The composition and evolution of interfacial species play a key role during electrocatalytic process.Unveiling the structural evolution and intermediate during catalytic process by in situ characterization can shed ne...The composition and evolution of interfacial species play a key role during electrocatalytic process.Unveiling the structural evolution and intermediate during catalytic process by in situ characterization can shed new light on the electrocatalytic reaction mechanism and develop highly efficient catalyst.However,directly probing the interfacial species is extremely difficult for most spectroscopic techniques due to complicated interfacial environment and ultra-low surface concentration.Herein,electrochemical core-shell nanoparticle enhanced Raman spectroscopy is utilized to probe the composition and evolution processes of interfacial species on Au@Pt,Au@Co,and Au@PtCo core-shell nanoparticle surfaces.The spectral evidences of interfacial intermediates including hydroxide radical(OH*),superoxide ion(O_(2)^(−)),as well as metal oxide species are directly captured by in situ Raman spectroscopy,which are further confirmed by the both isotopic experiment and density functional theory calculation.These results provide a mechanistic guideline for the rational design of highly efficient electrocatalysts.展开更多
Ni@Pd core-shell nanoparticles with a mean particle size of 8–9 nm were prepared by solvothermal reduction of bivalent nickel and palladium in oleylamine and trioctylphosphine.Subsequently,the first-ever deposition o...Ni@Pd core-shell nanoparticles with a mean particle size of 8–9 nm were prepared by solvothermal reduction of bivalent nickel and palladium in oleylamine and trioctylphosphine.Subsequently,the first-ever deposition of Ni@Pd core-shell nanoparticles having different compositions on a metal-organic framework（MIL-101）was accomplished by wet impregnation in n-hexane.The Ni@Pd/MIL-101 materials were characterized by powder X-ray diffraction,Fourier transform infrared spectroscopy,transmission electron microscopy,and energy-dispersive X-ray spectroscopy and also investigated as catalysts for the hydrogenation of nitrobenzene under mild reaction conditions.At 30 °C and 0.1 MPa of H2 pressure,the Ni@Pd/MIL-101 gives a TOF as high as 375 h–1 for the hydrogenation of nitrobenzene and is applicable to a wide range of substituted nitroarenes.The exceptional performance of this catalyst is believed to result from the significant Ni-Pd interaction in the core-shell structure,together with promotion of the conversions of aromatics by uncoordinated Lewis acidic Cr sites on the MIL-101 support.展开更多
Satisfactory ionic conductivity,excellent mechanical stability,and high-temperature resistance are the prerequisites for the safe application of solid polymer electrolytes(SPEs)in all-solid-state lithium metal batteri...Satisfactory ionic conductivity,excellent mechanical stability,and high-temperature resistance are the prerequisites for the safe application of solid polymer electrolytes(SPEs)in all-solid-state lithium metal batteries(ASSLMBs).In this study,a novel poly(m-phenylene isophthalamide)(PMIA)-core/poly(ethylene oxide)(PEO)-shell nanofiber membrane and the functional Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)ceramic nanopar-ticle are simultaneously introduced into the PEO-based SPEs to prepare composite polymer electrolytes(CPEs).The core PMIA layer of composite nanofibers can greatly improve the mechanical strength and thermal stability of the CPEs,while the shell PEO layer can provide the 3D continuous transport channels for lithium ions.In addition,the introduction of functional LLZTO nanoparticle not only reduces the crys-tallinity of PEO,but also promotes the dissociation of lithium salts and releases more Li^(+)ions through its interaction with the Lewis acid-base of anions,thereby overall improving the transport of lithium ions.Consequently,the optimized CPEs present high ionic conductivity of 1.38×10^(−4)S/cm at 30℃,signifi-cantly improved mechanical strength(8.5 MPa),remarkable thermal stability(without obvious shrinkage at 150℃),and conspicuous Li dendrites blocking ability(>1800 h).The CPEs also both have good com-patibility and cyclic stability with LiFePO_(4)(>2000 cycles)and high-voltage LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811)(>500 cycles)cathodes.In addition,even at low temperature(40℃),the assembled LiFePO4/CPEs/Li bat-tery still can cycle stably.The novel design can provide an effective way to exploit high-performance solid-state electrolytes.展开更多
A simple method to prepare titania nanomaterials of core-shell structure, hollow nanospheres and mesoporous nanoparticles has been developed. The core-shell nanostructures with NH4Cl as core and TiO2·xH2O-NH4Cl a...A simple method to prepare titania nanomaterials of core-shell structure, hollow nanospheres and mesoporous nanoparticles has been developed. The core-shell nanostructures with NH4Cl as core and TiO2·xH2O-NH4Cl as shell were prepared in nonaqueous system by the deposition on the surface of the aggregated NH4Cl crystals, which could be transformed into mesoporous anatase nanoparticles or hollow nanospheres by calcination at 500°C or extraction with methanol, respectively. The hierarchical mesoporous nanostructures benefited the photocatalytic activities of the resultant titania nanomaterials, demonstrated by the UV light photodegradation of Methyl Orange.展开更多
Magnetic core-shell nanoparticles have been widely studied because of their excellent and convenient magnetic and electrical properties.In this present work core-shell magneticnanoparticles (MNPs) were synthesized by ...Magnetic core-shell nanoparticles have been widely studied because of their excellent and convenient magnetic and electrical properties.In this present work core-shell magneticnanoparticles (MNPs) were synthesized by simple chemical precipitation method. Firstly Mg(x)Fe(1–x)O (magnesiwuestite) nano powder samples were synthesised by low temperature chemical combustion method. Secondly the as synthesised Mg(x)Fe(1–x)O nanoparticles are used to synthesis magnetic core-shell Nano particles byusing 2-propanol, poly ethylene glycol (PEG), ammonia solution 30 wt%, tetraethyl orthosilicate (TEOS). Separation of the core-shell magnetic nanoparticles from the aqueous suspension using a centrifuge. The synthesised MNPs and core shell MNP were characterized by X-ray diffraction (XRD), Thermal gravimetric-differential thermal analyzer (TG-DTA), Transmission electron microscopy (TEM), scanning electron microscopy (SEM), (EDAX) for structural, thermal and morphological respectively. It is observed that the particle size of spherical sampleis 32.5 nm.展开更多
The past few years witnessed extensive emergence of short-wavelength upconversion（UC） emission stimulated photoactivation studies. However, low efficiency of multi-photon process greatly limits further applications....The past few years witnessed extensive emergence of short-wavelength upconversion（UC） emission stimulated photoactivation studies. However, low efficiency of multi-photon process greatly limits further applications. Here, ultraviolet（UV） upconversion emissions originated from multi-photon process of Tm^3＋ were studied with Nd^3＋-sensitized NaGdF4：Yb,Tm@NaYF4：Nd,Yb core/shell nanoparticles. Crucial factors, including the contents of sensitizers Nd^3＋, Yb^3＋ and activator Tm^3＋, as well as the excitation power density were investigated based on the UV emission. Spectral results showed that high contents of Nd^3＋ in shell region up to 50%（molar fraction hereafter） and Yb^3＋ of 10% were essential to mediate the energy transfer via the core/shell interface and facilitate multi-photon UV emissions. Compared with segregated activator and sensitizer, a core/shell strategy with isolated Nd^3＋ in the shell was important for higher UV emission. Although the upconverting process was initiated with Nd^3＋→Yb^3＋, the short-wavelength emissions were intrinsically coming from four- and five-photon process. The optimized nanoparticles were found to be able to manipulate the configuration transition of azobenzene molecules, and it could be promising for near infrared（NIR） triggered optical switches applications.展开更多
基金the National Key Research and Development Program of China(No.2020YFB1505800)the National Natural Science Foundation of China(Nos.21925404 and 22021001)+5 种基金the Shenzhen Science and Technology Research Grant(No.JCYJ20200109140416788)the Science and Technology Program of Fujian Province(No.2021Y01010295)the Youth Talent Support Program of Fujian Province(Eyas Plan of Fujian Province 2021)Research Initiation Fund of Jimei University(No.ZQ2021008)the Natural Science Foundation of Fujian Province of China(No.2021J06001)the China Postdoctoral Science Foundation(Nos.2021TQ0188 and 2021M691874).
文摘The composition and evolution of interfacial species play a key role during electrocatalytic process.Unveiling the structural evolution and intermediate during catalytic process by in situ characterization can shed new light on the electrocatalytic reaction mechanism and develop highly efficient catalyst.However,directly probing the interfacial species is extremely difficult for most spectroscopic techniques due to complicated interfacial environment and ultra-low surface concentration.Herein,electrochemical core-shell nanoparticle enhanced Raman spectroscopy is utilized to probe the composition and evolution processes of interfacial species on Au@Pt,Au@Co,and Au@PtCo core-shell nanoparticle surfaces.The spectral evidences of interfacial intermediates including hydroxide radical(OH*),superoxide ion(O_(2)^(−)),as well as metal oxide species are directly captured by in situ Raman spectroscopy,which are further confirmed by the both isotopic experiment and density functional theory calculation.These results provide a mechanistic guideline for the rational design of highly efficient electrocatalysts.
基金supported by the National Natural Science Foundation of China(21322606 and 21436005)the Specialized Research Fund for the Doctoral Program of Higher Education(20120172110012)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Natural Science Foundation of Guangdong Province(S2011020002397 and 2013B090500027)~~
文摘Ni@Pd core-shell nanoparticles with a mean particle size of 8–9 nm were prepared by solvothermal reduction of bivalent nickel and palladium in oleylamine and trioctylphosphine.Subsequently,the first-ever deposition of Ni@Pd core-shell nanoparticles having different compositions on a metal-organic framework（MIL-101）was accomplished by wet impregnation in n-hexane.The Ni@Pd/MIL-101 materials were characterized by powder X-ray diffraction,Fourier transform infrared spectroscopy,transmission electron microscopy,and energy-dispersive X-ray spectroscopy and also investigated as catalysts for the hydrogenation of nitrobenzene under mild reaction conditions.At 30 °C and 0.1 MPa of H2 pressure,the Ni@Pd/MIL-101 gives a TOF as high as 375 h–1 for the hydrogenation of nitrobenzene and is applicable to a wide range of substituted nitroarenes.The exceptional performance of this catalyst is believed to result from the significant Ni-Pd interaction in the core-shell structure,together with promotion of the conversions of aromatics by uncoordinated Lewis acidic Cr sites on the MIL-101 support.
基金supported by the National Natural Science Foundation of China (Nos.52203066,51973157,61904123)the Tianjin Natural Science Foundation (No.18JCQNJC02900)+3 种基金National Innovation and Entrepreneurship Training Program for College students (No.202310058007)Tianjin Municipal College Students’ Innovation and Entrepreneurship Training Program (No.202310058088)Science & Technology Development Fund of Tianjin Education Commission for Higher Education (No.2018KJ196)State Key Laboratory of Membrane and Membrane Separation,Tiangong University
文摘Satisfactory ionic conductivity,excellent mechanical stability,and high-temperature resistance are the prerequisites for the safe application of solid polymer electrolytes(SPEs)in all-solid-state lithium metal batteries(ASSLMBs).In this study,a novel poly(m-phenylene isophthalamide)(PMIA)-core/poly(ethylene oxide)(PEO)-shell nanofiber membrane and the functional Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)ceramic nanopar-ticle are simultaneously introduced into the PEO-based SPEs to prepare composite polymer electrolytes(CPEs).The core PMIA layer of composite nanofibers can greatly improve the mechanical strength and thermal stability of the CPEs,while the shell PEO layer can provide the 3D continuous transport channels for lithium ions.In addition,the introduction of functional LLZTO nanoparticle not only reduces the crys-tallinity of PEO,but also promotes the dissociation of lithium salts and releases more Li^(+)ions through its interaction with the Lewis acid-base of anions,thereby overall improving the transport of lithium ions.Consequently,the optimized CPEs present high ionic conductivity of 1.38×10^(−4)S/cm at 30℃,signifi-cantly improved mechanical strength(8.5 MPa),remarkable thermal stability(without obvious shrinkage at 150℃),and conspicuous Li dendrites blocking ability(>1800 h).The CPEs also both have good com-patibility and cyclic stability with LiFePO_(4)(>2000 cycles)and high-voltage LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811)(>500 cycles)cathodes.In addition,even at low temperature(40℃),the assembled LiFePO4/CPEs/Li bat-tery still can cycle stably.The novel design can provide an effective way to exploit high-performance solid-state electrolytes.
基金Supported by the National Natural Science Foundation of China (Grant No 20673060)973 Project (Grant No 2009CB623502)+2 种基金the Natural Science Foundation of Tianjin (Grant No 08JCZDJC21500)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No 20070055014)the Program for New Century Excellent Talents in University (Grant No NCET-06-0215)
文摘A simple method to prepare titania nanomaterials of core-shell structure, hollow nanospheres and mesoporous nanoparticles has been developed. The core-shell nanostructures with NH4Cl as core and TiO2·xH2O-NH4Cl as shell were prepared in nonaqueous system by the deposition on the surface of the aggregated NH4Cl crystals, which could be transformed into mesoporous anatase nanoparticles or hollow nanospheres by calcination at 500°C or extraction with methanol, respectively. The hierarchical mesoporous nanostructures benefited the photocatalytic activities of the resultant titania nanomaterials, demonstrated by the UV light photodegradation of Methyl Orange.
文摘Magnetic core-shell nanoparticles have been widely studied because of their excellent and convenient magnetic and electrical properties.In this present work core-shell magneticnanoparticles (MNPs) were synthesized by simple chemical precipitation method. Firstly Mg(x)Fe(1–x)O (magnesiwuestite) nano powder samples were synthesised by low temperature chemical combustion method. Secondly the as synthesised Mg(x)Fe(1–x)O nanoparticles are used to synthesis magnetic core-shell Nano particles byusing 2-propanol, poly ethylene glycol (PEG), ammonia solution 30 wt%, tetraethyl orthosilicate (TEOS). Separation of the core-shell magnetic nanoparticles from the aqueous suspension using a centrifuge. The synthesised MNPs and core shell MNP were characterized by X-ray diffraction (XRD), Thermal gravimetric-differential thermal analyzer (TG-DTA), Transmission electron microscopy (TEM), scanning electron microscopy (SEM), (EDAX) for structural, thermal and morphological respectively. It is observed that the particle size of spherical sampleis 32.5 nm.
基金Project supported by National Natural Science Foundation of China(21425101,21331001,21371011)Ministry of Science and Technology of China(2014CB643800)
文摘The past few years witnessed extensive emergence of short-wavelength upconversion（UC） emission stimulated photoactivation studies. However, low efficiency of multi-photon process greatly limits further applications. Here, ultraviolet（UV） upconversion emissions originated from multi-photon process of Tm^3＋ were studied with Nd^3＋-sensitized NaGdF4：Yb,Tm@NaYF4：Nd,Yb core/shell nanoparticles. Crucial factors, including the contents of sensitizers Nd^3＋, Yb^3＋ and activator Tm^3＋, as well as the excitation power density were investigated based on the UV emission. Spectral results showed that high contents of Nd^3＋ in shell region up to 50%（molar fraction hereafter） and Yb^3＋ of 10% were essential to mediate the energy transfer via the core/shell interface and facilitate multi-photon UV emissions. Compared with segregated activator and sensitizer, a core/shell strategy with isolated Nd^3＋ in the shell was important for higher UV emission. Although the upconverting process was initiated with Nd^3＋→Yb^3＋, the short-wavelength emissions were intrinsically coming from four- and five-photon process. The optimized nanoparticles were found to be able to manipulate the configuration transition of azobenzene molecules, and it could be promising for near infrared（NIR） triggered optical switches applications.
