Step-scheme(S-scheme)heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier separation.The latter is critical in controlling the overall efficiency in one-step ph...Step-scheme(S-scheme)heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier separation.The latter is critical in controlling the overall efficiency in one-step photoexcitation systems.In this study,a nanosized BiVO4/Bi0.6Y0.4VO4 solid solution was prepared by a coprecipitation method following with hydrothermal or calcination processes.The S-scheme heterojunction was fabricated by in-situ pressure-induced transformations of bismuth vanadate from the tetragonal zircon phase to the monoclinic scheelite phase,which led to the formation of BiVO4 nanoparticles with a diameter of approximately 5 nm on the surface of BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4)/Bi_(0.6)Y_(0.4)VO_(4) with S-scheme heterojunctions showed significantly enhanced photocatalytic overall water splitting activity compared with using bare BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4).Characterization of the carrier dynamics demonstrated that a superior carrier separation through S-type heterojunctions might have caused the enhanced overall water splitting(OWS)activity.Surface photovoltage spectra and the results of selective photodeposition experiments indicated that the photogenerated holes mainly migrated to the BiVO4 nanoparticles in the heterojunction.This confirmed that the charge transfer route corresponds to an S-scheme rather than a type-II heterojunction mechanism under light illumination.This study presents a facile and efficient strategy to construct S-scheme heterojunctions through a pressure-induced phase transition.The results demonstrated that S-scheme junctions composed of different crystalline phases can boost the carrier separation capacity and eventually improve the photocatalytic OWS activity.展开更多
Membranes formed by polysulfonamide(PSA)and phosphotungstic acid(PWA)supported on nano-silica have been prepared.Fourier transform infrared spectra(FTIR)and thermogravimetric analysis(TGA)were used to characterize the...Membranes formed by polysulfonamide(PSA)and phosphotungstic acid(PWA)supported on nano-silica have been prepared.Fourier transform infrared spectra(FTIR)and thermogravimetric analysis(TGA)were used to characterize the structure and thermal properties of obtained membranes.The analyses of water uptake,proton conductivity and mechanical properties of the membranes revealed that PWA and silica produced a beneficial effect on proton conduction of the membranes.The membranes with 50 wt% of PWA-SiO2 /PSA were mechanically stable and gave proton conductivity of 2.57×10-2 S·cm-1 at 90℃ and 100% relative humidity.According to the obtained results,PWA and SiO2 doped PSA is a promising material for proton exchange membrane.展开更多
Stretchable color-changing fibers are urgently demanded for smart textiles/clothing due to their perfect implantability,permeability of vapor and heat,and flexibility/stretchability.Herein,stretchable electrothermochr...Stretchable color-changing fibers are urgently demanded for smart textiles/clothing due to their perfect implantability,permeability of vapor and heat,and flexibility/stretchability.Herein,stretchable electrothermochromic fibers were fabricated with unconventional stretchable conductive fibers as core layers and thermochromic coatings as shell layers.In the stretchable conductive fibers,hierarchical porous structures with percolative one-dimensional(1 D)conductive networks were constructed through phase inversion of carbon nanotube/polyurethane(CNT/PU)solutions.With the deposition of silver nanoparticles(AgN Ps)on the surface of micro-pores,electrically conductive dual-pathways consisting of0 D AgN Ps and 1 D CNTs were formed to significantly enhance the electric conductivity and thus improve the electrothermal performance of the fibers.More importantly,because of the connective CNTs and AgN Ps,such dual-pathways ensured the electron transport under the stretching state,preventing the sharp decay of conductivity and electrothermal performance.Through the continuous wet-spinning method,the stretchable conductive fibers can be easily obtained with the length up to several meters.At last,stretchable electrothermochromic fibers were prepared with two color-changing modes and implanted into textile perfectly,advancing their applications in wearable display and military adaptive camouflage of smart clothing.展开更多
The elastic conductor is crucial in wearable electronics and soft robotics.The ideal intrinsic elastic bulk conductors show uniform three-dimensional conductive networks and stable resistance during large stretch.A ch...The elastic conductor is crucial in wearable electronics and soft robotics.The ideal intrinsic elastic bulk conductors show uniform three-dimensional conductive networks and stable resistance during large stretch.A challenge is that the variation of resistance is high under deformation due to disconnection of conductive pathway for bulk elastic conductors.Our strategy is to introduce buckled structure into the conductive network,by self-assembly of a carbon nanotube layer on the interconnecting micropore surface of a prestrained foam,followed by strain relaxation.Both unfolding of buckles and flattening of micropores contributed to the stability of the resistance under deformation(2.0%resistance variation under 70%strain).Microstructural analysis and finite element analysis illustrated different patterns of two-dimensional buckling structures could be obtained due to the imperfections in the conductive layer.Applications as all-directional interconnects,stretchable electromagnetic interference shielding and electrothermal tumor ablation were demonstrated.展开更多
Ga-doped ZnO nanowires have been synthesized by a pulsed laser chemical vapor deposition method. The crystal structure and photoluminescence spectra indicate that the dopant atoms are well integrated into the ZnO wurt...Ga-doped ZnO nanowires have been synthesized by a pulsed laser chemical vapor deposition method. The crystal structure and photoluminescence spectra indicate that the dopant atoms are well integrated into the ZnO wurtzite lattice. The photocurrent properties at different temperatures have been systematically investigated for nanowires configured as a three-terminal device. Among the experimental highlights, a pronounced semiconductor-to-metal transition occurs upon UV band-to-band excitation. This is a consequence of the reduction in electron mobility arising from the drastically enhanced Coulomb interactions and surface scattering. Another feature is the reproducible presence of two resistance valleys at 220 and 320 K upon light irradiation. This phenomenon originates from the trapping and detrapping processes in the impurity band arising from the native defects as well as the extrinsic Ga dopants. This work demonstrates that due to the dimensional confinement in quasi-one-dimensional structures, enhanced Coulomb interaction, surface scattering, and impurity states can significantly influence charge transport.展开更多
文摘Step-scheme(S-scheme)heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier separation.The latter is critical in controlling the overall efficiency in one-step photoexcitation systems.In this study,a nanosized BiVO4/Bi0.6Y0.4VO4 solid solution was prepared by a coprecipitation method following with hydrothermal or calcination processes.The S-scheme heterojunction was fabricated by in-situ pressure-induced transformations of bismuth vanadate from the tetragonal zircon phase to the monoclinic scheelite phase,which led to the formation of BiVO4 nanoparticles with a diameter of approximately 5 nm on the surface of BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4)/Bi_(0.6)Y_(0.4)VO_(4) with S-scheme heterojunctions showed significantly enhanced photocatalytic overall water splitting activity compared with using bare BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4).Characterization of the carrier dynamics demonstrated that a superior carrier separation through S-type heterojunctions might have caused the enhanced overall water splitting(OWS)activity.Surface photovoltage spectra and the results of selective photodeposition experiments indicated that the photogenerated holes mainly migrated to the BiVO4 nanoparticles in the heterojunction.This confirmed that the charge transfer route corresponds to an S-scheme rather than a type-II heterojunction mechanism under light illumination.This study presents a facile and efficient strategy to construct S-scheme heterojunctions through a pressure-induced phase transition.The results demonstrated that S-scheme junctions composed of different crystalline phases can boost the carrier separation capacity and eventually improve the photocatalytic OWS activity.
文摘Membranes formed by polysulfonamide(PSA)and phosphotungstic acid(PWA)supported on nano-silica have been prepared.Fourier transform infrared spectra(FTIR)and thermogravimetric analysis(TGA)were used to characterize the structure and thermal properties of obtained membranes.The analyses of water uptake,proton conductivity and mechanical properties of the membranes revealed that PWA and silica produced a beneficial effect on proton conduction of the membranes.The membranes with 50 wt% of PWA-SiO2 /PSA were mechanically stable and gave proton conductivity of 2.57×10-2 S·cm-1 at 90℃ and 100% relative humidity.According to the obtained results,PWA and SiO2 doped PSA is a promising material for proton exchange membrane.
基金supported by the National Natural Science Foundation of China(51672043)Donghua University Distinguished Young Professor Program(LZB2019002)+1 种基金Young Elite Scientists Sponsorship Program by China Association for Science and Technology(2017QNRC001)the Fundamental Research Funds for the Central Universities(CUSF-DH-D-2018006)。
文摘Stretchable color-changing fibers are urgently demanded for smart textiles/clothing due to their perfect implantability,permeability of vapor and heat,and flexibility/stretchability.Herein,stretchable electrothermochromic fibers were fabricated with unconventional stretchable conductive fibers as core layers and thermochromic coatings as shell layers.In the stretchable conductive fibers,hierarchical porous structures with percolative one-dimensional(1 D)conductive networks were constructed through phase inversion of carbon nanotube/polyurethane(CNT/PU)solutions.With the deposition of silver nanoparticles(AgN Ps)on the surface of micro-pores,electrically conductive dual-pathways consisting of0 D AgN Ps and 1 D CNTs were formed to significantly enhance the electric conductivity and thus improve the electrothermal performance of the fibers.More importantly,because of the connective CNTs and AgN Ps,such dual-pathways ensured the electron transport under the stretching state,preventing the sharp decay of conductivity and electrothermal performance.Through the continuous wet-spinning method,the stretchable conductive fibers can be easily obtained with the length up to several meters.At last,stretchable electrothermochromic fibers were prepared with two color-changing modes and implanted into textile perfectly,advancing their applications in wearable display and military adaptive camouflage of smart clothing.
基金supported by the National Key Research and Development Program of China(2017YFB0307000)the National Natural Science Foundation of China(51973093,U1533122 and 51773094)+5 种基金the Natural Science Foundation of Tianjin(18JCZDJC36800)the Science Foundation for Distinguished Young Scholars of Tianjin(18JCJQJC46600)the Fundamental Research Funds for the Central Universities(63171219)the State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University(LK1704)the National Special Support Plan for High-level Talents people(C041800902)the Eugene McDermott Graduate Fellows Program。
文摘The elastic conductor is crucial in wearable electronics and soft robotics.The ideal intrinsic elastic bulk conductors show uniform three-dimensional conductive networks and stable resistance during large stretch.A challenge is that the variation of resistance is high under deformation due to disconnection of conductive pathway for bulk elastic conductors.Our strategy is to introduce buckled structure into the conductive network,by self-assembly of a carbon nanotube layer on the interconnecting micropore surface of a prestrained foam,followed by strain relaxation.Both unfolding of buckles and flattening of micropores contributed to the stability of the resistance under deformation(2.0%resistance variation under 70%strain).Microstructural analysis and finite element analysis illustrated different patterns of two-dimensional buckling structures could be obtained due to the imperfections in the conductive layer.Applications as all-directional interconnects,stretchable electromagnetic interference shielding and electrothermal tumor ablation were demonstrated.
文摘Ga-doped ZnO nanowires have been synthesized by a pulsed laser chemical vapor deposition method. The crystal structure and photoluminescence spectra indicate that the dopant atoms are well integrated into the ZnO wurtzite lattice. The photocurrent properties at different temperatures have been systematically investigated for nanowires configured as a three-terminal device. Among the experimental highlights, a pronounced semiconductor-to-metal transition occurs upon UV band-to-band excitation. This is a consequence of the reduction in electron mobility arising from the drastically enhanced Coulomb interactions and surface scattering. Another feature is the reproducible presence of two resistance valleys at 220 and 320 K upon light irradiation. This phenomenon originates from the trapping and detrapping processes in the impurity band arising from the native defects as well as the extrinsic Ga dopants. This work demonstrates that due to the dimensional confinement in quasi-one-dimensional structures, enhanced Coulomb interaction, surface scattering, and impurity states can significantly influence charge transport.
