This paper presents results of thermoanalytical and structural research on phenolic binder used in foundry for the preparation of moulding sand. The binder has been prepared based on resole type phenolic resin with th...This paper presents results of thermoanalytical and structural research on phenolic binder used in foundry for the preparation of moulding sand. The binder has been prepared based on resole type phenolic resin with the addition of ester hardener. The aim of the study was to determine the structural changes taking place in the phenolic binder under the influence of temperature. Results show that in the investigated range of temperatures, phenolic binder exhibits three exothermic thermal effects accompanying the decomposition process. The test results using the Diffuse Reflectance Infrared Fourier Transform Spectroscopy(DRIFTS) technique show that the addition of a hardener stabilizes the binder structure within methylene bridges. The reduction in the reaction rate observed in the DTA curve at about 330 °C can be associated with the formation of gaseous products by decomposition of the binder or, as suggested by the literature data, the formation of triple bonds and CN-HCN groups.展开更多
The catalytic pyrolysis of lignites is a technical process whose development is complex and time-consuming with the goal to maximize the yield of the desired low-volatile hydrocarbons of choice and to minimize the yie...The catalytic pyrolysis of lignites is a technical process whose development is complex and time-consuming with the goal to maximize the yield of the desired low-volatile hydrocarbons of choice and to minimize the yield of solid residual products. Not every type of lignite is suitable for this process due to its particular chemical composition. In order to be able to predict which lignite specimen will be an especially promising raw material for the pyrolytic liberation of target products, the chemical classification by IR spectroscopic methods was investigated. MIR spectroscopy has been demonstrated to be a valuable tool to characterize the the molecular composition of lignites and to determine the concentrations of aliphatic and aromatic functional groups in lignite as well as alcoholic OH and other forms of bound oxygen. These data provide a comprehensive chemical characterization of the material and help to predict the composition of the chemical components liberated by catalytic decomposition. With a complementary NIR spectroscopic approach, a chemometric method has been developed with which the elemental com-position of the lignites can be determined in a fast and pragmatic way leading to a prediction of the product range of a theoretical pyrolytic product range. Thus, this spectroscopic investigation is a toolbox that can answer the question if the commercial exploitation of catalytic pyrolysis of a lignite sample in question will make sense without preliminary conduction of long and time-consuming testing.展开更多
Pyrrolidine,a five membered heterocyclic molecule,is widely existing in organism.Herein,infrared spectra of pyrrolidine monomer in neutral and cationic states were obtained by vacuum ultraviolet ionization,infrared ph...Pyrrolidine,a five membered heterocyclic molecule,is widely existing in organism.Herein,infrared spectra of pyrrolidine monomer in neutral and cationic states were obtained by vacuum ultraviolet ionization,infrared photodissociation and time of flight mass spectrometry.Both in neutral and cationic states,it is found that their CH stretching vibration bands are red shifted.In the IR spectrum of neutral pyrrolidine,because the electric dipole moment of NH is small,we have not observed the NH stretching vibration bands.However,the NH stretching vibration band of pyrrolidine is greatly enhanced after ionization,and this band red-shifts compared with the previous experiment.The red shifts of CH stretching vibrations in neutral and cationic states are caused by the negative and positive hyperconjugation,respectively.The enhancement and red shift of the NH stretching band are owing to the ejection of the electrons on the N atom after ionization.Through the calculations,it is found that the acidity of the CH bond is a little stronger than that of NH bond.These kinds of studies would be helpful to understand the intrinsic properties of biomolecules in neutral and cationic states,and to provide reference for the further study of living organic macromolecules.展开更多
The present paper discusses the vibrational properties of the mixture gelucire-quercetin(from 1%to 5%)at room and body temperature.Quercetin is a flavonoid having beneficial properties:biological and antioxidant;it is...The present paper discusses the vibrational properties of the mixture gelucire-quercetin(from 1%to 5%)at room and body temperature.Quercetin is a flavonoid having beneficial properties:biological and antioxidant;it is used in many fields as food,cosmetic and especially pharmaceutics but its use as a drug is affected by its low solubility.The Gelucire 50/13 is used as sustained release matrix forming agent in pharmaceutical applications and it has demonstrated the ability to improve the dissolution as well as the absorption of poorly water-soluble drugs.The mixture Gelucire-quercetin was essentially studied by FTIR(Fourier transform infrared spectroscopy)and Raman spectroscopy.The behavior of these two molecules has been investigated in the spectral range 4000-0 cm-1 in Raman spectroscopy,and 4,000-600 cm-1 in FTIR.展开更多
Research on organic solar cells has a craze importance because they show very interesting properties including their flexibility and the opportunity to be made into large surfaces. However, their stability and perform...Research on organic solar cells has a craze importance because they show very interesting properties including their flexibility and the opportunity to be made into large surfaces. However, their stability and performance should be significantly improved compared to their current state. A nominal output of around 10% will be the goal for the coming years. The use of organic materials for photovoltaic applications is the subject of intense research in recent years. This work is based in part on the development of new conjugated polymers. In this paper, we present the synthesis and characterization of poly [(thiophene-2,5-diyl)-co-(benzylidene)] PTB catalysed by Maghnite-H+, used in the active layer of the solar cell organic heterojunction with PCBM (derivative of C60) was used as a junction of the solar cell: Glas/ITO/BCP/C60/PTB/Au/Al. A current density of short circuit of about Jcc 0.1mA/cm2 was obtained for this structure with a yield of around 0.15%.展开更多
Applying the Density Function Theory (DFT) combined with LCAO basis set and employing the B3LYP hybrid functional, the optimized geometrical parameters, electronic properties, as well as the Infrared and Raman spectra...Applying the Density Function Theory (DFT) combined with LCAO basis set and employing the B3LYP hybrid functional, the optimized geometrical parameters, electronic properties, as well as the Infrared and Raman spectra for wurtzite-ZnO structure were investigated. Prior to computing, ZnO thin film prepared by the spray pyrolysis method is characterized by X-ray diffraction using Rietveld refinement. This analysis shows that ZnO has hexagonal wurtzite structure (P6<sub>3</sub>mc) with lattice parameters, a = 3.2467 and c = 5.2151 Åin good agreement with our predicted optimized geometry. Atomic force microscopy (AFM), Raman spectroscopy and UV-Vis-NIR spectrophotometry techniques are used to explore morphological, optical and vibrational properties of the sprayed ZnO thin film. The computed band gap is in excellent agreement with that deduced from UV-Vis transmission . The simulated infrared and Raman spectra were also calculated, and a good agreement with the measured spectra is obtained. Finally, a detailed interpretation of the infrared and Raman spectra is reported.展开更多
A series of poly\|aluminum\|chloride\|sulfate (PACS), which has different basicities (γ) and Al 3+ /SO 2- 4 molar ratio, has been prepared and dried at 105℃ and 65℃, respectively. The distribution of aluminum speci...A series of poly\|aluminum\|chloride\|sulfate (PACS), which has different basicities (γ) and Al 3+ /SO 2- 4 molar ratio, has been prepared and dried at 105℃ and 65℃, respectively. The distribution of aluminum species of PACS was examined, and the effect of γ value, Al 3+ /SO 2- 4 molar ratio, dilution on the distribution of aluminum species of PACS was also investigated by using Al\|ferron timed complex colorimetric method. The IR spectroscopy and X \|ray diffraction were used to study the effect of γ value, Al 3+ /SO 2- 4 molar ratio and the drying temperature on the structure of PACS. The experimental results show that Al 3+ /SO 2- 4 molar ratio has a great effect on the distribution of aluminum species, but the dilution has a little effect on the distribution of aluminum species. The lower the Al 3+ /SO 2- 4 molar ratio, the higher the proportions of the polymer and colloidal species in PACS. The polymeric degree of PACS was related to γ value and Al 3+ /SO 2- 4 molar ratio. Drying temperature has an influence on the structure and the solubility of solid PACS products.展开更多
This work is realized in the context of valorizing natural and local resources, in particular, luffa plant fruit (luffa sponge). The raw fibers of the luffa sponge have a short lifetime. Hence, when they are chemicall...This work is realized in the context of valorizing natural and local resources, in particular, luffa plant fruit (luffa sponge). The raw fibers of the luffa sponge have a short lifetime. Hence, when they are chemically treated, it constitutes a solution is prepared to limit their degradation in the long term and to improve their mechanical characteristics. Therefore, this paper studies the effect of the chemical treatment on the mechanical properties of the luffa sponge’s fibers (fibers of luffa Sponge). The chemical process consists of dipping a brunch of luffa in various concentrations of sodium hydroxide (NaOH) at different time intervals and at different temperature conditions. The luffa sponge’s fibers were mechanical. Characterized before and after the treatment, mechanically (micro traction test). It has been shown that an optimum of 61% increase in mechanical properties (tensile strength) has been reached in the following conditions: treatment with 1% concentration for 90 min at 50°C.展开更多
Cu-based catalyst has been widely used for catalytic reduction of NO.Well-defined TiO_(x)/Cu(110)films were prepared and investi-gated by in situ reflection absorption infrared spectroscopy(IRAS),Auger electron spectr...Cu-based catalyst has been widely used for catalytic reduction of NO.Well-defined TiO_(x)/Cu(110)films were prepared and investi-gated by in situ reflection absorption infrared spectroscopy(IRAS),Auger electron spectroscopy(AES)and low energy electron dif-fraction(LEED).A complex surface structure of Cu^(+)(-O-Ti-)-O-Cu^(δ+)/Cu(110)was proposed,in which the topmost surface Cu+is highly dispersed,isolated and fixed by the TiO_(x) layer.Such a'single atom'-like surface site appears a very narrow vco peak at 2130 cm^(-1),and is more stable upon both CO reduction and vacuum annealing than the Cu_(2)O/Cu(110).Such isolated Cu^(+)(-O-Ti-)site on TiO_(x)/Cu(110)is also fairly stable in NO+CO reaction,but the overall catalytic activity is slightly lower than that on the Cu(110)surface,indicating that the single-atom Cu^(+)(-O-Ti-)site is less efficient for NO+CO reaction at the examined conditions.The study provides useful infor-mation for the design and application of single-atom catalysts and understanding the nature of catalytically active centers.展开更多
Metamaterials have proven their ability to possess extraordinary physical properties distinct from naturally available materials,leading to exciting sensing functionalities and applications.However,metamaterial-based ...Metamaterials have proven their ability to possess extraordinary physical properties distinct from naturally available materials,leading to exciting sensing functionalities and applications.However,metamaterial-based sensing applications suffer from severe performance limitations due to noise interference and design constraints.Here,we propose a dual-phase strategy that leverages loss-induced different Fano-resonant phases to access both destructive and constructive signals of molecular vibration.When the two reverse signals are innovatively combined,the noise in the detection system is effectively suppressed,thereby breaking through the noise-related limitations.Additionally,by utilizing loss optimization of the plasmon-molecule coupling system,our dual-phase strategy enhances the efficiency of infrared energy transfer into the molecule without any additional fabrication complex,thereby overcoming the trade-off dilemma between performance and fabrication cost.Thanks to the pioneering breakthroughs in the limitations,our dual-phase strategy possesses an overwhelming competitive advantage in ultrasensitive vibrational spectroscopy over traditional metamaterial technology,including strong signal strength(×4),high sensitivity(×4.2),effective noise suppression(30%),low detection limit(13 ppm),and excellent selectivity among CO_(2),NH_(3),and CH_(4) mixtures.This work not only opens the door to various emerging ultrasensitive detection applications,including ultrasensitive in-breath diagnostics and high-information analysis of molecular information in dynamic reactions,but also gains new insights into the plasmon-molecule interactions in advanced metamaterials.展开更多
Alkenols are important intermediates for the industrial manufacture of various commodities and fine chemicals.At present,alkenols are produced via thermocatalytic semihydrogenation of corresponding alkynols using prec...Alkenols are important intermediates for the industrial manufacture of various commodities and fine chemicals.At present,alkenols are produced via thermocatalytic semihydrogenation of corresponding alkynols using precious metal Pd-based catalysts in pressurized hydrogen atmosphere.In this work,we highlight an efficient electrocatalytic strategy for selectively reducing alkynols to alkenols under ambient conditions.Using 2-methyl-3-butyn-2-ol as a model alkynol,Cu3P nanoarrays anchored on Cu foam remarkably deliver an industrial-level partial current density of 0.79 A·cm^(-2) and a specific selectivity of 98%for 2-methyl-3-buten-2-ol in acidic solution.Over a 40-runs stability test,Cu3P nanoarrays maintain 90%alkynol conversion and 90%alkenol selectivity.Even in a large two-electrode flow electrolyser,the single-pass alkynol conversion and alkenol selectivity of Cu3P nanoarrays exceed 90%.Moreover,this selective electrocatalytic hydrogenation approach is broadly feasible for the production of various water-soluble alkenols.Electrochemical analyses,theoretical simulation and electrochemical in-situ infrared investigations together reveal that exothermic alkynol hydrogenation,facile alkenol desorption and formation of active H on Cu3P surfaces account for the excellent electrocatalytic performance.展开更多
Liquid fed fuel cells such as direct formic acid fuel cells(DFAFCs)are considered to be promising power sources for portable electronic devices.However,the poison of CO intermediates on the state-of-the-art platinum a...Liquid fed fuel cells such as direct formic acid fuel cells(DFAFCs)are considered to be promising power sources for portable electronic devices.However,the poison of CO intermediates on the state-of-the-art platinum and palladium-based electrocatalysts for the formic acid oxidation reaction(FAOR)at the anode hampers the implementation of DFAFCs technologies.Here,we report a core/shell catalyst consisting of intermetallic PdCd core and Pd shell(i-PdCd@Pd)with promoted CO anti-poison ability and thus FAOR performance.The optimal i-PdCd@Pd catalyst exhibits a high mass activity and specific activity at peak potential,which are 24 and 4 times greater than that of commercial Pd/C catalyst,respectively.We understand by in-situ surface-enhanced infrared absorption spectroscopy(ATR-SEIRA)and X-ray photoelectron spectroscopy(XPS)that in i-PdCd@Pd,the intermetallic PdCd under-layers can induce the downshift of d-band center of surface Pd atoms,which would improve the CO tolerance and thus promote the FAOR performance.展开更多
Unlocking of the extremely inert C=O bond during electrochemical CO_(2) reduction demands subtle regulation on a key“resource”,protons,necessary for intermediate conversion but also readily trapped in water splittin...Unlocking of the extremely inert C=O bond during electrochemical CO_(2) reduction demands subtle regulation on a key“resource”,protons,necessary for intermediate conversion but also readily trapped in water splitting,which is still challenging for developing efficient single-atom catalysts limited by their structural simplicity usually incompetent to handle this task.Incorporation of extra functional units should be viable.Herein,a proton deployment strategy is demonstrated via“atomic and nanostructured iron(A/N-Fe)pairs”,comprising atomically dispersed iron active centers spin-polarized by nanostructured iron carbide ferromagnets,to boost the critical protonation steps.The as-designed catalyst displays a broad window(300 mV)for CO selectivity>90%(98%maximum),even outperforming numerous cutting-edge M–N–C systems.The well-placed control of proton dynamics by A/N-Fe can promote*COOH/*CO formation and simultaneously suppress H2 evolution,benefiting from the magnetic-proximity-induced exchange splitting(spin polarization)that properly adjusts energy levels of the Fe sites’d-shells,and further those of the adsorbed intermediates’antibonding molecular orbitals.展开更多
Two-dimensional nanosheet membranes with responsive nanochannels are appealing for controlled mass transfer/separation,but limited by everchanging thicknesses arising from unstable interfaces.Herein,an interfacially s...Two-dimensional nanosheet membranes with responsive nanochannels are appealing for controlled mass transfer/separation,but limited by everchanging thicknesses arising from unstable interfaces.Herein,an interfacially stable,thermo-responsive nanosheet membrane is assembled from twin-chain stabilized metal-organic framework(MOF)nanosheets,which function via two cyclic amide-bearing polymers,thermo-responsive poly(N-vinyl caprolactam)(PVCL)for adjusting channel size,and non-responsive polyvinylpyrrolidone for supporting constant interlayer distance.Owing to the microporosity of MOF nanosheets and controllable interface wettability,the hybrid membrane demonstrates both superior separation performance and stable thermo-responsiveness.Scattering and correlation spectroscopic analyses further corroborate the respective roles of the two polymers and reveal the microenvironment changes of nanochannels are motivated by the dehydration of PVCL chains.展开更多
文摘This paper presents results of thermoanalytical and structural research on phenolic binder used in foundry for the preparation of moulding sand. The binder has been prepared based on resole type phenolic resin with the addition of ester hardener. The aim of the study was to determine the structural changes taking place in the phenolic binder under the influence of temperature. Results show that in the investigated range of temperatures, phenolic binder exhibits three exothermic thermal effects accompanying the decomposition process. The test results using the Diffuse Reflectance Infrared Fourier Transform Spectroscopy(DRIFTS) technique show that the addition of a hardener stabilizes the binder structure within methylene bridges. The reduction in the reaction rate observed in the DTA curve at about 330 °C can be associated with the formation of gaseous products by decomposition of the binder or, as suggested by the literature data, the formation of triple bonds and CN-HCN groups.
文摘The catalytic pyrolysis of lignites is a technical process whose development is complex and time-consuming with the goal to maximize the yield of the desired low-volatile hydrocarbons of choice and to minimize the yield of solid residual products. Not every type of lignite is suitable for this process due to its particular chemical composition. In order to be able to predict which lignite specimen will be an especially promising raw material for the pyrolytic liberation of target products, the chemical classification by IR spectroscopic methods was investigated. MIR spectroscopy has been demonstrated to be a valuable tool to characterize the the molecular composition of lignites and to determine the concentrations of aliphatic and aromatic functional groups in lignite as well as alcoholic OH and other forms of bound oxygen. These data provide a comprehensive chemical characterization of the material and help to predict the composition of the chemical components liberated by catalytic decomposition. With a complementary NIR spectroscopic approach, a chemometric method has been developed with which the elemental com-position of the lignites can be determined in a fast and pragmatic way leading to a prediction of the product range of a theoretical pyrolytic product range. Thus, this spectroscopic investigation is a toolbox that can answer the question if the commercial exploitation of catalytic pyrolysis of a lignite sample in question will make sense without preliminary conduction of long and time-consuming testing.
基金the National Natural Science Foundation of China(No.U1732146,No.21273083)the Project under Scientific and Technological Planning Grant(No.201805010002)by Guangzhou City.
文摘Pyrrolidine,a five membered heterocyclic molecule,is widely existing in organism.Herein,infrared spectra of pyrrolidine monomer in neutral and cationic states were obtained by vacuum ultraviolet ionization,infrared photodissociation and time of flight mass spectrometry.Both in neutral and cationic states,it is found that their CH stretching vibration bands are red shifted.In the IR spectrum of neutral pyrrolidine,because the electric dipole moment of NH is small,we have not observed the NH stretching vibration bands.However,the NH stretching vibration band of pyrrolidine is greatly enhanced after ionization,and this band red-shifts compared with the previous experiment.The red shifts of CH stretching vibrations in neutral and cationic states are caused by the negative and positive hyperconjugation,respectively.The enhancement and red shift of the NH stretching band are owing to the ejection of the electrons on the N atom after ionization.Through the calculations,it is found that the acidity of the CH bond is a little stronger than that of NH bond.These kinds of studies would be helpful to understand the intrinsic properties of biomolecules in neutral and cationic states,and to provide reference for the further study of living organic macromolecules.
文摘The present paper discusses the vibrational properties of the mixture gelucire-quercetin(from 1%to 5%)at room and body temperature.Quercetin is a flavonoid having beneficial properties:biological and antioxidant;it is used in many fields as food,cosmetic and especially pharmaceutics but its use as a drug is affected by its low solubility.The Gelucire 50/13 is used as sustained release matrix forming agent in pharmaceutical applications and it has demonstrated the ability to improve the dissolution as well as the absorption of poorly water-soluble drugs.The mixture Gelucire-quercetin was essentially studied by FTIR(Fourier transform infrared spectroscopy)and Raman spectroscopy.The behavior of these two molecules has been investigated in the spectral range 4000-0 cm-1 in Raman spectroscopy,and 4,000-600 cm-1 in FTIR.
基金the National Agency for Development and Research of Algeria for the financial support.
文摘Research on organic solar cells has a craze importance because they show very interesting properties including their flexibility and the opportunity to be made into large surfaces. However, their stability and performance should be significantly improved compared to their current state. A nominal output of around 10% will be the goal for the coming years. The use of organic materials for photovoltaic applications is the subject of intense research in recent years. This work is based in part on the development of new conjugated polymers. In this paper, we present the synthesis and characterization of poly [(thiophene-2,5-diyl)-co-(benzylidene)] PTB catalysed by Maghnite-H+, used in the active layer of the solar cell organic heterojunction with PCBM (derivative of C60) was used as a junction of the solar cell: Glas/ITO/BCP/C60/PTB/Au/Al. A current density of short circuit of about Jcc 0.1mA/cm2 was obtained for this structure with a yield of around 0.15%.
文摘Applying the Density Function Theory (DFT) combined with LCAO basis set and employing the B3LYP hybrid functional, the optimized geometrical parameters, electronic properties, as well as the Infrared and Raman spectra for wurtzite-ZnO structure were investigated. Prior to computing, ZnO thin film prepared by the spray pyrolysis method is characterized by X-ray diffraction using Rietveld refinement. This analysis shows that ZnO has hexagonal wurtzite structure (P6<sub>3</sub>mc) with lattice parameters, a = 3.2467 and c = 5.2151 Åin good agreement with our predicted optimized geometry. Atomic force microscopy (AFM), Raman spectroscopy and UV-Vis-NIR spectrophotometry techniques are used to explore morphological, optical and vibrational properties of the sprayed ZnO thin film. The computed band gap is in excellent agreement with that deduced from UV-Vis transmission . The simulated infrared and Raman spectra were also calculated, and a good agreement with the measured spectra is obtained. Finally, a detailed interpretation of the infrared and Raman spectra is reported.
文摘A series of poly\|aluminum\|chloride\|sulfate (PACS), which has different basicities (γ) and Al 3+ /SO 2- 4 molar ratio, has been prepared and dried at 105℃ and 65℃, respectively. The distribution of aluminum species of PACS was examined, and the effect of γ value, Al 3+ /SO 2- 4 molar ratio, dilution on the distribution of aluminum species of PACS was also investigated by using Al\|ferron timed complex colorimetric method. The IR spectroscopy and X \|ray diffraction were used to study the effect of γ value, Al 3+ /SO 2- 4 molar ratio and the drying temperature on the structure of PACS. The experimental results show that Al 3+ /SO 2- 4 molar ratio has a great effect on the distribution of aluminum species, but the dilution has a little effect on the distribution of aluminum species. The lower the Al 3+ /SO 2- 4 molar ratio, the higher the proportions of the polymer and colloidal species in PACS. The polymeric degree of PACS was related to γ value and Al 3+ /SO 2- 4 molar ratio. Drying temperature has an influence on the structure and the solubility of solid PACS products.
文摘This work is realized in the context of valorizing natural and local resources, in particular, luffa plant fruit (luffa sponge). The raw fibers of the luffa sponge have a short lifetime. Hence, when they are chemically treated, it constitutes a solution is prepared to limit their degradation in the long term and to improve their mechanical characteristics. Therefore, this paper studies the effect of the chemical treatment on the mechanical properties of the luffa sponge’s fibers (fibers of luffa Sponge). The chemical process consists of dipping a brunch of luffa in various concentrations of sodium hydroxide (NaOH) at different time intervals and at different temperature conditions. The luffa sponge’s fibers were mechanical. Characterized before and after the treatment, mechanically (micro traction test). It has been shown that an optimum of 61% increase in mechanical properties (tensile strength) has been reached in the following conditions: treatment with 1% concentration for 90 min at 50°C.
基金This work was supported by the National Natural Science Foundation of China(21872110,21327901)the National Key Research and Development Program of China(2020YFB0606401).
文摘Cu-based catalyst has been widely used for catalytic reduction of NO.Well-defined TiO_(x)/Cu(110)films were prepared and investi-gated by in situ reflection absorption infrared spectroscopy(IRAS),Auger electron spectroscopy(AES)and low energy electron dif-fraction(LEED).A complex surface structure of Cu^(+)(-O-Ti-)-O-Cu^(δ+)/Cu(110)was proposed,in which the topmost surface Cu+is highly dispersed,isolated and fixed by the TiO_(x) layer.Such a'single atom'-like surface site appears a very narrow vco peak at 2130 cm^(-1),and is more stable upon both CO reduction and vacuum annealing than the Cu_(2)O/Cu(110).Such isolated Cu^(+)(-O-Ti-)site on TiO_(x)/Cu(110)is also fairly stable in NO+CO reaction,but the overall catalytic activity is slightly lower than that on the Cu(110)surface,indicating that the single-atom Cu^(+)(-O-Ti-)site is less efficient for NO+CO reaction at the examined conditions.The study provides useful infor-mation for the design and application of single-atom catalysts and understanding the nature of catalytically active centers.
基金National Key Research and Development Program of China,Grant/Award Number:2019YFB2004800Advanced Research and Technology Innovation Center(ARTIC)Project,Grant/Award Number:A-0005947-20-00+2 种基金National Natural Science Foundation of China,Grant/Award Number:52072041Ministry of Education(MOE)of Singapore Tier 1 grants,Grant/Award Number:A-0005138-01-00China Postdoctoral Science Foundation,Grant/Award Number:2021M693746。
文摘Metamaterials have proven their ability to possess extraordinary physical properties distinct from naturally available materials,leading to exciting sensing functionalities and applications.However,metamaterial-based sensing applications suffer from severe performance limitations due to noise interference and design constraints.Here,we propose a dual-phase strategy that leverages loss-induced different Fano-resonant phases to access both destructive and constructive signals of molecular vibration.When the two reverse signals are innovatively combined,the noise in the detection system is effectively suppressed,thereby breaking through the noise-related limitations.Additionally,by utilizing loss optimization of the plasmon-molecule coupling system,our dual-phase strategy enhances the efficiency of infrared energy transfer into the molecule without any additional fabrication complex,thereby overcoming the trade-off dilemma between performance and fabrication cost.Thanks to the pioneering breakthroughs in the limitations,our dual-phase strategy possesses an overwhelming competitive advantage in ultrasensitive vibrational spectroscopy over traditional metamaterial technology,including strong signal strength(×4),high sensitivity(×4.2),effective noise suppression(30%),low detection limit(13 ppm),and excellent selectivity among CO_(2),NH_(3),and CH_(4) mixtures.This work not only opens the door to various emerging ultrasensitive detection applications,including ultrasensitive in-breath diagnostics and high-information analysis of molecular information in dynamic reactions,but also gains new insights into the plasmon-molecule interactions in advanced metamaterials.
基金financially supported by the National Natural Science Foundation of China(22005245 and 22201232)the Key Research and Development Program of Shaanxi Province(2023-YBGY-284)+3 种基金the Fundamental Research Funds for the Central Universities(G2022KY0606 and G2022KY05114)the Synergy Innovation Foundation of the University and Enterprise for Graduate Students in Northwestern Polytechnical University(CX2021037 and CX2022074)the Fundamental Research Funds for China Postdoctoral Science Foundation(BX2021247 and 2021M692635)the Natural Science Foundation of Shaanxi Province(2022JQ-083).
文摘Alkenols are important intermediates for the industrial manufacture of various commodities and fine chemicals.At present,alkenols are produced via thermocatalytic semihydrogenation of corresponding alkynols using precious metal Pd-based catalysts in pressurized hydrogen atmosphere.In this work,we highlight an efficient electrocatalytic strategy for selectively reducing alkynols to alkenols under ambient conditions.Using 2-methyl-3-butyn-2-ol as a model alkynol,Cu3P nanoarrays anchored on Cu foam remarkably deliver an industrial-level partial current density of 0.79 A·cm^(-2) and a specific selectivity of 98%for 2-methyl-3-buten-2-ol in acidic solution.Over a 40-runs stability test,Cu3P nanoarrays maintain 90%alkynol conversion and 90%alkenol selectivity.Even in a large two-electrode flow electrolyser,the single-pass alkynol conversion and alkenol selectivity of Cu3P nanoarrays exceed 90%.Moreover,this selective electrocatalytic hydrogenation approach is broadly feasible for the production of various water-soluble alkenols.Electrochemical analyses,theoretical simulation and electrochemical in-situ infrared investigations together reveal that exothermic alkynol hydrogenation,facile alkenol desorption and formation of active H on Cu3P surfaces account for the excellent electrocatalytic performance.
基金support from the National Key Research and Development Program of China(Grant 2018YFA0702001)the National Natural Science Foundation of China(Grant 22071225 and 21603177)+1 种基金the Fundamental Re-search Funds for the Central Universities(Grant WK2060190103)the Joint Funds from Hefei National Synchrotron Radiation Laboratory(Grant KY2060000175).
文摘Liquid fed fuel cells such as direct formic acid fuel cells(DFAFCs)are considered to be promising power sources for portable electronic devices.However,the poison of CO intermediates on the state-of-the-art platinum and palladium-based electrocatalysts for the formic acid oxidation reaction(FAOR)at the anode hampers the implementation of DFAFCs technologies.Here,we report a core/shell catalyst consisting of intermetallic PdCd core and Pd shell(i-PdCd@Pd)with promoted CO anti-poison ability and thus FAOR performance.The optimal i-PdCd@Pd catalyst exhibits a high mass activity and specific activity at peak potential,which are 24 and 4 times greater than that of commercial Pd/C catalyst,respectively.We understand by in-situ surface-enhanced infrared absorption spectroscopy(ATR-SEIRA)and X-ray photoelectron spectroscopy(XPS)that in i-PdCd@Pd,the intermetallic PdCd under-layers can induce the downshift of d-band center of surface Pd atoms,which would improve the CO tolerance and thus promote the FAOR performance.
基金This work was financially supported by National Natural Science Foundation of China(Grant Nos.22075245,21922811,21878270,and 21961160742)Zhejiang Provincial Natural Science Foundation of China(Grant No.LR19B060002)+2 种基金Fundamental Research Funds for the Central Universities(Grant No.2020XZZX002-09)Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(Grant No.2019R01006)Startup Foundation for Hundred-Talent Program of Zhejiang University,Key Laboratory of Marine Materials and Related Technologies,Chinese Academy of Science,and Zhejiang Key Laboratory of Marine Materials and Protective Technologies(2020K10).
文摘Unlocking of the extremely inert C=O bond during electrochemical CO_(2) reduction demands subtle regulation on a key“resource”,protons,necessary for intermediate conversion but also readily trapped in water splitting,which is still challenging for developing efficient single-atom catalysts limited by their structural simplicity usually incompetent to handle this task.Incorporation of extra functional units should be viable.Herein,a proton deployment strategy is demonstrated via“atomic and nanostructured iron(A/N-Fe)pairs”,comprising atomically dispersed iron active centers spin-polarized by nanostructured iron carbide ferromagnets,to boost the critical protonation steps.The as-designed catalyst displays a broad window(300 mV)for CO selectivity>90%(98%maximum),even outperforming numerous cutting-edge M–N–C systems.The well-placed control of proton dynamics by A/N-Fe can promote*COOH/*CO formation and simultaneously suppress H2 evolution,benefiting from the magnetic-proximity-induced exchange splitting(spin polarization)that properly adjusts energy levels of the Fe sites’d-shells,and further those of the adsorbed intermediates’antibonding molecular orbitals.
基金support from the National Natural Science Foundation of China(Nos.21991123,51733003,21674025,and 51873035)“Qimingxing”project(No.19QA1400200)of the Shanghai Committee of Science and Technology.
文摘Two-dimensional nanosheet membranes with responsive nanochannels are appealing for controlled mass transfer/separation,but limited by everchanging thicknesses arising from unstable interfaces.Herein,an interfacially stable,thermo-responsive nanosheet membrane is assembled from twin-chain stabilized metal-organic framework(MOF)nanosheets,which function via two cyclic amide-bearing polymers,thermo-responsive poly(N-vinyl caprolactam)(PVCL)for adjusting channel size,and non-responsive polyvinylpyrrolidone for supporting constant interlayer distance.Owing to the microporosity of MOF nanosheets and controllable interface wettability,the hybrid membrane demonstrates both superior separation performance and stable thermo-responsiveness.Scattering and correlation spectroscopic analyses further corroborate the respective roles of the two polymers and reveal the microenvironment changes of nanochannels are motivated by the dehydration of PVCL chains.
