All-solid-state Z-scheme photocatalysts for overall water splitting to evolve H_(2) is a promising strategy for efficient conversion of solar energy.However,most of these strategies require redox mediators.Herein,a di...All-solid-state Z-scheme photocatalysts for overall water splitting to evolve H_(2) is a promising strategy for efficient conversion of solar energy.However,most of these strategies require redox mediators.Herein,a direct Z-scheme photoelectrocatalytic electrode based on a WO_(3-x)nanowire-bridged TiO_(2)nanorod array heterojunction is constructed for overall water splitting,producing H_(2).The as-prepared WO_(3-x)/TiO_(2)nanorod array heterojunction shows photoelectrochemical(PEC)overall water splitting activity evolving both H_(2) and O_(2)under UV-vis light irradiation.An optimum PEC activity was achieved over a 1.67-WO_(3-x)/TiO_(2)photoelectrode yielding maximum H_(2) and O_(2)evolution rates roughly 11 times higher than that of pure TiO_(2)nanorods without any sacrificial agent or redox mediator.The role of oxygen vacancy in WO_(3-x)in affecting the H_(2) production rate was also comprehensively studied.The superior PEC activity of the WO_(3-x)/TiO_(2)electrode for overall water splitting can be ascribed to an efficient Z-scheme charge transfer pathway between the WO_(3-x)nanowires and TiO_(2)nanorods,the presence of oxygen vacancies in WO_(3-x),and a bias potential applied on the photoelectrode,resulting in effective spatial charge separation.This study provides a novel strategy for developing highly efficient PECs for overall water splitting.展开更多
1T phase MoS_(2)(1T-MoS_(2)) is a promising substitute of platinum electrocatalyst for hydrogen evolution reaction(HER)due to its high intrinsic activity but suffering from thermodynamical instability.Although great e...1T phase MoS_(2)(1T-MoS_(2)) is a promising substitute of platinum electrocatalyst for hydrogen evolution reaction(HER)due to its high intrinsic activity but suffering from thermodynamical instability.Although great efforts have been made to synthesize 1T-MoS_(2) and enhance its stability,it remains a big challenge to realize the phase control and stabilization of 1T-MoS_(2).Herein,based on crystal field theory analysis,we propose a new solution by designing an electrocatalyst of 1T-MoS_(2) nanosheets anchoring on black TiO2-xnanotube arrays in-situ grown on Ti plate(1T-MoS_(2)/TiO_(2-x)@Ti).The black TiO_(2-x)substrate is expected to play as electron donors to increase the charge in Mo 4 d orbits of 1T-MoS_(2) and thus weaken the asymmetric occupation of electrons in the Mo 4 d orbits.Experimental results demonstrate that black TiO_(2-x)nanotubes shift electrons to MoS_(2) and induce MoS_(2) to generate more 1 T phase due to stabilizing the 1T-MoS_(2) nanosheets compared with a Ti substrate.Thus 1T-MoS_(2/)TiO_(2-x)@Ti shows much improved HER performance with a small Tafel slope of 42 m V dec^(-1) and excellent catalytic stability with negligible degradation for 24 h.Theoretical calculations confirm that the black TiO_(2-x)substrate can effectively stabilize metastable 1T-MoS_(2) due to electrons transferring from black TiO_(2-x)to Mo 4 d orbits.This work sheds light on the instability of 1T-MoS_(2) and provides an essential method to stabilize and efficiently utilize 1T-MoS_(2) for HER.展开更多
The increase in energy consumption and its collateral damage on the environment has encouraged the development of environment-friendly ceramic materials with good energy storage properties.In this work,(1-x)Na_(0.5)Bi...The increase in energy consumption and its collateral damage on the environment has encouraged the development of environment-friendly ceramic materials with good energy storage properties.In this work,(1-x)Na_(0.5)Bi_(0.5)TiO_(3)-xCa(Mg_(1/3)Nb_(2/3))O_(3) ceramics were synthesized by the solid-state reaction method.The 0.88Na_(0.5)Bi_(0.5)TiO_(3)-0.12Ca(Mg_(1/3)Nb_(2/3))O_(3) ceramic exhibited a high recoverable energy storage density of 8.1 J/cm3 and energy storage efficiency of 82.4% at 550 kV/cm.The introduction of Ca(Mg_(1/3)Nb_(2/3))O_(3) reduced the grain size and increased the band gap,thereby enhancing the breakdown field strength of the ceramic materials.The method also resulted in good temperature stability(20–140℃),frequency stability(1–200 Hz),and fatigue stability over 10^(6) cycles.In addition,an ultrahigh power density of 187 MW/cm^(3) and a fast charge-discharge rate(t_(0.9)=57.2 ns)can be obtained simultaneously.Finite element method analysis revealed that the decrease of grain size was beneficial to the increase of breakdown field strength.Therefore,the 0.88Na_(0.5)Bi_(0.5)TiO_(3)-0.12Ca(Mg_(1/3)Nb_(2/3))O_(3) ceramics resulted in high energy storage properties with good stability and were promising environment-friendly materials for advanced pulsed power systems applications.展开更多
Semiconductor-molecule surface-enhanced Raman scattering(SERS),especially the stronger interfacial charge transfer process(ICTP),represents a frontier in the field of SERS with spectral reproducibility and unparallele...Semiconductor-molecule surface-enhanced Raman scattering(SERS),especially the stronger interfacial charge transfer process(ICTP),represents a frontier in the field of SERS with spectral reproducibility and unparalleled selectivity.Herein,through a laser microfabrication method in situ,the free-standing,super hydrophilic and vacancy-rich TiO_(2-x)/Ti is successfully synthesized.Using blue TiO_(x)/Ti(B-TiO_(x)/Ti)as preconcentrated substrate,a nanomolar-level limit of detection of 12 nmol/L at 1385 cm–1,is confirmed using crystal violet(CV)bacteriostat as a model under 532 nm excitation.Furthermore,the results demonstrate that the SERS enhancement mechanism is via the moderate adulteration of oxygen vacancy,which leads to a narrow value of band gap and increases the ICTP of substrate to molecules.Using a hand-held extractor assembled with B-TiO_(x)/Ti microfiber,the operando analysis of mixtures distributed information excited in different parts of Asian carp is facilely achieved.This work guides the controlled synthesis of vacancy-rich TiO_(2-x)/Ti nanostructure and its application in ultrasensitive extraction-SERS detection.It also provides the direction for the rapid and operando transmission of biological information with temporal and spatial concentration distribution in human tissues by highly sensitized materials.展开更多
The remarkable contribution of oxygen vacancies has been revealed by the operando spectroscopies for methanol synthesis from CO_(2)hydrogeneration on the reducible metal oxide-supported copper catalysts.However,a chal...The remarkable contribution of oxygen vacancies has been revealed by the operando spectroscopies for methanol synthesis from CO_(2)hydrogeneration on the reducible metal oxide-supported copper catalysts.However,a challenge remains in the intrinsic understanding of the evolution and advantage of oxygen vacancies for methanol synthesis.Here we prepare the TiO_(2–x)/Cu with different oxygen vacancy densities by adjusting the ball-milling frequency.At the optimal condition,a TiO_(2–x)/Cu with more oxygen vacancies delivers an excellent methanol yield of 26.5 mmol g^(-1)h^(-1)at 300℃with a selectivity of more than 70%.The combined analysis of experimental characterizations and theoretical calculations reveals that the mutual dispersions of TiO_(2–x)and Cu driven by mechanical energy induce the electron rearrangement in the d orbital of the Ti atom and relax the Ti–O binding at the interface,which facilitates the formation of oxygen vacancies that further reduce the barrier of CO_(2)hydrogenation to^(*)HCOO due to higher nucleophilicity of titanium ions.展开更多
We present the work about the initiative fabrication of multi-scale hierarchical TiO2-x by our strategy,combining high pressure and high temperature(HPHT)reactive sintering with appropriate ratio of coarse Ti to nanos...We present the work about the initiative fabrication of multi-scale hierarchical TiO2-x by our strategy,combining high pressure and high temperature(HPHT)reactive sintering with appropriate ratio of coarse Ti to nanosized TiO_(2).Ubiquitous lattice defects engineering has also been achieved in our samples by HPHT.The thermoelectric performance was significantly enhanced,and rather low thermal conductivity(1.60 W m^(-1)K^(-1))for titanium oxide was reported here for TiO1.76.Correspondingly,a high dimensionless figure of merit(zT)up to 0.33 at 700℃was realized in it.As far as we know,this value is an enhancement of 43%of the ever best result about nonstoichiometric TiO_(2)and the result is also exciting for oxide thermoelectric materials.The moderate power factor,the significantly reduced thermal conductivity and the remarkable synergy between electrical properties and thermal conductivity are responsible for the excellent thermoelectric performance.We develop a facile strategy for preparing multi-scale hierarchical TiO_(2-x)and its superior ability to optimize thermoelectric performance has been demonstrated here.展开更多
Perovskite-type lithium lanthanum titanates(LLTO)display a high bulk ionic conductivity and are considered a promising electrolyte for building up to advanced solid-state Li-ion batteries.The LLTO crystals contain a h...Perovskite-type lithium lanthanum titanates(LLTO)display a high bulk ionic conductivity and are considered a promising electrolyte for building up to advanced solid-state Li-ion batteries.The LLTO crystals contain a high concentration of intrinsically formed 90ο-rotated domain boundaries(DBs)serving as barriers to bulk Li-ion conduction.However,the mechanism of how the DB concentration and DB resistance can compete with each other to determine the bulk conductivity of LLTO is still unknown.Here we report a comprehensive study of LLTO compounds,aimed to unravel the mechanism and hence explore new path(s)for further improving the conductivity of this material.Our results show that both the sintering temperature and chemical composition can affect significantly the domain structures in LLTO.It is found that a decrease in the DB concentration is always accompanied by increased DB resistance due to the increased lattice mismatch at DBs,and vice versa.By unifying the electrochemical impedance spectroscopy and transmission electron microscopy analysis,it is clearly shown that the high DB resistance,instead of DB concentration,acts as the dominant factor governing the bulk conductivity of LLTO.The results thus renew the conventional understanding of the bulk Li-ion conduction in LLTO and shed light on developing novel LLTO electrolyte materials with improved ionic conductivity.展开更多
Research on doping modification of ZnTiO_(3) ceramics to enhance microwave dielectric properties has been hindered by poor performance,unclear structure-function mechanisms.To expand the applicability of ZnTiO_(3) cer...Research on doping modification of ZnTiO_(3) ceramics to enhance microwave dielectric properties has been hindered by poor performance,unclear structure-function mechanisms.To expand the applicability of ZnTiO_(3) ceramics,this study explores Zn_(1-x)Li_(2x)TiO_(3)(O≤×≤1)ceramics using a phase engineering strategy.Our findings reveal that the introduction of Lit into the ZnTiO_(3) system initiates a multiple phase transition,starting at x=0.1.Initially,ilmenite ZnTiO_(3) transforms into a cubic ordered spinel phase(space group P4332).Subsequently,a transition to a disordered spinel phase(space group Fd3m)occurs at x=0.5,culminating in the formation of a monoclinic rock salt-structured LizTiO3 phase.Significantly,two sets of ceramics with near-zero temperature coefficients of resonance frequency(t:)were obtained at x=0.1 and 0.75.Moreover,the quality factor(Qxf)demonstrated a 4.4-fold increase compared to that of ZnTiO_(3) ceramics at x=0.25(105,013 GHz).Additionally,it was observed that the Ti4 polarization in Zn_(1-x)Li_(2x)TiO_(3) ceramics was underestimated by 11.3%-13.3%,causing the measured dielectric constant(e.)exceeding the theoretical dielectric constant(eth).The ionic polarizability of Ti*was adjusted to stabilize around 3.29 A.Evaluation using multiple methods,including Phillips-van Vechten-Levine(P-V-L)theory,Raman vibrational mode analysis,bond valence,bond energy theory,and octahedral distortion,confirms that the Ti-O bonds within the octahedron predominantly affect&r,the increasing lattice energy(U)contributes to the enhancement of Qxf,and the strengthened Li-O bond energy effectively regulates Tr.展开更多
Defects can strongly affect the lattice,strain,and electronic structures of nanomaterials photocatalysts,like a double-edged sword of both positive significance and negative influence on photocatalytic performances.To...Defects can strongly affect the lattice,strain,and electronic structures of nanomaterials photocatalysts,like a double-edged sword of both positive significance and negative influence on photocatalytic performances.To date,most studies into defects only partially elucidated their beneficial or detrimental roles in photocatalysis.However,a quantitative understanding of the photocatalytic performances modulated by defect concentration still needs to be discovered.Here,a series of TiO_(2-X)mesoporous spheres(MS)with different oxygen vacancy concentrations for photocatalytic applications were prepared by hightemperature chemical reduction.The link between oxygen vacancy concentration and photocatalytic performance was successfully established.The localization of carriers dominated by the Stark effect is first enhanced and then weakened with increasing oxygen vacancy concentration,which is a crucial factor in explaining the double-edged sword role of defect concentration in photocatalysis.As the reduction temperature rises to 300℃,carrier localization dominated by the quantum-confined Stark effect maximizes the separation ability of photo generated electron hole pairs,thus exhibiting the best catalytic performance for photocatalytic hydrogen production and the degradation of organic pollutants,as demonstrated by a hydrogen evolution rate of 523.7μmol g^(-1)h^(-1)and a ninefold higher RhB photodegradation rate compared to TiO_(2)MS.The work offers excellent flexibility for precisely constructing high-performance photocatalysts by understanding vacancy engineering.展开更多
Near-infrared(NIR)-light-triggered nanomedicine, including photodynamic therapy(PDT)and photothermal therapy(PTT), is growing an attractive approach for cancer therapy due to its high spatiotemporal controllability an...Near-infrared(NIR)-light-triggered nanomedicine, including photodynamic therapy(PDT)and photothermal therapy(PTT), is growing an attractive approach for cancer therapy due to its high spatiotemporal controllability and minimal invasion, but the tumor eradication is limited by the intrinsic anti-stress response of tumor cells. Herein, we fabricate a tumor-microenvironment responsive CRISPR nanoplatform based on oxygen-deficient titania(TiO_(2-x)) for mild NIR-phototherapy. In tumor microenvironment, the overexpressed hyaluronidase(HAase) and glutathione(GSH) can readily destroy hyaluronic acid(HA) and disulfide bond and releases the Cas9/sgRNA from TiO_(2-x) to target the stress alleviating regulators, i.e., nuclear factor E2-related factor 2(NRF2) and heat shock protein 90a(HSP90a), thereby reducing the stress tolerance of tumor cells. Under subsequent NIR light illumination, the TiO_(2-x) demonstrates a higher anticancer effect both in vitro and in vivo. This strategy not only provides a promising modality to kills cancer cells in a minimal side-effects manner by interrupting anti-stress pathways but also proposes a general approach to achieve controllable gene editing in tumor region without unwanted genetic mutation in normal environments.展开更多
基金supported by the National Key Research and Development Program of China(2019YFA0705400 and 2019YFD0901100)the National Natural Science Foundation of China(21991151,21925404,and 21775127)+1 种基金the“111”Project(B17027)Guangdong Basic and Applied Basic Research Foundation(2020A1515010510)。
文摘All-solid-state Z-scheme photocatalysts for overall water splitting to evolve H_(2) is a promising strategy for efficient conversion of solar energy.However,most of these strategies require redox mediators.Herein,a direct Z-scheme photoelectrocatalytic electrode based on a WO_(3-x)nanowire-bridged TiO_(2)nanorod array heterojunction is constructed for overall water splitting,producing H_(2).The as-prepared WO_(3-x)/TiO_(2)nanorod array heterojunction shows photoelectrochemical(PEC)overall water splitting activity evolving both H_(2) and O_(2)under UV-vis light irradiation.An optimum PEC activity was achieved over a 1.67-WO_(3-x)/TiO_(2)photoelectrode yielding maximum H_(2) and O_(2)evolution rates roughly 11 times higher than that of pure TiO_(2)nanorods without any sacrificial agent or redox mediator.The role of oxygen vacancy in WO_(3-x)in affecting the H_(2) production rate was also comprehensively studied.The superior PEC activity of the WO_(3-x)/TiO_(2)electrode for overall water splitting can be ascribed to an efficient Z-scheme charge transfer pathway between the WO_(3-x)nanowires and TiO_(2)nanorods,the presence of oxygen vacancies in WO_(3-x),and a bias potential applied on the photoelectrode,resulting in effective spatial charge separation.This study provides a novel strategy for developing highly efficient PECs for overall water splitting.
基金supported by the New Zealand China Doctoral Research Scholarship (Grant no. 201706080124)support from the China Scholarships Council (CSC) for his study at the University of Auckland
文摘1T phase MoS_(2)(1T-MoS_(2)) is a promising substitute of platinum electrocatalyst for hydrogen evolution reaction(HER)due to its high intrinsic activity but suffering from thermodynamical instability.Although great efforts have been made to synthesize 1T-MoS_(2) and enhance its stability,it remains a big challenge to realize the phase control and stabilization of 1T-MoS_(2).Herein,based on crystal field theory analysis,we propose a new solution by designing an electrocatalyst of 1T-MoS_(2) nanosheets anchoring on black TiO2-xnanotube arrays in-situ grown on Ti plate(1T-MoS_(2)/TiO_(2-x)@Ti).The black TiO_(2-x)substrate is expected to play as electron donors to increase the charge in Mo 4 d orbits of 1T-MoS_(2) and thus weaken the asymmetric occupation of electrons in the Mo 4 d orbits.Experimental results demonstrate that black TiO_(2-x)nanotubes shift electrons to MoS_(2) and induce MoS_(2) to generate more 1 T phase due to stabilizing the 1T-MoS_(2) nanosheets compared with a Ti substrate.Thus 1T-MoS_(2/)TiO_(2-x)@Ti shows much improved HER performance with a small Tafel slope of 42 m V dec^(-1) and excellent catalytic stability with negligible degradation for 24 h.Theoretical calculations confirm that the black TiO_(2-x)substrate can effectively stabilize metastable 1T-MoS_(2) due to electrons transferring from black TiO_(2-x)to Mo 4 d orbits.This work sheds light on the instability of 1T-MoS_(2) and provides an essential method to stabilize and efficiently utilize 1T-MoS_(2) for HER.
基金This work is supported by the Natural Science Foundation of Shandong Province of China(Nos.ZR2020ME035,ZR2020QE043 and ZR2020QE044)National Natural Science Foundation of China(Nos.51872166 and 52102132)+1 种基金Postdoctoral Research Foundation of China(2017M622196)Opening Project of Key Laboratory of Inorganic Functional Materials and Devices,Chinese Academy of Sciences(KLIFMD201705).
文摘The increase in energy consumption and its collateral damage on the environment has encouraged the development of environment-friendly ceramic materials with good energy storage properties.In this work,(1-x)Na_(0.5)Bi_(0.5)TiO_(3)-xCa(Mg_(1/3)Nb_(2/3))O_(3) ceramics were synthesized by the solid-state reaction method.The 0.88Na_(0.5)Bi_(0.5)TiO_(3)-0.12Ca(Mg_(1/3)Nb_(2/3))O_(3) ceramic exhibited a high recoverable energy storage density of 8.1 J/cm3 and energy storage efficiency of 82.4% at 550 kV/cm.The introduction of Ca(Mg_(1/3)Nb_(2/3))O_(3) reduced the grain size and increased the band gap,thereby enhancing the breakdown field strength of the ceramic materials.The method also resulted in good temperature stability(20–140℃),frequency stability(1–200 Hz),and fatigue stability over 10^(6) cycles.In addition,an ultrahigh power density of 187 MW/cm^(3) and a fast charge-discharge rate(t_(0.9)=57.2 ns)can be obtained simultaneously.Finite element method analysis revealed that the decrease of grain size was beneficial to the increase of breakdown field strength.Therefore,the 0.88Na_(0.5)Bi_(0.5)TiO_(3)-0.12Ca(Mg_(1/3)Nb_(2/3))O_(3) ceramics resulted in high energy storage properties with good stability and were promising environment-friendly materials for advanced pulsed power systems applications.
基金supported by National Key Research and Development Program of China(No.2023YFB3210400)Major Scientific and Technological Innovation Project of Shandong Province(No.2021CXGC010603)+1 种基金Natural Science Foundation of Shandong Province(Nos.ZR2020QE057,ZR2020QE071,ZR2020LLZ006)Innovative Team Project of Jinan(No.2021GXRC019)。
文摘Semiconductor-molecule surface-enhanced Raman scattering(SERS),especially the stronger interfacial charge transfer process(ICTP),represents a frontier in the field of SERS with spectral reproducibility and unparalleled selectivity.Herein,through a laser microfabrication method in situ,the free-standing,super hydrophilic and vacancy-rich TiO_(2-x)/Ti is successfully synthesized.Using blue TiO_(x)/Ti(B-TiO_(x)/Ti)as preconcentrated substrate,a nanomolar-level limit of detection of 12 nmol/L at 1385 cm–1,is confirmed using crystal violet(CV)bacteriostat as a model under 532 nm excitation.Furthermore,the results demonstrate that the SERS enhancement mechanism is via the moderate adulteration of oxygen vacancy,which leads to a narrow value of band gap and increases the ICTP of substrate to molecules.Using a hand-held extractor assembled with B-TiO_(x)/Ti microfiber,the operando analysis of mixtures distributed information excited in different parts of Asian carp is facilely achieved.This work guides the controlled synthesis of vacancy-rich TiO_(2-x)/Ti nanostructure and its application in ultrasensitive extraction-SERS detection.It also provides the direction for the rapid and operando transmission of biological information with temporal and spatial concentration distribution in human tissues by highly sensitized materials.
基金supported by National Key Research and Development Program of China(2022YFE0128600,2023YFA1508103)National Natural Science Foundation of China(22278365)+1 种基金Natural Science Foundation of Zhejiang Province(LR22B060002)the grant from ShanxiZheda Institue of Advanced Materials and Chemical Engineering(2021STAT-002)。
文摘The remarkable contribution of oxygen vacancies has been revealed by the operando spectroscopies for methanol synthesis from CO_(2)hydrogeneration on the reducible metal oxide-supported copper catalysts.However,a challenge remains in the intrinsic understanding of the evolution and advantage of oxygen vacancies for methanol synthesis.Here we prepare the TiO_(2–x)/Cu with different oxygen vacancy densities by adjusting the ball-milling frequency.At the optimal condition,a TiO_(2–x)/Cu with more oxygen vacancies delivers an excellent methanol yield of 26.5 mmol g^(-1)h^(-1)at 300℃with a selectivity of more than 70%.The combined analysis of experimental characterizations and theoretical calculations reveals that the mutual dispersions of TiO_(2–x)and Cu driven by mechanical energy induce the electron rearrangement in the d orbital of the Ti atom and relax the Ti–O binding at the interface,which facilitates the formation of oxygen vacancies that further reduce the barrier of CO_(2)hydrogenation to^(*)HCOO due to higher nucleophilicity of titanium ions.
基金Program for Innovation Talents in University of Liaoning Province (LR2019044)Natural Science Foundation of Liaoning Province of China (2019-ZD-0540)+1 种基金Program for Young and Middle-aged Innovation Talents in Science and Technologies of Shenyang (RC190359)Project of Guangxi Key Laboratory of Information Materials (Guilin University of Electronic Technology),China (191007-K)。
基金This work was supported by the National Natural Science Foundation of China(Grant No.51171070)the Project of Jilin Science and Technology Development Plan(20170101045JC)Graduate Innovation Fund of Jilin University(Project No.2016065).
文摘We present the work about the initiative fabrication of multi-scale hierarchical TiO2-x by our strategy,combining high pressure and high temperature(HPHT)reactive sintering with appropriate ratio of coarse Ti to nanosized TiO_(2).Ubiquitous lattice defects engineering has also been achieved in our samples by HPHT.The thermoelectric performance was significantly enhanced,and rather low thermal conductivity(1.60 W m^(-1)K^(-1))for titanium oxide was reported here for TiO1.76.Correspondingly,a high dimensionless figure of merit(zT)up to 0.33 at 700℃was realized in it.As far as we know,this value is an enhancement of 43%of the ever best result about nonstoichiometric TiO_(2)and the result is also exciting for oxide thermoelectric materials.The moderate power factor,the significantly reduced thermal conductivity and the remarkable synergy between electrical properties and thermal conductivity are responsible for the excellent thermoelectric performance.We develop a facile strategy for preparing multi-scale hierarchical TiO_(2-x)and its superior ability to optimize thermoelectric performance has been demonstrated here.
基金supported by the National Natural Science Foundation of China(22075003,U2030206)。
文摘Perovskite-type lithium lanthanum titanates(LLTO)display a high bulk ionic conductivity and are considered a promising electrolyte for building up to advanced solid-state Li-ion batteries.The LLTO crystals contain a high concentration of intrinsically formed 90ο-rotated domain boundaries(DBs)serving as barriers to bulk Li-ion conduction.However,the mechanism of how the DB concentration and DB resistance can compete with each other to determine the bulk conductivity of LLTO is still unknown.Here we report a comprehensive study of LLTO compounds,aimed to unravel the mechanism and hence explore new path(s)for further improving the conductivity of this material.Our results show that both the sintering temperature and chemical composition can affect significantly the domain structures in LLTO.It is found that a decrease in the DB concentration is always accompanied by increased DB resistance due to the increased lattice mismatch at DBs,and vice versa.By unifying the electrochemical impedance spectroscopy and transmission electron microscopy analysis,it is clearly shown that the high DB resistance,instead of DB concentration,acts as the dominant factor governing the bulk conductivity of LLTO.The results thus renew the conventional understanding of the bulk Li-ion conduction in LLTO and shed light on developing novel LLTO electrolyte materials with improved ionic conductivity.
基金This work was supported by the National Natural Science Foundation of China(No.52102129)the Hunan Provincial Natural Science Foundation of China(No.2023JJ30138)the science and technology innovation Program of Hunan Province(No.2023RC3094).
文摘Research on doping modification of ZnTiO_(3) ceramics to enhance microwave dielectric properties has been hindered by poor performance,unclear structure-function mechanisms.To expand the applicability of ZnTiO_(3) ceramics,this study explores Zn_(1-x)Li_(2x)TiO_(3)(O≤×≤1)ceramics using a phase engineering strategy.Our findings reveal that the introduction of Lit into the ZnTiO_(3) system initiates a multiple phase transition,starting at x=0.1.Initially,ilmenite ZnTiO_(3) transforms into a cubic ordered spinel phase(space group P4332).Subsequently,a transition to a disordered spinel phase(space group Fd3m)occurs at x=0.5,culminating in the formation of a monoclinic rock salt-structured LizTiO3 phase.Significantly,two sets of ceramics with near-zero temperature coefficients of resonance frequency(t:)were obtained at x=0.1 and 0.75.Moreover,the quality factor(Qxf)demonstrated a 4.4-fold increase compared to that of ZnTiO_(3) ceramics at x=0.25(105,013 GHz).Additionally,it was observed that the Ti4 polarization in Zn_(1-x)Li_(2x)TiO_(3) ceramics was underestimated by 11.3%-13.3%,causing the measured dielectric constant(e.)exceeding the theoretical dielectric constant(eth).The ionic polarizability of Ti*was adjusted to stabilize around 3.29 A.Evaluation using multiple methods,including Phillips-van Vechten-Levine(P-V-L)theory,Raman vibrational mode analysis,bond valence,bond energy theory,and octahedral distortion,confirms that the Ti-O bonds within the octahedron predominantly affect&r,the increasing lattice energy(U)contributes to the enhancement of Qxf,and the strengthened Li-O bond energy effectively regulates Tr.
基金supported by the National Key Research and Development Program of China,(No.2019YFA0705201)the National Natural Science Foundation of China(No.U2032129)。
文摘Defects can strongly affect the lattice,strain,and electronic structures of nanomaterials photocatalysts,like a double-edged sword of both positive significance and negative influence on photocatalytic performances.To date,most studies into defects only partially elucidated their beneficial or detrimental roles in photocatalysis.However,a quantitative understanding of the photocatalytic performances modulated by defect concentration still needs to be discovered.Here,a series of TiO_(2-X)mesoporous spheres(MS)with different oxygen vacancy concentrations for photocatalytic applications were prepared by hightemperature chemical reduction.The link between oxygen vacancy concentration and photocatalytic performance was successfully established.The localization of carriers dominated by the Stark effect is first enhanced and then weakened with increasing oxygen vacancy concentration,which is a crucial factor in explaining the double-edged sword role of defect concentration in photocatalysis.As the reduction temperature rises to 300℃,carrier localization dominated by the quantum-confined Stark effect maximizes the separation ability of photo generated electron hole pairs,thus exhibiting the best catalytic performance for photocatalytic hydrogen production and the degradation of organic pollutants,as demonstrated by a hydrogen evolution rate of 523.7μmol g^(-1)h^(-1)and a ninefold higher RhB photodegradation rate compared to TiO_(2)MS.The work offers excellent flexibility for precisely constructing high-performance photocatalysts by understanding vacancy engineering.
基金supported by the National Key R&D Program of China (2019YFA0709200)the financial support from the National Natural Science Foundation of China (21874066, 81601632, and 31901010)+5 种基金the Natural Science Foundation of Jiangsu Province(BK20160616, China)the Fundamental Research Funds for Central Universitiesthe Priority Academic Program Development of Jiangsu Higher Education Institutions (Integration of Chinese and Western Medicine, China)the Key International Cooperation of the National Natural Science Foundation of China (No.81920108029)the Key Foundation for Social Development Project of the Jiangsu Province,China (BE2021741)Jiangsu Specially Appointed Professorship Foundation (China)
文摘Near-infrared(NIR)-light-triggered nanomedicine, including photodynamic therapy(PDT)and photothermal therapy(PTT), is growing an attractive approach for cancer therapy due to its high spatiotemporal controllability and minimal invasion, but the tumor eradication is limited by the intrinsic anti-stress response of tumor cells. Herein, we fabricate a tumor-microenvironment responsive CRISPR nanoplatform based on oxygen-deficient titania(TiO_(2-x)) for mild NIR-phototherapy. In tumor microenvironment, the overexpressed hyaluronidase(HAase) and glutathione(GSH) can readily destroy hyaluronic acid(HA) and disulfide bond and releases the Cas9/sgRNA from TiO_(2-x) to target the stress alleviating regulators, i.e., nuclear factor E2-related factor 2(NRF2) and heat shock protein 90a(HSP90a), thereby reducing the stress tolerance of tumor cells. Under subsequent NIR light illumination, the TiO_(2-x) demonstrates a higher anticancer effect both in vitro and in vivo. This strategy not only provides a promising modality to kills cancer cells in a minimal side-effects manner by interrupting anti-stress pathways but also proposes a general approach to achieve controllable gene editing in tumor region without unwanted genetic mutation in normal environments.
