Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a ...Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol(PVA) concentration on phase change properties were investigated. The thermal properties of microP CMs were characterized by differential scanning calorimetry(DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g^(-1).展开更多
Bromine mediation has been regarded as one of the most efficient ways to activate and convert methane to useful organics.This article reports the effects of active components(Rh,Ru,Pd and Pt)and supports(SiO2,Mg O and...Bromine mediation has been regarded as one of the most efficient ways to activate and convert methane to useful organics.This article reports the effects of active components(Rh,Ru,Pd and Pt)and supports(SiO2,Mg O and Al2O3)on the catalysis of methane oxybromination.Among the prepared catalysts,Rh/SiO2 is the best in performance(CH4 conversion of ca.20%and CH3Br selectivity exceeding 70%).The results reveal that support type has a notable influence on the catalytic performance of Rh,especially on product distribution.The high selectivity to CH3 Br over Rh/SiO2 is attributed to its low propensity for CH3Br oxidation.It was found that Rh small in particle size shows high catalytic activity and CH3Br selectivity.Although silicalite-1 zeolite suffers from a certain degree of structural damage due to the presence of high temperature steam,the use of silicalite-1 as support results in a performance comparable to that of Rh/SiO2.展开更多
Developing a suitable catalyst for the elimination of highly toxic carbonyl sulfide(COS)and hydrogen sulfide(H_(2)S) is of great significance in terms of industrial safety and environmental protection.We demonstrate h...Developing a suitable catalyst for the elimination of highly toxic carbonyl sulfide(COS)and hydrogen sulfide(H_(2)S) is of great significance in terms of industrial safety and environmental protection.We demonstrate here the facile synthesis of graphitized 2D micro-meso-macroporous carbons by one-step carbonization of a mixture of urea and glucose at 700–900℃.The as-synthesized graphitized catalysts,designated as 2DNHPC-x(x=urea/glucose mass ratio),are endowed with an ultra-high concentration(12.9–20.2 wt%)of stable and versatile nitrogen sites(e.g.pyrrole and pyridine)which are anchored on the surface via stable covalent bonding.As a result,the 2D-NHPC-x are active in catalytic hydrolysis of COS on pyrrolic N to H_(2)S,and the H_(2)S can be subsequently captured on pyridinic N and converted to elemental sulfur at ambient conditions over the same materials.Among the prepared catalysts,2D-NHPC-x can catalytically hydrolysize 91%of COS to H_(2)S at 30℃,whereas the conversion ratio over the common catalysts g-C_(3)N_(4)and Fe_(2)O_(3)are below 6.0%.Furthermore,these catalysts also exhibit H_(2)S conversion and sulfur selectivity of nearly 100%at 180℃with long-time durability,which is higher than those of the most reported carbonbased catalysts.In contrast,the H_(2)S capacities of activated carbon,ordered mesoporous carbons(OMC)and N-doped OMC are 3.9,1.5 and2.39 mmol g^(-1),respectively.Both the experimental and theoretical results are disclosed that 2D-NHPC-x are superior to the nitrogen-doped porous materials ever applied in simultaneous catalytic elimination of both COS and H_(2)S.展开更多
Ru-based heterogeneous catalysts have been used in a wide range of important reactions.However,due to the sintering of Ru nanoparticles their practical applications are somewhat restricted.Herein,for the first time we...Ru-based heterogeneous catalysts have been used in a wide range of important reactions.However,due to the sintering of Ru nanoparticles their practical applications are somewhat restricted.Herein,for the first time we report a new and facile strategy to confine Ru and/or Co nanoparticles(NPs) in the channels of N-doped carbon using benzoic acid to guide the deposition location of Ru.The developed catalyst with confined RuCo alloy particles exhibits high resistance against Ru sintering and displays excellent activity and long term stability for NH3 synthesis,achieving an NH3 synthesis rate of up to 18.9 mmol NH_(3) gcat^(-1)h^(-1)at 400℃,which is ca.2.25 times that of the catalyst prepared without confinement(with metal deposited on the support surface).In the latter case,there is an increase of nanoparticle size from 2.52 to 4.25 nm together with ca.48% decrease of NH_(3) synthesis rate after 68 h at 400℃.This study provides a new avenue for simple fabrication of precious-metal-based catalysts that are highly resistant against sintering,specifically suitable for low-temperature synthesis of ammonia with outstanding efficiency.展开更多
This study demonstrated that a Ru-Ni bimetallic core-shell catalyst（0.6%Ru-Ni）@Si O2with a proper surface Ru concentration is superior in achieving better catalytic activity and tunable H2/CO ratio at a comparativel...This study demonstrated that a Ru-Ni bimetallic core-shell catalyst（0.6%Ru-Ni）@Si O2with a proper surface Ru concentration is superior in achieving better catalytic activity and tunable H2/CO ratio at a comparatively lower reaction temperature（700℃）.Compared to the impregnation method,the hydrothermal approach leads to a highly uniform Ru distribution throughout the core particles.Uniform Ru distribution would result in a proper surface Ru concentration as well as more direct Ru-Ni interaction,accounting for better catalyst performance.Enriched surface Ru species hinders surface carbon deposition,but also declines overall activity and H2/CO ratio,meanwhile likely enhances Ni oxidation to certain degree under the applied reaction conditions.Over the current（m%Ru-Ni）@Si O2catalyst,the formation of fibrous carbon species is suppressed,which accounts for good stability of catalyst within a TOS of 10 h.展开更多
All-inorganic halide perovskite(IHP)has been deemed promising in photocatalysis due to tunable bandgap and long lifetime of charge carriers.However,unsatisfactory photocatalytic activity and low stability prevent its ...All-inorganic halide perovskite(IHP)has been deemed promising in photocatalysis due to tunable bandgap and long lifetime of charge carriers.However,unsatisfactory photocatalytic activity and low stability prevent its practical applications.Rational construction of heterojunctions has been proved to be an efficient way to circumvent these obstacles.Herein,g-C_(3)N_(4)nanosheet was employed to construct a 2D/2D(2D:two-dimensional)heterostructure with Cs_(3)Bi_(2)Br_(9)through an electrostatic self-assembly process.Owing to the efficient transfer of photogenerated charge carriers,the activity of Cs_(3)Bi_(2)Br_(9)was boosted with enhanced generation of carbon centered radicals.The optimized 10%Cs_(3)Bi_(2)Br_(9)/g-C_(3)N_(4)composite displays the highest benzaldehyde formation rate of 4.53 mmol·h^(−1)·g^(−1)under visible light,which is 41.8 and 2.3 times that of individual g-C_(3)N_(4)and Cs_(3)Bi_(2)Br_(9),respectively.The stability of Cs_(3)Bi_(2)Br_(9)nanosheets and its selectivity for benzaldehyde(from 65%of Cs_(3)Bi_(2)Br_(9)to 90%of the composite)was enhanced by reducing its surface energy and tuning the reaction pathway,respectively.展开更多
Herein,we describe a simple and efficient method to build C@MoSe_(2)@CNT composites that exhibit good electrochemical performance as anode materials for sodium-ion batteries.The protocol uses commercially available an...Herein,we describe a simple and efficient method to build C@MoSe_(2)@CNT composites that exhibit good electrochemical performance as anode materials for sodium-ion batteries.The protocol uses commercially available and cheap carbon nanotubes(CNT)as the conductive network.Molybdenum selenide(MoSe_(2)),in-situ-synthesized from Mo-ethylene glycol(poly(ethylene glycol)(PEG,M_(n)≈200))complexes,grows along the CNT with a discontinuous morphology,which creates multiple channels for the insertion of Na^(+).Meanwhile,PEG-C provides a thin carbon coating layer to increase stability.For PEG-200-2-C/MoSe_(2)/CNTat room temperature,the storage at 2 A g^(-1)is 426 m A h g^(-1)after 500 cycles and 212 m A h g^(-1)after 3,000 cycles.Compared with pure MoSe_(2),density functional theory calculations indicate that the Na^(+)diffusion barrier in the MoSe_(2)of C@MoSe_(2)@CNT effectively decreases from 0.91 to 0.72 e V,hence promoting the reversibility of the Na^(+)storage.展开更多
Ammonia(NH3)is mainly produced via the Haber-Bosch process.It was discovered that the performance of a wide variety of catalysts in NH3 synthesis could be considerably enhanced by the addition of rare earth elements(R...Ammonia(NH3)is mainly produced via the Haber-Bosch process.It was discovered that the performance of a wide variety of catalysts in NH3 synthesis could be considerably enhanced by the addition of rare earth elements(REEs).As a result,catalysts promoted by REEs,especially the Ru-based ones have been extensively investigated.In this review,we summarize the progress of utilizing REEs for ammonia synthesis and outline the prospects of using them in the design and development of highly efficient and stable catalysts for ammonia synthesis.展开更多
Low-temperature selective catalytic reduction(SCR)is important for the elimination of NOfrom stationary sources.In the present study,the loading of Ce and W onα-Fe_(2)O_(3)was achieved through the integration of sing...Low-temperature selective catalytic reduction(SCR)is important for the elimination of NOfrom stationary sources.In the present study,the loading of Ce and W onα-Fe_(2)O_(3)was achieved through the integration of single-mode microwave and incipient wetness impregnation(IWI)methods.The scanning electron microscopy(SEM)and transmission electron microscopy(TEM)images reveal that the structure ofα-Fe_(2)O_(3)is spindle-like,and the structure remains unchanged after the introduction of Ce and/or W.The results of NH-SCR investigation demonstrate that NOconversion over Ce-W/α-Fe_(2)O_(3)is more than85%at 300℃,which is much higher than that over Ce/a-Fe_(2)O_(3)andα-Fe_(2)O_(3),Our studies illustrate that the addition of Ce can significantly increase the amount of surface oxygen vacancies as well as sites of moderate basicity.On the other hand,the addition of W can obviously decrease the amount of basic sites and increase the number of Br?nsted acid sites.The synergistic effect of Ce and W addition on balancing acidity/basicity properties accounts for the high activity of CeW/α-Fe_(2)O_(3)for NOremoval at low temperatures.The study provides insight into the relationship between acidity/basicity properties and catalytic performance of Ce-W/α-Fe_(2)O_(3)catalysts,which is beneficial to the design of high-performance NH-SCR catalyst for NOremoval at low temperatures.展开更多
In order to achieve high-efficiency conversion of CO_(2) into valuable chemicals,and to exploit new applications of organobismuth compounds,cationic organobismuth complex with 5,6,7,12-tetrahydrodibenz[c,f][1,5]azabis...In order to achieve high-efficiency conversion of CO_(2) into valuable chemicals,and to exploit new applications of organobismuth compounds,cationic organobismuth complex with 5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocine framework was examined for the first time for the coupling of CO_(2) into cyclic carbonates,using terminal epoxides as substrates and tetrabutylammonium halide as co-catalyst in a solvent-free environment under mild conditions.It is shown that the catalyst exhibited high activity and selectivity for the coupling reaction of CO_(2) with a wide range of terminal epoxide.The selectivity of propylene carbonates could reach 100%,and the maximum turnover frequency was up to 10740 h^(-1) at 120℃ and 3 MPa CO_(2) pressure when tetrabutylammonium iodide was used as co-catalyst.Moreover,the catalyst is environment friendly,resistant to air and water,and can be readily reused and recycled without any loss of activity,demonstrating a potential in industrial application.展开更多
基金Supported by the National Natural Science Foundation of China(21476065)the China National Tobacco Corporation
文摘Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol(PVA) concentration on phase change properties were investigated. The thermal properties of microP CMs were characterized by differential scanning calorimetry(DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g^(-1).
基金financially supported by the National Natural Science Foundation of China(Nos.21725602,21776064,21671062 and 21476065)the Innovative Research Groups of Hunan Province(2019JJ10001)。
文摘Bromine mediation has been regarded as one of the most efficient ways to activate and convert methane to useful organics.This article reports the effects of active components(Rh,Ru,Pd and Pt)and supports(SiO2,Mg O and Al2O3)on the catalysis of methane oxybromination.Among the prepared catalysts,Rh/SiO2 is the best in performance(CH4 conversion of ca.20%and CH3Br selectivity exceeding 70%).The results reveal that support type has a notable influence on the catalytic performance of Rh,especially on product distribution.The high selectivity to CH3 Br over Rh/SiO2 is attributed to its low propensity for CH3Br oxidation.It was found that Rh small in particle size shows high catalytic activity and CH3Br selectivity.Although silicalite-1 zeolite suffers from a certain degree of structural damage due to the presence of high temperature steam,the use of silicalite-1 as support results in a performance comparable to that of Rh/SiO2.
基金supported by the National Natural Science Foundation of China(22022804,21978052)the Natural Science Foundation for the Distinguished Young Scholar of Fujian Province(2020J06037)the National Key Research and Development Program of China(2018YFA0209304)。
文摘Developing a suitable catalyst for the elimination of highly toxic carbonyl sulfide(COS)and hydrogen sulfide(H_(2)S) is of great significance in terms of industrial safety and environmental protection.We demonstrate here the facile synthesis of graphitized 2D micro-meso-macroporous carbons by one-step carbonization of a mixture of urea and glucose at 700–900℃.The as-synthesized graphitized catalysts,designated as 2DNHPC-x(x=urea/glucose mass ratio),are endowed with an ultra-high concentration(12.9–20.2 wt%)of stable and versatile nitrogen sites(e.g.pyrrole and pyridine)which are anchored on the surface via stable covalent bonding.As a result,the 2D-NHPC-x are active in catalytic hydrolysis of COS on pyrrolic N to H_(2)S,and the H_(2)S can be subsequently captured on pyridinic N and converted to elemental sulfur at ambient conditions over the same materials.Among the prepared catalysts,2D-NHPC-x can catalytically hydrolysize 91%of COS to H_(2)S at 30℃,whereas the conversion ratio over the common catalysts g-C_(3)N_(4)and Fe_(2)O_(3)are below 6.0%.Furthermore,these catalysts also exhibit H_(2)S conversion and sulfur selectivity of nearly 100%at 180℃with long-time durability,which is higher than those of the most reported carbonbased catalysts.In contrast,the H_(2)S capacities of activated carbon,ordered mesoporous carbons(OMC)and N-doped OMC are 3.9,1.5 and2.39 mmol g^(-1),respectively.Both the experimental and theoretical results are disclosed that 2D-NHPC-x are superior to the nitrogen-doped porous materials ever applied in simultaneous catalytic elimination of both COS and H_(2)S.
基金supported by the National Science Fund for Distinguished Young Scholars of China(21825801)the National Natural Science Foundation of China(21972019)Fujian Outstanding Youth Fund(2019J06011)。
文摘Ru-based heterogeneous catalysts have been used in a wide range of important reactions.However,due to the sintering of Ru nanoparticles their practical applications are somewhat restricted.Herein,for the first time we report a new and facile strategy to confine Ru and/or Co nanoparticles(NPs) in the channels of N-doped carbon using benzoic acid to guide the deposition location of Ru.The developed catalyst with confined RuCo alloy particles exhibits high resistance against Ru sintering and displays excellent activity and long term stability for NH3 synthesis,achieving an NH3 synthesis rate of up to 18.9 mmol NH_(3) gcat^(-1)h^(-1)at 400℃,which is ca.2.25 times that of the catalyst prepared without confinement(with metal deposited on the support surface).In the latter case,there is an increase of nanoparticle size from 2.52 to 4.25 nm together with ca.48% decrease of NH_(3) synthesis rate after 68 h at 400℃.This study provides a new avenue for simple fabrication of precious-metal-based catalysts that are highly resistant against sintering,specifically suitable for low-temperature synthesis of ammonia with outstanding efficiency.
基金the financial support from NSFC (21173118, 21373110)MSTC (2013AA031703)
文摘This study demonstrated that a Ru-Ni bimetallic core-shell catalyst（0.6%Ru-Ni）@Si O2with a proper surface Ru concentration is superior in achieving better catalytic activity and tunable H2/CO ratio at a comparatively lower reaction temperature（700℃）.Compared to the impregnation method,the hydrothermal approach leads to a highly uniform Ru distribution throughout the core particles.Uniform Ru distribution would result in a proper surface Ru concentration as well as more direct Ru-Ni interaction,accounting for better catalyst performance.Enriched surface Ru species hinders surface carbon deposition,but also declines overall activity and H2/CO ratio,meanwhile likely enhances Ni oxidation to certain degree under the applied reaction conditions.Over the current（m%Ru-Ni）@Si O2catalyst,the formation of fibrous carbon species is suppressed,which accounts for good stability of catalyst within a TOS of 10 h.
基金the National Natural Science Foundation of China(Nos.21938002,21725602,21776064,and 21975069)the Innovative Research Groups of Hunan Province(No.2019JJ10001)+1 种基金Science and Technology Planning Project of Hunan Province(No.2019RS3010)C.T.Au thanks HNU for an adjunct professorship.
文摘All-inorganic halide perovskite(IHP)has been deemed promising in photocatalysis due to tunable bandgap and long lifetime of charge carriers.However,unsatisfactory photocatalytic activity and low stability prevent its practical applications.Rational construction of heterojunctions has been proved to be an efficient way to circumvent these obstacles.Herein,g-C_(3)N_(4)nanosheet was employed to construct a 2D/2D(2D:two-dimensional)heterostructure with Cs_(3)Bi_(2)Br_(9)through an electrostatic self-assembly process.Owing to the efficient transfer of photogenerated charge carriers,the activity of Cs_(3)Bi_(2)Br_(9)was boosted with enhanced generation of carbon centered radicals.The optimized 10%Cs_(3)Bi_(2)Br_(9)/g-C_(3)N_(4)composite displays the highest benzaldehyde formation rate of 4.53 mmol·h^(−1)·g^(−1)under visible light,which is 41.8 and 2.3 times that of individual g-C_(3)N_(4)and Cs_(3)Bi_(2)Br_(9),respectively.The stability of Cs_(3)Bi_(2)Br_(9)nanosheets and its selectivity for benzaldehyde(from 65%of Cs_(3)Bi_(2)Br_(9)to 90%of the composite)was enhanced by reducing its surface energy and tuning the reaction pathway,respectively.
基金supported by the National Natural Science Foundation of China(21725602,21878071,21971060)。
文摘Herein,we describe a simple and efficient method to build C@MoSe_(2)@CNT composites that exhibit good electrochemical performance as anode materials for sodium-ion batteries.The protocol uses commercially available and cheap carbon nanotubes(CNT)as the conductive network.Molybdenum selenide(MoSe_(2)),in-situ-synthesized from Mo-ethylene glycol(poly(ethylene glycol)(PEG,M_(n)≈200))complexes,grows along the CNT with a discontinuous morphology,which creates multiple channels for the insertion of Na^(+).Meanwhile,PEG-C provides a thin carbon coating layer to increase stability.For PEG-200-2-C/MoSe_(2)/CNTat room temperature,the storage at 2 A g^(-1)is 426 m A h g^(-1)after 500 cycles and 212 m A h g^(-1)after 3,000 cycles.Compared with pure MoSe_(2),density functional theory calculations indicate that the Na^(+)diffusion barrier in the MoSe_(2)of C@MoSe_(2)@CNT effectively decreases from 0.91 to 0.72 e V,hence promoting the reversibility of the Na^(+)storage.
基金supported by the National Science Fund for Distinguished Young Scholars of China(21825801)the National Natural Science Foundation of China(21972019,21978051).
基金Project supported by the National Natural Science Foundation of China(22038002,21972019)。
文摘Ammonia(NH3)is mainly produced via the Haber-Bosch process.It was discovered that the performance of a wide variety of catalysts in NH3 synthesis could be considerably enhanced by the addition of rare earth elements(REEs).As a result,catalysts promoted by REEs,especially the Ru-based ones have been extensively investigated.In this review,we summarize the progress of utilizing REEs for ammonia synthesis and outline the prospects of using them in the design and development of highly efficient and stable catalysts for ammonia synthesis.
基金Project supported by the National Natural Science Foundation of China(21703037,22108037)the Natural Science Foundation of Fujian(2018J10691)。
文摘Low-temperature selective catalytic reduction(SCR)is important for the elimination of NOfrom stationary sources.In the present study,the loading of Ce and W onα-Fe_(2)O_(3)was achieved through the integration of single-mode microwave and incipient wetness impregnation(IWI)methods.The scanning electron microscopy(SEM)and transmission electron microscopy(TEM)images reveal that the structure ofα-Fe_(2)O_(3)is spindle-like,and the structure remains unchanged after the introduction of Ce and/or W.The results of NH-SCR investigation demonstrate that NOconversion over Ce-W/α-Fe_(2)O_(3)is more than85%at 300℃,which is much higher than that over Ce/a-Fe_(2)O_(3)andα-Fe_(2)O_(3),Our studies illustrate that the addition of Ce can significantly increase the amount of surface oxygen vacancies as well as sites of moderate basicity.On the other hand,the addition of W can obviously decrease the amount of basic sites and increase the number of Br?nsted acid sites.The synergistic effect of Ce and W addition on balancing acidity/basicity properties accounts for the high activity of CeW/α-Fe_(2)O_(3)for NOremoval at low temperatures.The study provides insight into the relationship between acidity/basicity properties and catalytic performance of Ce-W/α-Fe_(2)O_(3)catalysts,which is beneficial to the design of high-performance NH-SCR catalyst for NOremoval at low temperatures.
基金This work was supported by the National Natural Science Foundation of China(Grant No.20507005)Outstanding Young Research Award of National Natural Science Foundation of China(Grant No.E50725825).
文摘In order to achieve high-efficiency conversion of CO_(2) into valuable chemicals,and to exploit new applications of organobismuth compounds,cationic organobismuth complex with 5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocine framework was examined for the first time for the coupling of CO_(2) into cyclic carbonates,using terminal epoxides as substrates and tetrabutylammonium halide as co-catalyst in a solvent-free environment under mild conditions.It is shown that the catalyst exhibited high activity and selectivity for the coupling reaction of CO_(2) with a wide range of terminal epoxide.The selectivity of propylene carbonates could reach 100%,and the maximum turnover frequency was up to 10740 h^(-1) at 120℃ and 3 MPa CO_(2) pressure when tetrabutylammonium iodide was used as co-catalyst.Moreover,the catalyst is environment friendly,resistant to air and water,and can be readily reused and recycled without any loss of activity,demonstrating a potential in industrial application.
