Dispersing metals from nanoparticles into clusters or single atoms often exhibits unique properties such as the inhibition of structure-sensitive side reactions.Here,we reported the use of ion exchange(IE)methods and ...Dispersing metals from nanoparticles into clusters or single atoms often exhibits unique properties such as the inhibition of structure-sensitive side reactions.Here,we reported the use of ion exchange(IE)methods and direct hydrogen reduction to achieve high dispersion of Co species on zincosilicate.The obtained 2Co/Zn-4-IE catalyst achieved an initial propane conversion of 41.4%at a temperature of 550℃in a 25%propane and 75%nitrogen atmosphere for propane dehydrogenation.Visualization of the presence of Co species within specific rings(alpha-α,beta-βand delta-δ)was obtained by aberration-corrected scanning transmission electron microscopy.A series of Fourier transform infrared spectra confirmed the anchoring of Co by specific hydroxyl groups in zincosilicate and the specific coordination environment of Co and its presence in the rings essentially as a single site.The framework Zn for the modulation of the microenvironment and the presence of Co species as Lewis acid active sites(Co-O4)was also supported by density functional theory calculations.展开更多
The electrosynthesis of hydrogen peroxide is limited by the competitive four-electron oxygen reduction reaction(ORR)pathway.The modulation for the adsorption of OOH^(*)intermediate on active sites is considered as the...The electrosynthesis of hydrogen peroxide is limited by the competitive four-electron oxygen reduction reaction(ORR)pathway.The modulation for the adsorption of OOH^(*)intermediate on active sites is considered as the effective approach to tune the ORR selectivity,but it remains challenging.Herein,we report the neighboring phosphorus atom in the second coordination shell to regulate the electronic structure of the isolated Ni-N_(4) sites,leading to the favored OOH^(*)adsorption and thus boosting the electrocatalytic ORR to hydrogen peroxide through the two-electron pathway.Spectroscopy characterizations and density functional theory calculations indicate the neighboring phosphorus atom in the second coordination shell triggers the electron transfer to central Ni atom,strengthening the adsorption of OOH^(*)on Ni sites and thus increasing the catalytic performance for two-electron ORR,delivering a selectivity above 90%for production of hydrogen peroxide under the current density of 150 mA·cm^(−2).This work reveals tailoring second coordination shell of isolated metal sites could be as a precise and efficient way to engineer the catalytic performance,which thus provides a promising approach to the design of advanced catalysts.展开更多
Decorating semi-conducting metal oxide with noble metal has been recognized as a viable approach to improve the sensitivity of gas sensor. However, conventional method which relys on noble metal nanoparticles is confr...Decorating semi-conducting metal oxide with noble metal has been recognized as a viable approach to improve the sensitivity of gas sensor. However, conventional method which relys on noble metal nanoparticles is confronted with drawback of significantly increased cost. To maximize the atom efficiency and reduce the cost for practical industrial application, designing sensor material with noble metal isolated single atom sites (ISAS) doping is a desired option. Here, we report an atomically dispersed platinum on one-dimensional arranged porous γ-Fe2O3 nanoparticle composites as highly efficient ethanol gas sensor. The optimized sample (Pt1-Fe2O3-ox) exhibited a high response (Ra/Rg = 102.4) and good selectivity to ethanol gas. It is demonstrated only the Pt single atom sites with high valance can effectively promote the adsorption capacity to ethanol and consequently enhance the sensitivity of sensing process by changing the electrical structure of Fe2O3 support. This work indicates the single atom sites could play a vital role in improving the performance of conventional metal oxides gas sensors and pave way for the exploration of ISAS-enhanced gas sensor for other volatile organic compounds (VOCs).展开更多
Regulating the selectivity of catalysts in selective hydrogenation reactions at the atomic level is highly desirable but remains a grand challenge. Here we report a simple and practical strategy to synthesize a monoli...Regulating the selectivity of catalysts in selective hydrogenation reactions at the atomic level is highly desirable but remains a grand challenge. Here we report a simple and practical strategy to synthesize a monolithic single-atom catalyst(SAC) with isolated Pd atoms supported on bulk nitrogen-doped carbon foams(Pd-SAs/CNF). Moreover, we demonstrate that the single-atom Pd sites with unique electronic structure endow Pd-SAs/CNF with an isolated site effect, leading to excellent activity and selectivity in 4-nitrophenylacetylene semi-hydrogenation reaction. In addition, benefiting from the great integrity and excellent mechanical strength, monolithic Pd-SAs/CNF catalyst is easy to separate from the reaction system for conducting the subsequent recycling. The cyclic test demonstrates the excellent reusability and stability of monolithic Pd-SAs/CNF catalyst.The discovery of isolated site effect provides a new approach to design highly selective catalysts. And the development of monolithic SACs provides new opportunities to advance the practical applications of single-atom catalysts.展开更多
Alkene hydroformylation is an extremely important industry process currently accomplished via homogeneous catalysis.Heterogeneous hydroformylation is being avidly pursued as a more economical and sustainable process.H...Alkene hydroformylation is an extremely important industry process currently accomplished via homogeneous catalysis.Heterogeneous hydroformylation is being avidly pursued as a more economical and sustainable process.Herein,we report the construction of zeolite-encaged rhodium catalyst for efficient hydroformylation.Through a facile in situ hydrothermal strategy,isolated Rh^(δ+)(δ=2.5)can be encaged in faujasite and efficiently stabilized via interaction with framework oxygen atoms,producing a Rh@Y model catalyst with well-defined rhodium sites and coordination environment.Rh@Y exhibits high catalytic activity,perfect chemoselectivity,and recyclability in 1-hexene hydroformylation under mild reaction conditions,making it a robust heterogeneous catalyst for potential applications.A state-of-the-art turnover frequency value of 6567 molC=C/molRh/h for Rh@Y can be achieved in 1-hexene hydroformylation at 393 K,outperforming all heterogeneous catalysts and most homogeneous catalysts under comparable conditions.With the well-defined structure of Rh@Y,the detailed mechanism of alkene hydroformylation can be interpreted via theoretical calculations,and the advantages of heterogeneous hydroformylation are well explained.This work provides a promising solution toward efficient heterogeneous noble metal catalysis by encaging stable isolated ions in a zeolite matrix.展开更多
In most isolated sites situated in south Algeria, the diesel generators are the major source of electrical energy. Indeed, the power supply of these remote regions still poses order problems （technical, economical an...In most isolated sites situated in south Algeria, the diesel generators are the major source of electrical energy. Indeed, the power supply of these remote regions still poses order problems （technical, economical and ecological）. The electricity produced with the help of diesel generators is very expensive and responsible for CO2 emission. These isolated sites have significant wind energy potential. Hence, the use of twinning wind-diesel is widely recommended, especially to reduce operating deficits. The objective of this paper is to study the global modeling of a hybrid system which compounds wind turbine generator, diesel generator and storage system. This model is based on the control strategy to optimize the functioning of the hybrid system and to consolidate the gains to provide proper management of energy sources （wind, diesel, battery） depending on the load curve of the proposed site. The management is controlled by a controller which ensures the opening/closing of different power switches according to meteorological conditions （wind speed, air mass, temperature, etc）.展开更多
文摘Dispersing metals from nanoparticles into clusters or single atoms often exhibits unique properties such as the inhibition of structure-sensitive side reactions.Here,we reported the use of ion exchange(IE)methods and direct hydrogen reduction to achieve high dispersion of Co species on zincosilicate.The obtained 2Co/Zn-4-IE catalyst achieved an initial propane conversion of 41.4%at a temperature of 550℃in a 25%propane and 75%nitrogen atmosphere for propane dehydrogenation.Visualization of the presence of Co species within specific rings(alpha-α,beta-βand delta-δ)was obtained by aberration-corrected scanning transmission electron microscopy.A series of Fourier transform infrared spectra confirmed the anchoring of Co by specific hydroxyl groups in zincosilicate and the specific coordination environment of Co and its presence in the rings essentially as a single site.The framework Zn for the modulation of the microenvironment and the presence of Co species as Lewis acid active sites(Co-O4)was also supported by density functional theory calculations.
基金financially supported by the Taishan Scholar Project Foundation of Shandong Province(Nos.tsqn202211028 and tsqn202306080)the Natural Science Foundation of Shandong Province(Nos.ZR2022JQ08 and 2023HWYQ-028)the Instrument Improvement Founds of Shandong University Public Technology Platform(No.ts20230209).
文摘The electrosynthesis of hydrogen peroxide is limited by the competitive four-electron oxygen reduction reaction(ORR)pathway.The modulation for the adsorption of OOH^(*)intermediate on active sites is considered as the effective approach to tune the ORR selectivity,but it remains challenging.Herein,we report the neighboring phosphorus atom in the second coordination shell to regulate the electronic structure of the isolated Ni-N_(4) sites,leading to the favored OOH^(*)adsorption and thus boosting the electrocatalytic ORR to hydrogen peroxide through the two-electron pathway.Spectroscopy characterizations and density functional theory calculations indicate the neighboring phosphorus atom in the second coordination shell triggers the electron transfer to central Ni atom,strengthening the adsorption of OOH^(*)on Ni sites and thus increasing the catalytic performance for two-electron ORR,delivering a selectivity above 90%for production of hydrogen peroxide under the current density of 150 mA·cm^(−2).This work reveals tailoring second coordination shell of isolated metal sites could be as a precise and efficient way to engineer the catalytic performance,which thus provides a promising approach to the design of advanced catalysts.
基金This work was supported by the National Key R&D Program of China(No.2018YFA0702003)the National Natural Science Foundation of China(Nos.21890383 and 21971137)+1 种基金Science and Technology Key Project of Guangdong Province of China(No.2020B010188002)Beijing Municipal Science&Technology Commission(No.Z191100007219003).
文摘Decorating semi-conducting metal oxide with noble metal has been recognized as a viable approach to improve the sensitivity of gas sensor. However, conventional method which relys on noble metal nanoparticles is confronted with drawback of significantly increased cost. To maximize the atom efficiency and reduce the cost for practical industrial application, designing sensor material with noble metal isolated single atom sites (ISAS) doping is a desired option. Here, we report an atomically dispersed platinum on one-dimensional arranged porous γ-Fe2O3 nanoparticle composites as highly efficient ethanol gas sensor. The optimized sample (Pt1-Fe2O3-ox) exhibited a high response (Ra/Rg = 102.4) and good selectivity to ethanol gas. It is demonstrated only the Pt single atom sites with high valance can effectively promote the adsorption capacity to ethanol and consequently enhance the sensitivity of sensing process by changing the electrical structure of Fe2O3 support. This work indicates the single atom sites could play a vital role in improving the performance of conventional metal oxides gas sensors and pave way for the exploration of ISAS-enhanced gas sensor for other volatile organic compounds (VOCs).
基金supported by the National Key R&D Program of China (2018YFA0702003)the National Natural Science Foundation of China (21890383,21671117,21871159 and 21901135)+1 种基金the National Postdoctoral Program for Innovative Talents (BX20180160)the China Postdoctoral Science Foundation (2018M640113)。
文摘Regulating the selectivity of catalysts in selective hydrogenation reactions at the atomic level is highly desirable but remains a grand challenge. Here we report a simple and practical strategy to synthesize a monolithic single-atom catalyst(SAC) with isolated Pd atoms supported on bulk nitrogen-doped carbon foams(Pd-SAs/CNF). Moreover, we demonstrate that the single-atom Pd sites with unique electronic structure endow Pd-SAs/CNF with an isolated site effect, leading to excellent activity and selectivity in 4-nitrophenylacetylene semi-hydrogenation reaction. In addition, benefiting from the great integrity and excellent mechanical strength, monolithic Pd-SAs/CNF catalyst is easy to separate from the reaction system for conducting the subsequent recycling. The cyclic test demonstrates the excellent reusability and stability of monolithic Pd-SAs/CNF catalyst.The discovery of isolated site effect provides a new approach to design highly selective catalysts. And the development of monolithic SACs provides new opportunities to advance the practical applications of single-atom catalysts.
基金This work was supported by the National Natural Science Fund of China(grant nos.21872072 and 22025203)the Frontiers Science Center for New Organic Matter,Nankai University(grant no.63181206)Haihe Laboratory of Sustainable Chemical Transformations,Tianjin.
文摘Alkene hydroformylation is an extremely important industry process currently accomplished via homogeneous catalysis.Heterogeneous hydroformylation is being avidly pursued as a more economical and sustainable process.Herein,we report the construction of zeolite-encaged rhodium catalyst for efficient hydroformylation.Through a facile in situ hydrothermal strategy,isolated Rh^(δ+)(δ=2.5)can be encaged in faujasite and efficiently stabilized via interaction with framework oxygen atoms,producing a Rh@Y model catalyst with well-defined rhodium sites and coordination environment.Rh@Y exhibits high catalytic activity,perfect chemoselectivity,and recyclability in 1-hexene hydroformylation under mild reaction conditions,making it a robust heterogeneous catalyst for potential applications.A state-of-the-art turnover frequency value of 6567 molC=C/molRh/h for Rh@Y can be achieved in 1-hexene hydroformylation at 393 K,outperforming all heterogeneous catalysts and most homogeneous catalysts under comparable conditions.With the well-defined structure of Rh@Y,the detailed mechanism of alkene hydroformylation can be interpreted via theoretical calculations,and the advantages of heterogeneous hydroformylation are well explained.This work provides a promising solution toward efficient heterogeneous noble metal catalysis by encaging stable isolated ions in a zeolite matrix.
文摘In most isolated sites situated in south Algeria, the diesel generators are the major source of electrical energy. Indeed, the power supply of these remote regions still poses order problems （technical, economical and ecological）. The electricity produced with the help of diesel generators is very expensive and responsible for CO2 emission. These isolated sites have significant wind energy potential. Hence, the use of twinning wind-diesel is widely recommended, especially to reduce operating deficits. The objective of this paper is to study the global modeling of a hybrid system which compounds wind turbine generator, diesel generator and storage system. This model is based on the control strategy to optimize the functioning of the hybrid system and to consolidate the gains to provide proper management of energy sources （wind, diesel, battery） depending on the load curve of the proposed site. The management is controlled by a controller which ensures the opening/closing of different power switches according to meteorological conditions （wind speed, air mass, temperature, etc）.
