The effect of annealing on microstructure, adhesive and frictional properties of GeSb2Te4 films were experimentally studied. The GeSb2Te4 films were prepared by radio frequency （RF） magnetron sputtering, and anneale...The effect of annealing on microstructure, adhesive and frictional properties of GeSb2Te4 films were experimentally studied. The GeSb2Te4 films were prepared by radio frequency （RF） magnetron sputtering, and annealed at 200℃ and 340℃ under vacuum circumstance, respectively. The adhesion and friction experiments were mainly conducted with a lateral force microscope （LFM） for the GeSb2Te4 thin films before and after annealing. Their morphology and phase structure were analyzed by using atomic force microscopy （AFM） and X-ray Diffraction （XRD） techniques, and the nanoindention was employed to evaluate their hardness values. Moreover, an electric force microscope （EFM） was used to measure the surface potential. It is found that the deposited GeSb2Te4 thin film undergoes an amorphous-to-fcc and fcc-to-hex structure transition; the adhesion has a weaker dependence on the surface roughness, but a certain correlation with the surface potential of GeSb2Te4 thin films. And the friction behavior of GeSb2Te4 thin films follows their adhesion behavior under a lower applied load. However, such a relation is replaced by the mechanical behavior when the load is relatively higher. Moreover, the GeSb2Te4 thin film annealed at 340℃ presents a lubricative property.展开更多
To further extend knowledge about the detailed knowledge on the crossflow characteristics in a multi-jets system under a confined space,particle image velocimetry (PIV) was employed to investigate the flow structures ...To further extend knowledge about the detailed knowledge on the crossflow characteristics in a multi-jets system under a confined space,particle image velocimetry (PIV) was employed to investigate the flow structures together with the distributions of the mean velocity components for Reynolds numbers (Re) ranging from 6 213 to 13 418,nozzle-to-plate spacing (H/D) varying from 0. 20 to1. 25,respectively. Results show that the crossflow configuration is significantly different from those of large nozzle-to-plate spacing. In addition,a turning point H/D=0.50 is revealed in the profile of the normalized maximum radial velocity which is associated with the heat transfer distribution on the impingement plate.展开更多
Achieving high-quality perovskite crystal films is a critical prerequisite in boosting solar cell efficiency and improving the device stability,but the delicate control of nucleation and growth of the perovskite film ...Achieving high-quality perovskite crystal films is a critical prerequisite in boosting solar cell efficiency and improving the device stability,but the delicate control of nucleation and growth of the perovskite film remains limited success.Herein,a facile but effective strategy has been developed to finely tailor the crystallization of thermally stable cesium/formamidinium(Cs/FA)based perovskite via partially replacing PbI2 with PbCl2 in the precursor solution.The incorporation of chlorine into the perovskite crystal lattice derived from PbCl2 changes the crystallization process and improves the crystal quality,which further results in the formation of larger crystal grains compared to the control sample.The larger crystal grains with high crystallinity lead to reduced grain boundaries,suppressed non-radiative recombination,and enhanced photoluminescence lifetime.Under the optimized conditions,the methylammonium free perovskite solar cells(PSCs)delivers a champion power conversion efficiency(PCE)of 21.30%with an open-circuit voltage as high as 1.18 V,which is one of the highest efficiencies for Cs/FA based PSCs up to now.Importantly,the unencapsulated PSC devices retain more than 95%and 81%of their original PCEs even after long-term(over one year)storage under ambient conditions or 2000 h’s thermal aging at 850C in a nitrogen atmosphere,respectively.展开更多
Interface engineering is an effective way to improve efficiency and long-term stability of perovskite solar cells(PSCs).Herein,an ionic compound tetrabutylammonium hexafluorophosphate(TP6)is adopted to passivate surfa...Interface engineering is an effective way to improve efficiency and long-term stability of perovskite solar cells(PSCs).Herein,an ionic compound tetrabutylammonium hexafluorophosphate(TP6)is adopted to passivate surface defects of the perovskite film.It is found that TP6 effectively reduced the surface defects,especially at the grain boundaries where the defects are abundant.Meanwhile,the exposed long alkyl chains and fluorine atoms in the TP6 enhanced the moisture stability of the perovskite film due to its strong hydrophobicity.In addition,the driving force of charge carrier separation and transport is increased by enlarged built-in potential.Consequently,the power conversion efficiency(PCE)of PSCs is significantly improved from 20.59% to 22.41%by increased open-circuit voltage(V_(oc))and fill factor(FF).The unencapsulated device with TP6 treatment exhibits better stability than the control device,and the PCE retains-80%of its initial PCE after 30 days under 15%-25%relative humidity in storage,while the PCE of the control device declines by more than 50%.展开更多
GeSb2Te4 films were deposited on Si substrates by RF magnetron sputtering,and the effects of sputtering power on the surface topography and anti-compression properties were studied with atomic force microscope(AFM)and...GeSb2Te4 films were deposited on Si substrates by RF magnetron sputtering,and the effects of sputtering power on the surface topography and anti-compression properties were studied with atomic force microscope(AFM)and nanoindenter.Meanwhile,the mechanical properties of GeSb2Te4 films with oxygen impurity were also investigated.The results indicate that proper sputtering power is important for obtaining GeSb2Te4 films with high compact structure and low surface roughness,which present good load-support capacity.Although the effect of oxygen impurity on the anti-compression properties of GeSb2Te4 films is not very significant as a whole,certain oxygen dosage can relax the internal stress,thereby the hardness of the films drops slightly.展开更多
BaMgAl10 O17 ：Mn^2＋ green phosphor was prepared by high temperature solid state reaction and the optimal chemical formula is Ba0.85MgMn0.15Al11.993 B0.007 O19. The influences of milling and ultrasonic-dispersal on t...BaMgAl10 O17 ：Mn^2＋ green phosphor was prepared by high temperature solid state reaction and the optimal chemical formula is Ba0.85MgMn0.15Al11.993 B0.007 O19. The influences of milling and ultrasonic-dispersal on the luminescent properties, granularity and appearance of the phosphor were investigated, and the green phosphor with fine grain and uniform dispersion to be adapted to plasma display panels was obtained. A Hitachi F-4500 fluorescence spectrophotometer was used to measure the luminescent performance of the phosphor, and the vacuum ultra violet （VUV） fluorescence spectroradiometric system （Zhejiang University Sensing Instruments Co. , Ltd. ） was used to measure the luminescent performance under 147 nm excitation. A scanning electron microscope （SEM） was used to identify the size and shape of the particles. X-ray diffraction （XRD） was used to confirm its crystalline structure. According to this study, the optimal after-treatment processes were as follows： milling time 5 min, milling medium 15 % C2 H5 OH, dispersal time 90 min and dispersal medium 15 % C2 Hs OH.展开更多
The synchronous construction of metal phosphate and phosphorus-doped carbon structures is of great significance to innovate the design,synthesis,and application of catalysts,as these phosphoruscontaining composite mat...The synchronous construction of metal phosphate and phosphorus-doped carbon structures is of great significance to innovate the design,synthesis,and application of catalysts,as these phosphoruscontaining composite materials have shown a remarkable contribution to electrocatalysts.However,their preparation procedure generally involves using large amounts of excess phosphorus sources for phosphorization,which inevitably release poisonous PH_(3) or dangerous phosphorus vapor.Here,a strategy for in-situ formation of FePO_(4) embedded in P-doped carbon 2D nano film(FePO_(4)/PdC)is developed using a highly integrated precursor,which is a small molecular organophosphine ligand,1,1’bis(diphenylphosphine)ferrocene(DPPF).The multi-source precursor DPPF that contains Fe,P,and C is molecular-vapor-deposited on the nickel foam(NF)supported ZIF-67 nanosheets to obtain the composite catalyst,namely DPPF-500/ZIF-67/NF.FePO_(4)/PdC encapsulated the ZIF-67 derived Co/N-doped carbon matrix(Co NC)to form a sandwich structure FePO_(4)/PdC@CoNC.The constructed catalyst shows good performance for OER,requiring an overpotential of only 297 m V to deliver 600 m A/cm^(2) with a Tafel slope of 42.7 m V dec^(-1).DFT calculations demonstrate that the synergistic effects between the metal active center and P-doped carbon film reduce the energy barriers and improve electron transport.This method of constructing P-containing catalysts overcomes the demand for additional P sources to realize eco-friendly fabrication and yields a unique structure with good catalytic activity.展开更多
Pretreatment of the carrier for supported catalysts can effectively improve the strong metal-support interaction(SMSI)and increase the dispersion of precious metals,which are critical to many important catalytic react...Pretreatment of the carrier for supported catalysts can effectively improve the strong metal-support interaction(SMSI)and increase the dispersion of precious metals,which are critical to many important catalytic reactions.In this work,we tuned SMSI on Pd/TiO_(2)catalysts through inducing surface defects of TiO_(2)by pretreated with different atmospheres(H_(2)/N_(2),N_(2),O_(2)/N_(2))at the high temperature(800℃).Multiple characterization results illustrated that surface defects anchored Pd species and thus enhanced their dispersion.During reduction,Ti^(3+)species formed and transferred onto the metallic Pd species and then induced SMSI,which effectively stabilize Pd species in the metallic state.The stronger MSI,the more stability of Pd species.As a case,Pd/TiO_(2)–800H_(2),with strongest MSI,displayed the best HCHO oxidation performance at low temperature(10℃).展开更多
The rapid increase in the aging population prompts the development of wearable devices and sophisticated robots. With their ability to collect complex information about their surroundings via e-skins, robots could per...The rapid increase in the aging population prompts the development of wearable devices and sophisticated robots. With their ability to collect complex information about their surroundings via e-skins, robots could perform more dynamic and variable tasks such as rescue missions or caring for the elderly. In this paper, we present a new concept of utilizing a very simple, highly flexible and stretchable capacitor sensor array, that can be attached on the surface of a retractable robot hand to realize three functions: determining the location, shape, and pressure of an object. This adaptive sensing system is accomplished using capacitors connected by aligned carbon nanotube(CNT) films constructed on an elastomer dielectric material, which can reduce the requirement on the accuracy of the machine vision system. This study has a very broad application in the manufacture of intelligent software robots.展开更多
This paper proposes a new mechanism to explain the performance of thin dye-sensitized solar cells （DSSC）. Near-stoichiometric flower-like Cu2ZnSnS4 （CZTS） microspheres with a high specific surface area was fabri- ...This paper proposes a new mechanism to explain the performance of thin dye-sensitized solar cells （DSSC）. Near-stoichiometric flower-like Cu2ZnSnS4 （CZTS） microspheres with a high specific surface area was fabri- cated for use as the photocathode in a DSSC. To improve the extraction and transfer of electrons, graphene was added to the CZTS. A DSSC with a 10-gin TiO2 pho- toanode layer exhibited a slightly degraded efficiency with a CZTS-graphene photocathode, relative to a Pt counter electrode （CE）. Nevertheless, when the thickness of the TiO2 photoanode was reduced to 2 lam, the efficiency of a DSSC with a CZTS-graphene photocathode was greater than that of a Pt-DSSC. It is speculated that, unlike the Pt CE, a CZTS-graphene photocathode not only collects electrons from an external circuit and catalyzes the reduction of the triiodide ions in the electrolyte, but also utilizes unabsorbed photons to produce photo-excited electrons and suppresses charge recombination, thus enhancing the performance of the cell. The use of narrowband gap p-type semiconductors as photocathodes offers a new means of fabricating thin dye-sensitized solar cells and effectively improving the cell performance.展开更多
Developing non-precious metal catalysts to selectively reduce functionalized nitroarenes with high efficiency is urgently desirable for the production of value-added amines.Herein,we report a novel,efficient,anti-pois...Developing non-precious metal catalysts to selectively reduce functionalized nitroarenes with high efficiency is urgently desirable for the production of value-added amines.Herein,we report a novel,efficient,anti-poisoning single-atom cobalt catalyst(Co-NAC)for the highly selective hydrogenation of the nitro to amino group for nitroarenes baring various functional groups,including vinyl,cyano,and halogen.Using a combination of structure characterization techniques,we have confirmed that the cobalt species are predominantly present in the form of four-coordinated Co single sites anchored on nitrogen-assembly carbon(NAC)as the ordered mesoporous support.Co-NAC catalysts enable the full conversion and>99%selectivity with molecular H2 as a green reductant under mild conditions(80℃,2 MPa H2).As for the selective hydrogenation of 3-nitrostyrene,Co-NAC catalyst affords high catalytic productivity(19.7 h-1),which is superior to the cobalt nanoparticles(NPs)catalysts and most of the recently reported Co-based catalysts.This is attributed to the highly accessible atomically-dispersed Co active sites,the high surface area with ordered-mesoporous morphology and the prominent high content of nitrogen dopants.Notably,Co-NAC catalyst displays resistance towards sulfur-containing poisons(20 equivalents)and strong non-oxidizing acid(8 M),showing great potential for continuous application in the chemical industry.展开更多
Organohalogen perovskites are attracting con- siderable attention for use in solar cells. However, the stability of these devices will determine whether they can be made commercially viable. Device encapsulation or th...Organohalogen perovskites are attracting con- siderable attention for use in solar cells. However, the stability of these devices will determine whether they can be made commercially viable. Device encapsulation or the use of a hydrophobic hole-transporting material can pre- vent the permeation of water into the perovskite layer and enhance the humidity stability of the cells under dark conditions. With regard to the light stability of solar cells, recent studies have yielded contradictory results. This work investigated the degradation mechanism of perovskite solar cells under illumination. Further, a simple method was proposed for improving their illumination stability. Amino acids were inserted between the compact TiO2 layer and the perovskite layer to effectively prevent the decomposition of the perovskite layer owing to the superoxide anions and hydroxyl radicals generated under illumination from the H2O and O2 adsorbed onto the TiO2 layer.展开更多
Hole transport layers(HTLs)play a significant role in the performance of perovskite solar cells.A new class of linear smallmolecules based on bis(4-methylthio)phenyl)amine as an end group,carbon,oxygen and sulfur as t...Hole transport layers(HTLs)play a significant role in the performance of perovskite solar cells.A new class of linear smallmolecules based on bis(4-methylthio)phenyl)amine as an end group,carbon,oxygen and sulfur as the center atoms for the center unit(denoted as MT-based small-molecule),respectively,have been applied as HTL,and two of them presented the efficiency over 20%in the planar inverted perovskite solar cells(PSCs),which demonstrated a significant improvement in comparison with the widely used HTL,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(known as PEDOT:PSS),in the planar inverted architecture.The ultrafast carrier dynamics show that the excited hot carrier cooling process of MT-based small-molecule HTL samples is faster than that of PEDOT:PSS samples.The kinetic analysis of photo-bleaching peaks of femtosecond transient absorption spectra reveals that the traps at the interface between MT-based small-molecule HTLs and MAPbI3 can be filled much quicker than that at PEDOT/MAPbI3 interfaces.Moreover,the hole injection time from MAPbI3 to MT-based small-molecule HTLs is around 10 times quicker than that to PEDOT:PSS.Such quick trap filling and hole extraction bring a significant enhancement in photovoltaic performances.These findings uncover the carrier transport mechanisms and illuminate a promising approach for the design of new HTLs for highly-efficient perovskite solar cells.展开更多
基金the National Natural Science Foundation of China(No.50475124)the Foundation for the Author of National Excellent Doctoral Dissertation of China(No.200330)New Century Excellent Talents in University(NCET-04-0515)
文摘The effect of annealing on microstructure, adhesive and frictional properties of GeSb2Te4 films were experimentally studied. The GeSb2Te4 films were prepared by radio frequency （RF） magnetron sputtering, and annealed at 200℃ and 340℃ under vacuum circumstance, respectively. The adhesion and friction experiments were mainly conducted with a lateral force microscope （LFM） for the GeSb2Te4 thin films before and after annealing. Their morphology and phase structure were analyzed by using atomic force microscopy （AFM） and X-ray Diffraction （XRD） techniques, and the nanoindention was employed to evaluate their hardness values. Moreover, an electric force microscope （EFM） was used to measure the surface potential. It is found that the deposited GeSb2Te4 thin film undergoes an amorphous-to-fcc and fcc-to-hex structure transition; the adhesion has a weaker dependence on the surface roughness, but a certain correlation with the surface potential of GeSb2Te4 thin films. And the friction behavior of GeSb2Te4 thin films follows their adhesion behavior under a lower applied load. However, such a relation is replaced by the mechanical behavior when the load is relatively higher. Moreover, the GeSb2Te4 thin film annealed at 340℃ presents a lubricative property.
基金National Natural Science Foundation of China(51335002)
文摘To further extend knowledge about the detailed knowledge on the crossflow characteristics in a multi-jets system under a confined space,particle image velocimetry (PIV) was employed to investigate the flow structures together with the distributions of the mean velocity components for Reynolds numbers (Re) ranging from 6 213 to 13 418,nozzle-to-plate spacing (H/D) varying from 0. 20 to1. 25,respectively. Results show that the crossflow configuration is significantly different from those of large nozzle-to-plate spacing. In addition,a turning point H/D=0.50 is revealed in the profile of the normalized maximum radial velocity which is associated with the heat transfer distribution on the impingement plate.
基金support from the National Natural Science Foundation of China(Grant Nos.21773218 and 61904166)。
文摘Achieving high-quality perovskite crystal films is a critical prerequisite in boosting solar cell efficiency and improving the device stability,but the delicate control of nucleation and growth of the perovskite film remains limited success.Herein,a facile but effective strategy has been developed to finely tailor the crystallization of thermally stable cesium/formamidinium(Cs/FA)based perovskite via partially replacing PbI2 with PbCl2 in the precursor solution.The incorporation of chlorine into the perovskite crystal lattice derived from PbCl2 changes the crystallization process and improves the crystal quality,which further results in the formation of larger crystal grains compared to the control sample.The larger crystal grains with high crystallinity lead to reduced grain boundaries,suppressed non-radiative recombination,and enhanced photoluminescence lifetime.Under the optimized conditions,the methylammonium free perovskite solar cells(PSCs)delivers a champion power conversion efficiency(PCE)of 21.30%with an open-circuit voltage as high as 1.18 V,which is one of the highest efficiencies for Cs/FA based PSCs up to now.Importantly,the unencapsulated PSC devices retain more than 95%and 81%of their original PCEs even after long-term(over one year)storage under ambient conditions or 2000 h’s thermal aging at 850C in a nitrogen atmosphere,respectively.
基金funded by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA17040506)the National Key Research and Development Program of China (2017YFA0204800/2016YFA0202403)+6 种基金the Key Program project of the National Natural Science Foundation of China (51933010)the National Natural Science Foundation of China (61974085)the 111 Project (B21005)the Changjiang Scholars and Innovative Research Team (IRT_14R33)the National University Research Fund (GK201903051)the Research Start-up Fund from Shaanxi Normal University (1110020142)the Shanxi Science and Technology Department (20201101012).
文摘Interface engineering is an effective way to improve efficiency and long-term stability of perovskite solar cells(PSCs).Herein,an ionic compound tetrabutylammonium hexafluorophosphate(TP6)is adopted to passivate surface defects of the perovskite film.It is found that TP6 effectively reduced the surface defects,especially at the grain boundaries where the defects are abundant.Meanwhile,the exposed long alkyl chains and fluorine atoms in the TP6 enhanced the moisture stability of the perovskite film due to its strong hydrophobicity.In addition,the driving force of charge carrier separation and transport is increased by enlarged built-in potential.Consequently,the power conversion efficiency(PCE)of PSCs is significantly improved from 20.59% to 22.41%by increased open-circuit voltage(V_(oc))and fill factor(FF).The unencapsulated device with TP6 treatment exhibits better stability than the control device,and the PCE retains-80%of its initial PCE after 30 days under 15%-25%relative humidity in storage,while the PCE of the control device declines by more than 50%.
基金Project(50475124)supported by the National Natural Science Foundation of ChinaProject(200330)supported by the Foundation for the National Excellent Doctoral Dissertation of ChinaProject(NCET-04-0515)supported by the New Century Excellent Talents in University,China
文摘GeSb2Te4 films were deposited on Si substrates by RF magnetron sputtering,and the effects of sputtering power on the surface topography and anti-compression properties were studied with atomic force microscope(AFM)and nanoindenter.Meanwhile,the mechanical properties of GeSb2Te4 films with oxygen impurity were also investigated.The results indicate that proper sputtering power is important for obtaining GeSb2Te4 films with high compact structure and low surface roughness,which present good load-support capacity.Although the effect of oxygen impurity on the anti-compression properties of GeSb2Te4 films is not very significant as a whole,certain oxygen dosage can relax the internal stress,thereby the hardness of the films drops slightly.
基金This paper is supported by the Excellent Young Teachers Sponsored Program of CUG(No . CUGQNL0530) .
文摘BaMgAl10 O17 ：Mn^2＋ green phosphor was prepared by high temperature solid state reaction and the optimal chemical formula is Ba0.85MgMn0.15Al11.993 B0.007 O19. The influences of milling and ultrasonic-dispersal on the luminescent properties, granularity and appearance of the phosphor were investigated, and the green phosphor with fine grain and uniform dispersion to be adapted to plasma display panels was obtained. A Hitachi F-4500 fluorescence spectrophotometer was used to measure the luminescent performance of the phosphor, and the vacuum ultra violet （VUV） fluorescence spectroradiometric system （Zhejiang University Sensing Instruments Co. , Ltd. ） was used to measure the luminescent performance under 147 nm excitation. A scanning electron microscope （SEM） was used to identify the size and shape of the particles. X-ray diffraction （XRD） was used to confirm its crystalline structure. According to this study, the optimal after-treatment processes were as follows： milling time 5 min, milling medium 15 % C2 H5 OH, dispersal time 90 min and dispersal medium 15 % C2 Hs OH.
基金financially supported by the National Natural Science Foundation of China(21872020)the 1226 Engineering Health Major Project(BWS17J028,AWS16J018)the Fundamental Research Funds for the Central Universities(N180705004)。
文摘The synchronous construction of metal phosphate and phosphorus-doped carbon structures is of great significance to innovate the design,synthesis,and application of catalysts,as these phosphoruscontaining composite materials have shown a remarkable contribution to electrocatalysts.However,their preparation procedure generally involves using large amounts of excess phosphorus sources for phosphorization,which inevitably release poisonous PH_(3) or dangerous phosphorus vapor.Here,a strategy for in-situ formation of FePO_(4) embedded in P-doped carbon 2D nano film(FePO_(4)/PdC)is developed using a highly integrated precursor,which is a small molecular organophosphine ligand,1,1’bis(diphenylphosphine)ferrocene(DPPF).The multi-source precursor DPPF that contains Fe,P,and C is molecular-vapor-deposited on the nickel foam(NF)supported ZIF-67 nanosheets to obtain the composite catalyst,namely DPPF-500/ZIF-67/NF.FePO_(4)/PdC encapsulated the ZIF-67 derived Co/N-doped carbon matrix(Co NC)to form a sandwich structure FePO_(4)/PdC@CoNC.The constructed catalyst shows good performance for OER,requiring an overpotential of only 297 m V to deliver 600 m A/cm^(2) with a Tafel slope of 42.7 m V dec^(-1).DFT calculations demonstrate that the synergistic effects between the metal active center and P-doped carbon film reduce the energy barriers and improve electron transport.This method of constructing P-containing catalysts overcomes the demand for additional P sources to realize eco-friendly fabrication and yields a unique structure with good catalytic activity.
基金supported by the Youth Innovation Promotion Association,CAS(No.2020310)the Science and Technology Planning Project of Xiamen City(No.3502Z20191021)the Science and Technology Innovation“2025”major program in Ningbo(No.2022Z028)。
文摘Pretreatment of the carrier for supported catalysts can effectively improve the strong metal-support interaction(SMSI)and increase the dispersion of precious metals,which are critical to many important catalytic reactions.In this work,we tuned SMSI on Pd/TiO_(2)catalysts through inducing surface defects of TiO_(2)by pretreated with different atmospheres(H_(2)/N_(2),N_(2),O_(2)/N_(2))at the high temperature(800℃).Multiple characterization results illustrated that surface defects anchored Pd species and thus enhanced their dispersion.During reduction,Ti^(3+)species formed and transferred onto the metallic Pd species and then induced SMSI,which effectively stabilize Pd species in the metallic state.The stronger MSI,the more stability of Pd species.As a case,Pd/TiO_(2)–800H_(2),with strongest MSI,displayed the best HCHO oxidation performance at low temperature(10℃).
基金supported by the National Key Research and Development Program of China(Grant No.2017YFB0307000-01)the National Natural Science Foundation of China(Grant No.91648109)the Priority Academic Program Development of Jiangsu Higher Education Institutions,333 Project of Jiangsu Province
文摘The rapid increase in the aging population prompts the development of wearable devices and sophisticated robots. With their ability to collect complex information about their surroundings via e-skins, robots could perform more dynamic and variable tasks such as rescue missions or caring for the elderly. In this paper, we present a new concept of utilizing a very simple, highly flexible and stretchable capacitor sensor array, that can be attached on the surface of a retractable robot hand to realize three functions: determining the location, shape, and pressure of an object. This adaptive sensing system is accomplished using capacitors connected by aligned carbon nanotube(CNT) films constructed on an elastomer dielectric material, which can reduce the requirement on the accuracy of the machine vision system. This study has a very broad application in the manufacture of intelligent software robots.
基金This work was supported by the National Natural Science Foundation of China （51272033, 51572037 and 51335002）, the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Natural Science Foundation of the Jiangsu Higher Education Institutions of China （14KJA430001）.
文摘This paper proposes a new mechanism to explain the performance of thin dye-sensitized solar cells （DSSC）. Near-stoichiometric flower-like Cu2ZnSnS4 （CZTS） microspheres with a high specific surface area was fabri- cated for use as the photocathode in a DSSC. To improve the extraction and transfer of electrons, graphene was added to the CZTS. A DSSC with a 10-gin TiO2 pho- toanode layer exhibited a slightly degraded efficiency with a CZTS-graphene photocathode, relative to a Pt counter electrode （CE）. Nevertheless, when the thickness of the TiO2 photoanode was reduced to 2 lam, the efficiency of a DSSC with a CZTS-graphene photocathode was greater than that of a Pt-DSSC. It is speculated that, unlike the Pt CE, a CZTS-graphene photocathode not only collects electrons from an external circuit and catalyzes the reduction of the triiodide ions in the electrolyte, but also utilizes unabsorbed photons to produce photo-excited electrons and suppresses charge recombination, thus enhancing the performance of the cell. The use of narrowband gap p-type semiconductors as photocathodes offers a new means of fabricating thin dye-sensitized solar cells and effectively improving the cell performance.
基金supported by the National Key R&D Program of China(No.2016YFA0202900)the National Natural Science Foundation of China(Nos.21878266,22078288,and 22108243)+4 种基金L.Q.and Y.T.L.were supported by the U.S.Department of Energy(DOE),Office of Basic Energy Sciences,Division of Chemical Sciences,Geosciences,and BiosciencesThe Ames Laboratory is operated for the U.S.DOE by Iowa State University under Contract No.DE-AC02-07CH11358W.Y.H.,J.Q.Y.,and X.W.thank the support from Iowa State University.F.D.L.thanks the Startup Fund from the University of Central Florida(UCF)S.H.X.thanks the support from the Preeminent Postdoctoral Program(P3)at UCFThis research used beamline 7-BM(QAS)of the National Synchrotron Light Source II,a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No.DE-SC0012704.
文摘Developing non-precious metal catalysts to selectively reduce functionalized nitroarenes with high efficiency is urgently desirable for the production of value-added amines.Herein,we report a novel,efficient,anti-poisoning single-atom cobalt catalyst(Co-NAC)for the highly selective hydrogenation of the nitro to amino group for nitroarenes baring various functional groups,including vinyl,cyano,and halogen.Using a combination of structure characterization techniques,we have confirmed that the cobalt species are predominantly present in the form of four-coordinated Co single sites anchored on nitrogen-assembly carbon(NAC)as the ordered mesoporous support.Co-NAC catalysts enable the full conversion and>99%selectivity with molecular H2 as a green reductant under mild conditions(80℃,2 MPa H2).As for the selective hydrogenation of 3-nitrostyrene,Co-NAC catalyst affords high catalytic productivity(19.7 h-1),which is superior to the cobalt nanoparticles(NPs)catalysts and most of the recently reported Co-based catalysts.This is attributed to the highly accessible atomically-dispersed Co active sites,the high surface area with ordered-mesoporous morphology and the prominent high content of nitrogen dopants.Notably,Co-NAC catalyst displays resistance towards sulfur-containing poisons(20 equivalents)and strong non-oxidizing acid(8 M),showing great potential for continuous application in the chemical industry.
文摘Organohalogen perovskites are attracting con- siderable attention for use in solar cells. However, the stability of these devices will determine whether they can be made commercially viable. Device encapsulation or the use of a hydrophobic hole-transporting material can pre- vent the permeation of water into the perovskite layer and enhance the humidity stability of the cells under dark conditions. With regard to the light stability of solar cells, recent studies have yielded contradictory results. This work investigated the degradation mechanism of perovskite solar cells under illumination. Further, a simple method was proposed for improving their illumination stability. Amino acids were inserted between the compact TiO2 layer and the perovskite layer to effectively prevent the decomposition of the perovskite layer owing to the superoxide anions and hydroxyl radicals generated under illumination from the H2O and O2 adsorbed onto the TiO2 layer.
基金supported by the National Key Research and Development Program of China(2017YFB037001)the National Natural Science Foundation of China(91648109、51603021、51602031、51673139)+2 种基金Jiangsu Provincial“333”High-level Talent Training Projectthe Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Applied Basic Research Program of Changzhou(CJ20190050)。
文摘Hole transport layers(HTLs)play a significant role in the performance of perovskite solar cells.A new class of linear smallmolecules based on bis(4-methylthio)phenyl)amine as an end group,carbon,oxygen and sulfur as the center atoms for the center unit(denoted as MT-based small-molecule),respectively,have been applied as HTL,and two of them presented the efficiency over 20%in the planar inverted perovskite solar cells(PSCs),which demonstrated a significant improvement in comparison with the widely used HTL,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(known as PEDOT:PSS),in the planar inverted architecture.The ultrafast carrier dynamics show that the excited hot carrier cooling process of MT-based small-molecule HTL samples is faster than that of PEDOT:PSS samples.The kinetic analysis of photo-bleaching peaks of femtosecond transient absorption spectra reveals that the traps at the interface between MT-based small-molecule HTLs and MAPbI3 can be filled much quicker than that at PEDOT/MAPbI3 interfaces.Moreover,the hole injection time from MAPbI3 to MT-based small-molecule HTLs is around 10 times quicker than that to PEDOT:PSS.Such quick trap filling and hole extraction bring a significant enhancement in photovoltaic performances.These findings uncover the carrier transport mechanisms and illuminate a promising approach for the design of new HTLs for highly-efficient perovskite solar cells.
