and emitting visible ones has been used to improve the efficiency of crystalline Si solar cells. Si nanoparticle thin films are prepared by pulverizing porous Si in ethanol and then mixing the suspension with a SiO2 sol-gel （SOG）. This SOG is spin-deposited onto the surface of the Si solar cells and dries in air. The short-circuit current as a function of Si nanoparticle concentration is investigated under UV illumination. The maximal increase is found at a Si concentration of 0.1 mg/mL. At such concentration and under the irradiation of an AM0 solar simulator, the photoelectric conversion efficiency of the crystalline Si solar cell is relatively increased by 2.16% because of the PL conversion.
