SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surfa...SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surface chemistry of these nano particles were characterized by transmission electron microscope,X-ray diffractometer and X-ray photoelectron spectroscope respectively.It was observed that Pd-doping had little effect on the grain sizes of the obtained SnO2 nano particles during the hydrothermal route.During thermal annealing,Pd-doping could restrain the growth of grain sizes below 500℃ while the grain growth was promoted when the temperature increased to above 700℃.XPS results revealed that Pd existed in three chemical states in the as-synthesized sample as Pd^0,Pd^2＋ and Pd^4＋,respectively.Pd^4＋ was the main state which was responsible for improving the gas-sensing property.The optimal Pd-doping concentration for better gas-sensing property and thermal stability was 2.0%-2.5% （mole fraction）.展开更多
It is urgent to solve the problems of the dramatic volume expansion and pulverization of SnO_2 anodes during cycling process in battery systems. To address this issue, we design a hybrid structure of N-doped carbon fi...It is urgent to solve the problems of the dramatic volume expansion and pulverization of SnO_2 anodes during cycling process in battery systems. To address this issue, we design a hybrid structure of N-doped carbon fibers@SnO_2 nanoflowers(NC@SnO_2) to overcome it in this work. The hybrid NC@SnO_2 is synthesized through the hydrothermal growth of SnO_2 nanoflowers on the surface of N-doped carbon fibers obtained by electrospinning. The NC is introduced not only to provide a support framework in guiding the growth of the SnO_2 nanoflowers and prevent the flower-like structures from agglomeration, but also serve as a conductive network to accelerate electronic transmission along one-dimensional structure effectively. When the hybrid NC@SnO_2 was served as anode, it exhibits a high discharge capacity of 750 Ah g^(-1) at 1 A g^(-1) after 100 cycles in Li-ion battery and 270 mAh g^(-1) at 100 mA g^(-1) for 100 cycles in Na-ion battery, respectively.展开更多
Crystal planes of a catalyst play crucial role in determining the electrocatalytic performance for CO2 reduction.The catalyst SnO2 can convert CO2 molecules into valuable formic acid(HCOOH).Incorporating heteroatom N ...Crystal planes of a catalyst play crucial role in determining the electrocatalytic performance for CO2 reduction.The catalyst SnO2 can convert CO2 molecules into valuable formic acid(HCOOH).Incorporating heteroatom N into SnO2 further improves its catalytic activity.To understand the mechanism and realize a highly efficient CO2-to-HCOOH conversion,we used density functional theory(DFT)to calculate the free energy of CO2 reduction reactions(CO2RR)on different crystal planes of N-doped SnO2(N-SnO2).The results indicate that N-SnO2 lowered the activation energy of intermediates leading to a better catalytic performance than pure SnO2.We also discovered that the N-Sn O2 (211)plane possesses the most suitable free energy during the reduction process,exhibiting the best catalytic ability for the CO2-to-HCOOH conversion.The intermediate of CO2RR on N-SnO2 is HCOO*or COOH* instead of OCHO*.These results may provide useful insights into the mechanism of CO2RR,and promote the development of heteroatomdoped catalyst for efficient CO2RR.展开更多
Propylene,a readily accessible and economically viable light olefin,has garnered substantial interest for its potential conversion into valuable higher olefins through oligomerization processes.The distribution of pro...Propylene,a readily accessible and economically viable light olefin,has garnered substantial interest for its potential conversion into valuable higher olefins through oligomerization processes.The distribution of products is profoundly influenced by the catalyst structure.In this study,Fe_(2)O_(3)-doped NiSO_(4)/Al_(2)O_(3) catalysts have been meticulously developed to facilitate the selective trimerization of propylene under mild conditions.Significantly,the 0.25Fe_(2)O_(3)-NiSO_(4)/Al_(2)O_(3) catalyst demonstrates an enhanced reaction rate(48.5 mmol_(C3)/(g_(cat).·h)),alongside a high yield of C9(~32.2%),significantly surpassing the performance of the NiSO_(4)/Al_(2)O_(3) catalyst(C9:~24.1%).The incorporation of Fe_(2)O_(3) modifies the migration process of sulfate ions,altering the Lewis acidity of the electron-deficient Ni and Fe sites on the catalyst and resulting a shift in product distribution from a Schulz-Flory distribution to a Poisson distribution.This shift is primarily ascribed to the heightened energy barrier for theβ-H elimination reaction in the C6 alkyl intermediates on the doped catalyst,further promoting polymerization to yield a greater quantity of Type II C9.Furthermore,the validation of the Cossee-Arlman mechanism within the reaction pathway has been confirmed.It is noteworthy that the 0.25Fe_(2)O_(3)-NiSO_(4)/Al_(2)O_(3) catalyst exhibits remarkable stability exceeding 80 h in the selective trimerization of propylene.These research findings significantly enhance our understanding of the mechanisms underlying olefin oligomerization reactions and provide invaluable insights for the development of more effective catalysts.展开更多
Tin dioxide(SnO2) and La-doped(1%,5%,10% in mass ratio) SnO2 samples were prepared via a hydrothermal method. The as-prepared powders were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM) ...Tin dioxide(SnO2) and La-doped(1%,5%,10% in mass ratio) SnO2 samples were prepared via a hydrothermal method. The as-prepared powders were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM) . Results showed that the particle size of SnO2 decreased gradually with the increase of the doped La element. When used as anode materials of Li ion battery,the La-doped samples exhibited better cycling performance than the pure SnO2,and the cycling performance of the La-doped samples got better and better with the increase of the doped La. The better electrochemical performance of the doped material could be attributed to the doping of La element,which not only enabled SnO2 powders to have a good dispersivity but also reduced their particle size.展开更多
The conversion of carbon dioxide into valuable organic compounds is a highly promising approach to address the energy issues and environmental problems(e.g., global warming). Herein, we presents a facile and efficient...The conversion of carbon dioxide into valuable organic compounds is a highly promising approach to address the energy issues and environmental problems(e.g., global warming). Herein, we presents a facile and efficient method to prepare highly dense and well-dispersed SnO2 nanocrystals on 1 D N-doped carbon nanowires as advanced catalysts for the efficient electroreduction of CO2 to formate. The ultrasmall SnO2 coated on the N-doped carbon nanowires(SnO2@N-CNW) has been synthesized via the simple hydrothermal treatment coupled with a pyrolysis process. The unique structure enables to expose the active tin oxide and also provides the facile pathways for rapid transfer of electron and electrolyte along with the highly porous carbon foam composed with interconnected carbon nanowires. Therefore, SnO2@NCNW electrocatalyst exhibits good durability and high selectivity for formate formation with a Faradaic efficiency of ca. 90%. This work demonstrates a simple method to rationally design high-dense tin oxide nanocrystals on the conductive carbon support as advanced catalysts for CO2 electroreduction.展开更多
A first-principles study has been performed to calculate the electronic and optical properties of the SbxSn1xO system.The simulations are based upon the method of generalized gradient approximations with the Perdew-Bu...A first-principles study has been performed to calculate the electronic and optical properties of the SbxSn1xO system.The simulations are based upon the method of generalized gradient approximations with the Perdew-Burke-Ernzerhof form in the framework of density functional theory.The supercell structure shows a trend from expanding to shrinking with the increasing Sb concentration.The increasing Sb concentration induces the band gap narrowing.Optical transition has shifted to the low energy range with increasing Sb concentration.Other important optical constants such as the dielectric function,reflectivity,refractive index,and electron energy loss function for Sb-doped SnO2 are discussed.The optical absorption edge of SnO2 doped with Sb also shows a redshift.展开更多
Pure SnO2 and Ce-doped(1%,4%,7%,10% in mass ratio) SnO2 powders were prepared by a simple sol-gel method.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and Bruna...Pure SnO2 and Ce-doped(1%,4%,7%,10% in mass ratio) SnO2 powders were prepared by a simple sol-gel method.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET) specific surface area analyzers.Results showed that the 7% Ce-doped sample has a particle size of 0.1-0.3 μm with a narrow particle size distribution while the pure SnO2 was consisted of large agglomerated particles with a diameter up to several micrometers.When used as the catalyst to degrade methyl orange(MO),the 7% Ce-doped sample showed best photocatalytic property.These properties can be attributed to the large surface area and small particle size of the 7% Ce-doped sample.展开更多
Nd-doped(2%,5%,10% in mass ratio) SnO2 powders were prepared via a facile hydrothermal procedure.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emme...Nd-doped(2%,5%,10% in mass ratio) SnO2 powders were prepared via a facile hydrothermal procedure.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET) specific surface area analyzers.Results showed that the Nd-doped SnO2 samples had more uniform and smaller primary particles compared with the pure sample,the particle size of the doped SnO2 decreased gradually with the increase of Nd,and the specific surface area also increased with the increase of the doped Nd.When used as gas sensing materials,the 5% and 10% Nd-doped sample showed high sensitivity and selectivity to ethanol.Furthermore,the Nd-doped sample showed fast response and recovery time to ethanol gas.This could be attributed to their small diameter,large surface area and Nd element doping.展开更多
Transparent conducting F-doped texture SnO2 films with resistivity as low as 5× 10-4 Ω ·cm,with carrier concentrations between 3.5 × 1020 and 7× 1020 cm-3 and Hall mobilities from 15.7 to 20.1 cm2...Transparent conducting F-doped texture SnO2 films with resistivity as low as 5× 10-4 Ω ·cm,with carrier concentrations between 3.5 × 1020 and 7× 1020 cm-3 and Hall mobilities from 15.7 to 20.1 cm2/(V/s) have been prepared by atmosphere pressure chemical vapour deposition (APCVD). These polycrystalline films possess a variable preferred orientation, the polycrystallite sizes and orientations vary with substrate temperature. The substrate temperature and fluorine flow rate dependence of conductivity, Hall mobility and carrier conentration fOr the resultingfilms have been obtained. The temperature dependence of the mobiity and carrier concentrationhave been measured over a temperature range 16～400 K. A systematically theoretical analysis on scattering mechanisms for the highly conductive SnO2 films has been given. Both theoretical analysis and experimental results indicate that for these degenerate, polycrystalline SnO2 ：F films in the low temperature range (below 100 K), ionized impurity scattering is main scattering mechanism. However, when the temperature is higher than 100 K, the lattice vibration scattering becomes dominant. The grain boundary scattering makes a small contribution to limit the mobility of the films.展开更多
The study of nanocrystalline SnO2 (n-SnO2) and SiO2-doped SnO2 (n-Si-SnO2) samples pre-pared by the sol-gel process showed that SiO2 doping can effectively restrained the growth of nanocrystalline SnO2 grains, thus im...The study of nanocrystalline SnO2 (n-SnO2) and SiO2-doped SnO2 (n-Si-SnO2) samples pre-pared by the sol-gel process showed that SiO2 doping can effectively restrained the growth of nanocrystalline SnO2 grains, thus improving thermal stability of the materials.展开更多
In the present work the structural information of PbO-doped SnO2 thick film sensor has been investigated with X-ray diffractometer （XRD） and scanning electron microscope （SEM）. Initially, SnO2 powder was derived u...In the present work the structural information of PbO-doped SnO2 thick film sensor has been investigated with X-ray diffractometer （XRD） and scanning electron microscope （SEM）. Initially, SnO2 powder was derived using sol-gel process and was subsequently doped with PbO and ground up to nanosized particles. A suitable gas sensor structure was fabricated on 1′′×1′′ alumina substrate using thick film technology. The necessary paste for screen printing was also developed. SEM results showed sol-gel derived powder gets more agglomerated in the thick film form. The sensitivity of the sensor has been investigated at different temperatures （150 ？C？350 ？C） upon exposure to methanol, propanol and acetone, yielding a maximum at 250 ？C for acetone with 1 wt% PbO-doping while at 350 ？C for propanol with 3 wt% PbO-doping of the sensor. The reduction of particle size to nanometers （validated through XRD） leads to a dramatic improvement in sensitivity of sensors for the chosen organic vapors. The results also correlate well with the microstructural properties of the material and the dopant.展开更多
To understand the effect of the doping amount of Cu^2+ on the structure and reactivity of SnO2 in NOx-SCR with NH3, a series of Sn-Cu-O binary oxide catalysts with different Sn/Cu ratios have been prepared and thoroug...To understand the effect of the doping amount of Cu^2+ on the structure and reactivity of SnO2 in NOx-SCR with NH3, a series of Sn-Cu-O binary oxide catalysts with different Sn/Cu ratios have been prepared and thoroughly characterized. Using the XRD extrapolation method, the SnO2 lattice capacity for Cu^2+ cations is determined at 0.10 g Cu O per g of SnO2, equaling a Sn/Cu molar ratio of 84/16. Therefore, in a tetragonal rutile SnO2 lattice, only a maximum of 16% of the Sn4+ cations can be replaced by Cu^2+ to form a stable solid solution structure. If the Cu content is higher, Cu O will form on the catalyst surface, which has a negative effect on the reaction performance. For samples in a pure solid solution phase, the number of surface defects increase with increasing Cu content until it reaches the lattice capacity, as confirmed by Raman spectroscopy. As a result, the amounts of both active oxygen species and acidic sites on the surface, which critically determine the reaction performance, also increase and reach the maximum level for the catalyst with a Cu content close to the lattice capacity. A distinct lattice capacity threshold effect on the structure and reactivity of Sn-Cu binary oxide catalysts has been observed. A Sn-Cu catalyst with the best reaction performance can be obtained by doping the SnO2 matrix with the lattice capacity amount of Cu^2+.展开更多
Polycrystalline samples of（Zn, Co） co-doped SnO2 nanoparticles were prepared using a co-precipitation method. The influence of（Zn, Co） co-doping on electrical, dielectric, and magnetic properties was studied. All ...Polycrystalline samples of（Zn, Co） co-doped SnO2 nanoparticles were prepared using a co-precipitation method. The influence of（Zn, Co） co-doping on electrical, dielectric, and magnetic properties was studied. All of the（Zn, Co） co-doped SnO2 powder samples have the same tetragonal structure of SnO2. A decrease in the dielectric constant was observed with the increase of Co doping concentration. It was found that the dielectric constant and dielectric loss values decrease, while AC electrical conductivity increases with doping concentration and frequency. Magnetization measurements revealed that the Co doping SnO2 samples exhibits room temperature ferromagnetism. Our results illustrate that（Zn, Co） co-doped SnO2 nanoparticles have an excellent dielectric, magnetic properties, and high electrical conductivity than those reported previously, indicating that these（Zn, Co） co-doped SnO2 materials can be used in the field of the ultrahigh dielectric material, high frequency device, and spintronics.展开更多
All-solid-state electrolytes are exceedingly attractive because of the outstanding inherent safety and energy density compared to liquid electrolytes.Whereas,it is still formidable to simultaneously design solid elect...All-solid-state electrolytes are exceedingly attractive because of the outstanding inherent safety and energy density compared to liquid electrolytes.Whereas,it is still formidable to simultaneously design solid electrolytes with favorable electrode/electrolyte interface compatibility and high ionic conductivity in a simple and scalable manner.Hence,the oxygen-vacancy-rich Gd-doped SnO_(2) nanotubes(GDS NTs)are innovatively prepared and applied to the electrolyte of all-solid-state lithium metal batteries for the first time.The addition of GDS NTs can validly construct long-range co ntinuous ion transport networks in the poly(ethylene oxide)(PEO)-based system and greatly improve the mechanical properties of the electrolyte.Compared to the PEO-based electrolyte,the composite electrolyte displays a higher lithium ion conductivity of 2.41×10^(-4) S cm^(-1) at 30℃,a higher lithium ion transference number up to 0.62 and a wider electrochemical window of 5 V at 50℃.In addition,the composite electrolyte manifests outstanding compatibility with high-voltage LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811)cathode,LiFePO4 cathode and lithium metal anode.The assembled Li/Li symmetric battery exhibits stable Li plating/stripping cycling performance,which can cycle steadily for 1500 h at a capacity of 0.3 mA h cm^(-2).And Li/LiFePO4 battery still maintains a high capacity of 131.54 mA h g^(-1) at 0.5C after 800 cycles,which has a superior capacity retention rate of 93.2%.The obtained novel composite electrolyte has promising application prospects in the field of all-solid-state lithium metal cells.展开更多
Porous Cu-doped SnO<sub>2</sub> thin films were synthesized by the sol-gel dip-coating method for enhancing methanol sensing performance. The effect of Cu doping concentration on the SnO<sub>2</su...Porous Cu-doped SnO<sub>2</sub> thin films were synthesized by the sol-gel dip-coating method for enhancing methanol sensing performance. The effect of Cu doping concentration on the SnO<sub>2</sub> sensibility was investigated. XRD data confirm that the fabricated SnO<sub>2</sub> films are polycrystalline with tetragonal rutile crystal structure. AFM and SEM micrographs confirmed the roughness and the porosity of SnO<sub>2</sub> surface, respectively. UV-Vis spectrum shows that SnO<sub>2</sub> thin films exhibit high transmittance in the visible region ~95%. The band gap (3.80 - 3.92 eV) and the optical thickness (893 - 131 nm) of prepared films were calculated from transmittance data. The sensing results demonstrate that SnO<sub>2</sub> films have a high sensitivity and a fast response to methanol. In particular, 3% Cu-SnO<sub>2</sub> films have a higher sensitivity (98%), faster response (10-<sup>2</sup> s) and shorter recovery time (18 s) than other films.展开更多
In this work,Eu^(3+)-doped CsPbCl_(2)Br_(1) in borosilicate glass was successfully synthesized by the melt quenching annealing technique and crystallization method.This work reports a novel Eu^(3+)-doped CsPbCl_(2)Br_...In this work,Eu^(3+)-doped CsPbCl_(2)Br_(1) in borosilicate glass was successfully synthesized by the melt quenching annealing technique and crystallization method.This work reports a novel Eu^(3+)-doped CsPbCl_(2)Br_(1) perovskite quantum dots(QDs)glass with high sensitivity for optical temperature sensing.The relation of fluorescence intensity ratio(FIR)with the temperature was studied in the temperature range of 80-440 K.Notably,the maximum absolute temperature sensitivity(Sa)and relative temperature sensitivity(Sr)of Eu^(3+)-doped CsPbCl_(2)Br_(1) perovskite QDs glass can reach as high as 0.0315 K-1 and3.097%/K,respectively.Meanwhile,Eu^(3+)-doped CsPbCl_(2)Br_(1) QDs glass demonstrates good water resistance,excellent thermal and cold cycling stability performance,The Eu^(3+)-doped QDs glass materials can bring inspiration to the future exploration of rare earth ion-doped QDs glass material on the application of optical temperature sensing in the future.展开更多
Cu^2＋-doped nanostructured TiO2-coated SiO2 （TiO2/SiO2） particles were prepared by the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized by the sol-gel ...Cu^2＋-doped nanostructured TiO2-coated SiO2 （TiO2/SiO2） particles were prepared by the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized by the sol-gel method using TiOSO4 as a precursor. The experimental results showed that TiO2 nanopowders on the surface of SiO2 particles were well distributed and compact. The amount of TiO2 increased with the increase in coating layers. The shell structure appeared to be composed of anatase titania nanocrystals at 550℃. The 2-layer coated TiO2 particles on the surface showed a higher degradation rate compared with all the different-layer samples. The photocatalytic activity of Cu^2＋-doped TiO2/SiO2 was higher than that ofundoped TiO2/SiO2. The optimum dopant content was about 0.10wt%.展开更多
Physical vapor deposition(PVD)can be used to produce high-quality Gd_(2)O_(3)-doped CeO2(GDC)films.Among various PVD methods,reactive sputtering provides unique benefits,such as high deposition rates and easy upscalin...Physical vapor deposition(PVD)can be used to produce high-quality Gd_(2)O_(3)-doped CeO2(GDC)films.Among various PVD methods,reactive sputtering provides unique benefits,such as high deposition rates and easy upscaling for industrial applications.GDC thin films were successfully fabricated through reactive sputtering using a Gd_(0.2)Ce_(0.8)(at%)metallic target,and their application in solid oxide fuel cells,such as buffer layers between yttria-stabilized zirconia(YSZ)/La0.6Sr0.4Co0.2Fe0.8O_(3−δ)and as sublayers in the steel/coating system,was evaluated.First,the direct current(DC)reactive-sputtering behavior of the GdCe metallic target was determined.Then,the GDC films were deposited on NiO-YSZ/YSZ half-cells to investigate the influence of oxygen flow rate on the quality of annealed GDC films.The results demonstrated that reactive sputtering can be used to prepare thin and dense GDC buffer layers without high-temperature sintering.Furthermore,the cells with a sputtered GDC buffer layer showed better electrochemical performance than those with a screen-printed GDC buffer layer.In addition,the insertion of a GDC sublayer between the SUS441 interconnects and the Mn-Co spinel coatings contributed to the reduction of the oxidation rate for SUS441 at operating temperatures,according to the area-specific resistance tests.展开更多
基金Projects(60806032,20975107) supported by the National Natural Science Foundation of ChinaProject(2009R10064) supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars of Education Ministry,China+2 种基金 Project(2009R10064) supported by "Qianjiang Talent Program"Projects(2009A610058,2009A610030) supported by the Ningbo Natural Science Foundation,ChinaProject supported by K.C.WONG Magna Fund in Ningbo University,China
文摘SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surface chemistry of these nano particles were characterized by transmission electron microscope,X-ray diffractometer and X-ray photoelectron spectroscope respectively.It was observed that Pd-doping had little effect on the grain sizes of the obtained SnO2 nano particles during the hydrothermal route.During thermal annealing,Pd-doping could restrain the growth of grain sizes below 500℃ while the grain growth was promoted when the temperature increased to above 700℃.XPS results revealed that Pd existed in three chemical states in the as-synthesized sample as Pd^0,Pd^2＋ and Pd^4＋,respectively.Pd^4＋ was the main state which was responsible for improving the gas-sensing property.The optimal Pd-doping concentration for better gas-sensing property and thermal stability was 2.0%-2.5% （mole fraction）.
基金supported by the National Natural Science Foundation of China (Grant No. 51302079)the National Natural Science Foundation of Hunan Province (Grant No. 2017JJ1008)
文摘It is urgent to solve the problems of the dramatic volume expansion and pulverization of SnO_2 anodes during cycling process in battery systems. To address this issue, we design a hybrid structure of N-doped carbon fibers@SnO_2 nanoflowers(NC@SnO_2) to overcome it in this work. The hybrid NC@SnO_2 is synthesized through the hydrothermal growth of SnO_2 nanoflowers on the surface of N-doped carbon fibers obtained by electrospinning. The NC is introduced not only to provide a support framework in guiding the growth of the SnO_2 nanoflowers and prevent the flower-like structures from agglomeration, but also serve as a conductive network to accelerate electronic transmission along one-dimensional structure effectively. When the hybrid NC@SnO_2 was served as anode, it exhibits a high discharge capacity of 750 Ah g^(-1) at 1 A g^(-1) after 100 cycles in Li-ion battery and 270 mAh g^(-1) at 100 mA g^(-1) for 100 cycles in Na-ion battery, respectively.
基金supported by the National Natural Science Foundation of China (51302079)the Natural Science Foundation of Hunan Province (Grant No. 2017JJ1008)
文摘Crystal planes of a catalyst play crucial role in determining the electrocatalytic performance for CO2 reduction.The catalyst SnO2 can convert CO2 molecules into valuable formic acid(HCOOH).Incorporating heteroatom N into SnO2 further improves its catalytic activity.To understand the mechanism and realize a highly efficient CO2-to-HCOOH conversion,we used density functional theory(DFT)to calculate the free energy of CO2 reduction reactions(CO2RR)on different crystal planes of N-doped SnO2(N-SnO2).The results indicate that N-SnO2 lowered the activation energy of intermediates leading to a better catalytic performance than pure SnO2.We also discovered that the N-Sn O2 (211)plane possesses the most suitable free energy during the reduction process,exhibiting the best catalytic ability for the CO2-to-HCOOH conversion.The intermediate of CO2RR on N-SnO2 is HCOO*or COOH* instead of OCHO*.These results may provide useful insights into the mechanism of CO2RR,and promote the development of heteroatomdoped catalyst for efficient CO2RR.
文摘Propylene,a readily accessible and economically viable light olefin,has garnered substantial interest for its potential conversion into valuable higher olefins through oligomerization processes.The distribution of products is profoundly influenced by the catalyst structure.In this study,Fe_(2)O_(3)-doped NiSO_(4)/Al_(2)O_(3) catalysts have been meticulously developed to facilitate the selective trimerization of propylene under mild conditions.Significantly,the 0.25Fe_(2)O_(3)-NiSO_(4)/Al_(2)O_(3) catalyst demonstrates an enhanced reaction rate(48.5 mmol_(C3)/(g_(cat).·h)),alongside a high yield of C9(~32.2%),significantly surpassing the performance of the NiSO_(4)/Al_(2)O_(3) catalyst(C9:~24.1%).The incorporation of Fe_(2)O_(3) modifies the migration process of sulfate ions,altering the Lewis acidity of the electron-deficient Ni and Fe sites on the catalyst and resulting a shift in product distribution from a Schulz-Flory distribution to a Poisson distribution.This shift is primarily ascribed to the heightened energy barrier for theβ-H elimination reaction in the C6 alkyl intermediates on the doped catalyst,further promoting polymerization to yield a greater quantity of Type II C9.Furthermore,the validation of the Cossee-Arlman mechanism within the reaction pathway has been confirmed.It is noteworthy that the 0.25Fe_(2)O_(3)-NiSO_(4)/Al_(2)O_(3) catalyst exhibits remarkable stability exceeding 80 h in the selective trimerization of propylene.These research findings significantly enhance our understanding of the mechanisms underlying olefin oligomerization reactions and provide invaluable insights for the development of more effective catalysts.
基金Project supported by the National Natural Science Foundation of China (20871107)Henan Outstanding Youth Science Fund (0612002700)the Natural Science Foundation of the Education Department of Henan Province (2009A150031)
文摘Tin dioxide(SnO2) and La-doped(1%,5%,10% in mass ratio) SnO2 samples were prepared via a hydrothermal method. The as-prepared powders were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM) . Results showed that the particle size of SnO2 decreased gradually with the increase of the doped La element. When used as anode materials of Li ion battery,the La-doped samples exhibited better cycling performance than the pure SnO2,and the cycling performance of the La-doped samples got better and better with the increase of the doped La. The better electrochemical performance of the doped material could be attributed to the doping of La element,which not only enabled SnO2 powders to have a good dispersivity but also reduced their particle size.
基金financially supported by Guangdong Province Science and Technology Plan Project for Public Welfare Fund and Ability Construction Project(JCYJ20180301171324915)the National Natural Science Foundation of China(No.21503116)+1 种基金Taishan Scholars Program of Shandong Province(No.tsqn20161004)the Youth 1000 Talent Program of China。
文摘The conversion of carbon dioxide into valuable organic compounds is a highly promising approach to address the energy issues and environmental problems(e.g., global warming). Herein, we presents a facile and efficient method to prepare highly dense and well-dispersed SnO2 nanocrystals on 1 D N-doped carbon nanowires as advanced catalysts for the efficient electroreduction of CO2 to formate. The ultrasmall SnO2 coated on the N-doped carbon nanowires(SnO2@N-CNW) has been synthesized via the simple hydrothermal treatment coupled with a pyrolysis process. The unique structure enables to expose the active tin oxide and also provides the facile pathways for rapid transfer of electron and electrolyte along with the highly porous carbon foam composed with interconnected carbon nanowires. Therefore, SnO2@NCNW electrocatalyst exhibits good durability and high selectivity for formate formation with a Faradaic efficiency of ca. 90%. This work demonstrates a simple method to rationally design high-dense tin oxide nanocrystals on the conductive carbon support as advanced catalysts for CO2 electroreduction.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No. BUPT2009RC0412the National Natural Science Foundation of China under Grant Nos. 60908028 and 60971068
文摘A first-principles study has been performed to calculate the electronic and optical properties of the SbxSn1xO system.The simulations are based upon the method of generalized gradient approximations with the Perdew-Burke-Ernzerhof form in the framework of density functional theory.The supercell structure shows a trend from expanding to shrinking with the increasing Sb concentration.The increasing Sb concentration induces the band gap narrowing.Optical transition has shifted to the low energy range with increasing Sb concentration.Other important optical constants such as the dielectric function,reflectivity,refractive index,and electron energy loss function for Sb-doped SnO2 are discussed.The optical absorption edge of SnO2 doped with Sb also shows a redshift.
基金Project supported by the National Natural Science Foundation of China (20871107)He'nan Outstanding Youth Science Fund (0612002700)the Natural Science Foundation of the Education Department of Henan Province (2009A150031)
文摘Pure SnO2 and Ce-doped(1%,4%,7%,10% in mass ratio) SnO2 powders were prepared by a simple sol-gel method.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET) specific surface area analyzers.Results showed that the 7% Ce-doped sample has a particle size of 0.1-0.3 μm with a narrow particle size distribution while the pure SnO2 was consisted of large agglomerated particles with a diameter up to several micrometers.When used as the catalyst to degrade methyl orange(MO),the 7% Ce-doped sample showed best photocatalytic property.These properties can be attributed to the large surface area and small particle size of the 7% Ce-doped sample.
基金Project supported by the National Natural Science Foundation of China (20871107)He'nan Outstanding Youth Science Fund (0612002700)the Natural Science Foundation of the Education Department of Henan Province (2009A150031)
文摘Nd-doped(2%,5%,10% in mass ratio) SnO2 powders were prepared via a facile hydrothermal procedure.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET) specific surface area analyzers.Results showed that the Nd-doped SnO2 samples had more uniform and smaller primary particles compared with the pure sample,the particle size of the doped SnO2 decreased gradually with the increase of Nd,and the specific surface area also increased with the increase of the doped Nd.When used as gas sensing materials,the 5% and 10% Nd-doped sample showed high sensitivity and selectivity to ethanol.Furthermore,the Nd-doped sample showed fast response and recovery time to ethanol gas.This could be attributed to their small diameter,large surface area and Nd element doping.
文摘Transparent conducting F-doped texture SnO2 films with resistivity as low as 5× 10-4 Ω ·cm,with carrier concentrations between 3.5 × 1020 and 7× 1020 cm-3 and Hall mobilities from 15.7 to 20.1 cm2/(V/s) have been prepared by atmosphere pressure chemical vapour deposition (APCVD). These polycrystalline films possess a variable preferred orientation, the polycrystallite sizes and orientations vary with substrate temperature. The substrate temperature and fluorine flow rate dependence of conductivity, Hall mobility and carrier conentration fOr the resultingfilms have been obtained. The temperature dependence of the mobiity and carrier concentrationhave been measured over a temperature range 16～400 K. A systematically theoretical analysis on scattering mechanisms for the highly conductive SnO2 films has been given. Both theoretical analysis and experimental results indicate that for these degenerate, polycrystalline SnO2 ：F films in the low temperature range (below 100 K), ionized impurity scattering is main scattering mechanism. However, when the temperature is higher than 100 K, the lattice vibration scattering becomes dominant. The grain boundary scattering makes a small contribution to limit the mobility of the films.
文摘The study of nanocrystalline SnO2 (n-SnO2) and SiO2-doped SnO2 (n-Si-SnO2) samples pre-pared by the sol-gel process showed that SiO2 doping can effectively restrained the growth of nanocrystalline SnO2 grains, thus improving thermal stability of the materials.
文摘In the present work the structural information of PbO-doped SnO2 thick film sensor has been investigated with X-ray diffractometer （XRD） and scanning electron microscope （SEM）. Initially, SnO2 powder was derived using sol-gel process and was subsequently doped with PbO and ground up to nanosized particles. A suitable gas sensor structure was fabricated on 1′′×1′′ alumina substrate using thick film technology. The necessary paste for screen printing was also developed. SEM results showed sol-gel derived powder gets more agglomerated in the thick film form. The sensitivity of the sensor has been investigated at different temperatures （150 ？C？350 ？C） upon exposure to methanol, propanol and acetone, yielding a maximum at 250 ？C for acetone with 1 wt% PbO-doping while at 350 ？C for propanol with 3 wt% PbO-doping of the sensor. The reduction of particle size to nanometers （validated through XRD） leads to a dramatic improvement in sensitivity of sensors for the chosen organic vapors. The results also correlate well with the microstructural properties of the material and the dopant.
文摘To understand the effect of the doping amount of Cu^2+ on the structure and reactivity of SnO2 in NOx-SCR with NH3, a series of Sn-Cu-O binary oxide catalysts with different Sn/Cu ratios have been prepared and thoroughly characterized. Using the XRD extrapolation method, the SnO2 lattice capacity for Cu^2+ cations is determined at 0.10 g Cu O per g of SnO2, equaling a Sn/Cu molar ratio of 84/16. Therefore, in a tetragonal rutile SnO2 lattice, only a maximum of 16% of the Sn4+ cations can be replaced by Cu^2+ to form a stable solid solution structure. If the Cu content is higher, Cu O will form on the catalyst surface, which has a negative effect on the reaction performance. For samples in a pure solid solution phase, the number of surface defects increase with increasing Cu content until it reaches the lattice capacity, as confirmed by Raman spectroscopy. As a result, the amounts of both active oxygen species and acidic sites on the surface, which critically determine the reaction performance, also increase and reach the maximum level for the catalyst with a Cu content close to the lattice capacity. A distinct lattice capacity threshold effect on the structure and reactivity of Sn-Cu binary oxide catalysts has been observed. A Sn-Cu catalyst with the best reaction performance can be obtained by doping the SnO2 matrix with the lattice capacity amount of Cu^2+.
基金Project supported by the National Basic Research Program of China(Grant Nos.2015CB9210042012CB821404+1 种基金and 2011CBA00103)the National Natural Science Foundation of China(Grant Nos.11374261 and 11204059)
文摘Polycrystalline samples of（Zn, Co） co-doped SnO2 nanoparticles were prepared using a co-precipitation method. The influence of（Zn, Co） co-doping on electrical, dielectric, and magnetic properties was studied. All of the（Zn, Co） co-doped SnO2 powder samples have the same tetragonal structure of SnO2. A decrease in the dielectric constant was observed with the increase of Co doping concentration. It was found that the dielectric constant and dielectric loss values decrease, while AC electrical conductivity increases with doping concentration and frequency. Magnetization measurements revealed that the Co doping SnO2 samples exhibits room temperature ferromagnetism. Our results illustrate that（Zn, Co） co-doped SnO2 nanoparticles have an excellent dielectric, magnetic properties, and high electrical conductivity than those reported previously, indicating that these（Zn, Co） co-doped SnO2 materials can be used in the field of the ultrahigh dielectric material, high frequency device, and spintronics.
基金supported by the National Natural Science Foundation of China(52203066,51973157,61904123,51873152)the Tianjin Natural Science Foundation(18JCQNJC02900)+3 种基金the Science and Technology Plans of Tianjin(19PTSYJC00010)the Tianjin Research Innovation Project for Postgraduate Students(2021YJSB234)the Science&Technology Development Fund of Tianjin Education Commission for Higher Education(2018KJ196)State Key Laboratory of Membrane and Membrane Separation,Tiangong University。
文摘All-solid-state electrolytes are exceedingly attractive because of the outstanding inherent safety and energy density compared to liquid electrolytes.Whereas,it is still formidable to simultaneously design solid electrolytes with favorable electrode/electrolyte interface compatibility and high ionic conductivity in a simple and scalable manner.Hence,the oxygen-vacancy-rich Gd-doped SnO_(2) nanotubes(GDS NTs)are innovatively prepared and applied to the electrolyte of all-solid-state lithium metal batteries for the first time.The addition of GDS NTs can validly construct long-range co ntinuous ion transport networks in the poly(ethylene oxide)(PEO)-based system and greatly improve the mechanical properties of the electrolyte.Compared to the PEO-based electrolyte,the composite electrolyte displays a higher lithium ion conductivity of 2.41×10^(-4) S cm^(-1) at 30℃,a higher lithium ion transference number up to 0.62 and a wider electrochemical window of 5 V at 50℃.In addition,the composite electrolyte manifests outstanding compatibility with high-voltage LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811)cathode,LiFePO4 cathode and lithium metal anode.The assembled Li/Li symmetric battery exhibits stable Li plating/stripping cycling performance,which can cycle steadily for 1500 h at a capacity of 0.3 mA h cm^(-2).And Li/LiFePO4 battery still maintains a high capacity of 131.54 mA h g^(-1) at 0.5C after 800 cycles,which has a superior capacity retention rate of 93.2%.The obtained novel composite electrolyte has promising application prospects in the field of all-solid-state lithium metal cells.
文摘Porous Cu-doped SnO<sub>2</sub> thin films were synthesized by the sol-gel dip-coating method for enhancing methanol sensing performance. The effect of Cu doping concentration on the SnO<sub>2</sub> sensibility was investigated. XRD data confirm that the fabricated SnO<sub>2</sub> films are polycrystalline with tetragonal rutile crystal structure. AFM and SEM micrographs confirmed the roughness and the porosity of SnO<sub>2</sub> surface, respectively. UV-Vis spectrum shows that SnO<sub>2</sub> thin films exhibit high transmittance in the visible region ~95%. The band gap (3.80 - 3.92 eV) and the optical thickness (893 - 131 nm) of prepared films were calculated from transmittance data. The sensing results demonstrate that SnO<sub>2</sub> films have a high sensitivity and a fast response to methanol. In particular, 3% Cu-SnO<sub>2</sub> films have a higher sensitivity (98%), faster response (10-<sup>2</sup> s) and shorter recovery time (18 s) than other films.
基金Project supported by the National Natural Science Foundation of China(51872207,51672192)。
文摘In this work,Eu^(3+)-doped CsPbCl_(2)Br_(1) in borosilicate glass was successfully synthesized by the melt quenching annealing technique and crystallization method.This work reports a novel Eu^(3+)-doped CsPbCl_(2)Br_(1) perovskite quantum dots(QDs)glass with high sensitivity for optical temperature sensing.The relation of fluorescence intensity ratio(FIR)with the temperature was studied in the temperature range of 80-440 K.Notably,the maximum absolute temperature sensitivity(Sa)and relative temperature sensitivity(Sr)of Eu^(3+)-doped CsPbCl_(2)Br_(1) perovskite QDs glass can reach as high as 0.0315 K-1 and3.097%/K,respectively.Meanwhile,Eu^(3+)-doped CsPbCl_(2)Br_(1) QDs glass demonstrates good water resistance,excellent thermal and cold cycling stability performance,The Eu^(3+)-doped QDs glass materials can bring inspiration to the future exploration of rare earth ion-doped QDs glass material on the application of optical temperature sensing in the future.
基金the Department of Education of Hebei Province, China (No.2005362)
文摘Cu^2＋-doped nanostructured TiO2-coated SiO2 （TiO2/SiO2） particles were prepared by the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized by the sol-gel method using TiOSO4 as a precursor. The experimental results showed that TiO2 nanopowders on the surface of SiO2 particles were well distributed and compact. The amount of TiO2 increased with the increase in coating layers. The shell structure appeared to be composed of anatase titania nanocrystals at 550℃. The 2-layer coated TiO2 particles on the surface showed a higher degradation rate compared with all the different-layer samples. The photocatalytic activity of Cu^2＋-doped TiO2/SiO2 was higher than that ofundoped TiO2/SiO2. The optimum dopant content was about 0.10wt%.
基金financially supported by the National Key R&D Program of China (No. 2018YFB1502203-1)the Guangdong Basic and Applied Basic Research Foundation (No. 2021B1515120087)the Stable Supporting Fund of Shenzhen, China (No. GXWD20201230155427003-202007 28114835006)
文摘Physical vapor deposition(PVD)can be used to produce high-quality Gd_(2)O_(3)-doped CeO2(GDC)films.Among various PVD methods,reactive sputtering provides unique benefits,such as high deposition rates and easy upscaling for industrial applications.GDC thin films were successfully fabricated through reactive sputtering using a Gd_(0.2)Ce_(0.8)(at%)metallic target,and their application in solid oxide fuel cells,such as buffer layers between yttria-stabilized zirconia(YSZ)/La0.6Sr0.4Co0.2Fe0.8O_(3−δ)and as sublayers in the steel/coating system,was evaluated.First,the direct current(DC)reactive-sputtering behavior of the GdCe metallic target was determined.Then,the GDC films were deposited on NiO-YSZ/YSZ half-cells to investigate the influence of oxygen flow rate on the quality of annealed GDC films.The results demonstrated that reactive sputtering can be used to prepare thin and dense GDC buffer layers without high-temperature sintering.Furthermore,the cells with a sputtered GDC buffer layer showed better electrochemical performance than those with a screen-printed GDC buffer layer.In addition,the insertion of a GDC sublayer between the SUS441 interconnects and the Mn-Co spinel coatings contributed to the reduction of the oxidation rate for SUS441 at operating temperatures,according to the area-specific resistance tests.
