Lithium–sulfur batteries exhibit unparalleled merits in theoretical energy density(2600 W h kg^(-1))among next-generation storage systems.However,the sluggish electrochemical kinetics of sulfur reduction reactions,su...Lithium–sulfur batteries exhibit unparalleled merits in theoretical energy density(2600 W h kg^(-1))among next-generation storage systems.However,the sluggish electrochemical kinetics of sulfur reduction reactions,sulfide oxidation reactions in the sulfur cathode,and the lithium dendrite growth resulted from uncontrollable lithium behaviors in lithium anode have inhibited high-rate conversions and uniform deposition to achieve high performances.Thanks to the“adsorption-catalysis”synergetic effects,the reaction kinetics of sulfur reduction reactions/sulfide oxidation reactions composed of the delithiation of Li_(2)S and the interconversions of sulfur species are propelled by lowering the delithiation/diffusion energy barriers,inhibiting polysulfide shuttling.Meanwhile,the anodic plating kinetic behaviors modulated by the catalysts tend to uniformize without dendrite growth.In this review,the various active catalysts in modulating lithium behaviors are summarized,especially for the defect-rich catalysts and single atomic catalysts.The working mechanisms of these highly active catalysts revealed from theoretical simulation to in situ/operando characterizations are also highlighted.Furthermore,the opportunities of future higher performance enhancement to realize practical applications of lithium–sulfur batteries are prospected,shedding light on the future practical development.展开更多
Spinel zinc ferrite(ZnFe_(2)O_(4),ZFO)is a potential photoanode material for photoelectrochemical(PEC)water splitting because of its ideal bandgap(1.9–2.1 eV)and superior chemical stability in aqueous solutions.Howev...Spinel zinc ferrite(ZnFe_(2)O_(4),ZFO)is a potential photoanode material for photoelectrochemical(PEC)water splitting because of its ideal bandgap(1.9–2.1 eV)and superior chemical stability in aqueous solutions.However,the low charge collection efficiency significantly hinders the improvement in PEC activity.Herein,we report an ultrafast and effective flame activation route to enhance the charge collection properties of ZFO.First,high-temperature flame(>1300℃)facilitated surface and grain boundary diffusions,increasing the grain size and connectivity of the ZFO nanoparticles.Second,the reducing atmosphere of the flame enabled the formation of surface defects(oxygen vacancy and Fe^(2+)),thereby increasing the charge carrier density and surface adsorption sites.Significantly,these two factors promoted charge transport and transfer kinetics,resulting in a 10-fold increase in the photocurrent density over the unactivated ZFO.Furthermore,we deposited a thin Al_(2)O_(3)overlayer to passivate the ZFO surface and then the NiFeOx oxygen evolution catalyst(OEC)to expedite hole injection into the electrolyte.This surface passivation and OEC deposition led to a remarkable photocurrent density of~1 mA/cm^(2)at 1.23 V versus the reversible hydrogen electrode,which is the highest value among all reported ZFO photoanodes.Notably,the NiFeOx/Al_(2)O_(3)/F-ZFO photoanode achieved excellent photocurrent stability over 55 h(96%retention)and superior faradaic efficiency(FE>94%).Our flame activation method is also effective in improving the photocurrent densities of other spinel ferrites:CuFe_(2)O_(4)(93 times),MgFe_(2)O_(4)(16 times),and NiFe_(2)O_(4)(12 times).展开更多
Developing low-cost and high-efficiency photocatalysts for hydrogen production from solar water splitting is intriguing but challenging. In this study, unique one-dimensional （1D） multi-node MoS2/CdS hetero-nanowir...Developing low-cost and high-efficiency photocatalysts for hydrogen production from solar water splitting is intriguing but challenging. In this study, unique one-dimensional （1D） multi-node MoS2/CdS hetero-nanowires （NWs） for efficient visible-light photocatalytic H2 evolution are synthesized via a facile hydrothermal method. Flower-like sheaths are assembled from numerous_ defect-rich O-incorporated {0001} MoS2 facet surrounded CdS NW stems are ultrathin nanosheets （NSs）, and {1120}- grown preferentially along the c-axis. Interestingly, the defects in the MoS2 NSs provide additional active S atoms on the exposed edge sites, and the incorporation of O reduces the energy barrier for H2 evolution and increases the electric conductivity of the MoS2 NSs. Moreover, the recombination of photoinduced charge carriers is significantly inhibited by the heterojunction formed between the MoS2 NSs and CdS NWs. Therefore, in the absence of noble metals as co-catalysts, the 1D MoS2 NS/CdS NW hybrids exhibit an excellent H2-generation rate of 10.85 mmol·g^-1·h^-1 and a quantum yield of 22.0% at ,λ = 475 nm, which is far better than those of Pt/CdS NWs, pure MoS2 NSs, and CdS NWs as well as their physical mixtures. Our results contribute to the rational construction of highly reactive nanostructures for various catalytic applications.展开更多
Facile design of economic-effective hydrogen evolution reaction(HER)catalysts with non-noble materials are promising for the production of renewable chemical fuels.Two-dimensional(2D)ultrathin transition metal dichalc...Facile design of economic-effective hydrogen evolution reaction(HER)catalysts with non-noble materials are promising for the production of renewable chemical fuels.Two-dimensional(2D)ultrathin transition metal dichalcogenides(TMDs)materials with large specific surface area and abundant catalytic active sites can significantly enhance their catalytic activities.Herein,we design and synthesize an atomically thin Ni-Se-S based hybrid nanosheet(NiSe1.2S0.8)via a simple solvothermal method,the thickness of NiSe1.2S0.8 nanosheets is only about 1.1 nm.Benefiting from the ultrathin nanostructure and rich defects,the optimal NiSe1.2S0.8 exhibits good electrocatalytic activity with the overpotential of 144 mV at−10 mA·cm−2,a small Tafel slope of 59 mV·dec−1,and outstanding catalytic stability in acid electrolyte for HER.The theoretical results show that hybrid electrocatalyst by S incorporation possesses the optimal adsorption free energy of hydrogen(ΔGH*).This study provides a simple method to synthesize a highperformance multicomponent electrocatalysts with the ultrathin nanostructures and abundant defects.展开更多
The development of high-efficiency electrocatalysts for oxygen evolution reactions （OERs） plays an important role in the water-splitting process. Herein, we report a facile way to obtain two-dimensional （2D） singl...The development of high-efficiency electrocatalysts for oxygen evolution reactions （OERs） plays an important role in the water-splitting process. Herein, we report a facile way to obtain two-dimensional （2D） single-unit-cell-thick layered double hydroxide （LDH） nanosheets （NSs, - 1.3 nm） within only 5 min. These nanosheets presented significantly enhanced OER performance compared to bulk LDH systems fabricated using the conventional co-precipitation method. The current strategy further allowed control over the chemical compositions and electrochemical activities of the LDH NSs. For example, CoFe-LDH NSs presented the lowest overpotential of 0.28 V at 10 mA/cm2, and the NiFe-LDHs NSs showed Tafel slopes of 33.4 mV/decade and nearly 100% faradaic efficiency, thus outperforming state-of-the-art IrO2 water electrolysis catalysts. Moreover, positron annihilation lifetime spectroscopy and high-resolution transmission electron microscopy observations confirmed that rich defects and distorted lattices occurred within the 2D LDH NSs, which could supply abundant electrochemically active OER sites. Periodic calculations based on density functional theory （DFT） further showed that the CoFe- and NiFe-LDHs presented very low energy gaps and obvious spin-polarization behavior, which facilitated high electron mobility during the OER process. Therefore, this work presents a combined experimental and theoretical study on 2D single-unit-cell-thick LDH NSs with high OER activities, which have potential application in water splitting for renewable energy.展开更多
Pulse microwave excite thermoacoustic(TA)shockwave to destroy tumor cells in situ.This has promising applications for precise tumor therapy in deep tissue.Nanoparticle(NP)with high microwave-acoustic conversion is the...Pulse microwave excite thermoacoustic(TA)shockwave to destroy tumor cells in situ.This has promising applications for precise tumor therapy in deep tissue.Nanoparticle(NP)with high microwave-acoustic conversion is the key to enhance the efficiency of therapy.In this study,we firstly developed defect-rich titanium nitride nanoparticles(TiN NPs)for pulse microwave excited thermoacoustic(MTA)therapy.Due to a large number of local structural defects and charge carriers,TiN NPs exhibit excellent electromagnetic absorption through the dual mechanisms of dielectric loss and resistive loss.With pulsed microwave irradiation,it efficiently converts the microwave energy into shockwave via thermocavitation effect,achieving localized mechanical damage of mitochondria in the tumor cell and yielding a precise antitumor effect.In addition to the therapeutic function,the NP-mediated TA process also generates images that provide valuable information,including tumor size,shape,and location for treatment planning and monitoring.The experimental results showed that the TiN NPs could be efficiently accumulated in the tumor via intravenous infusion.With the deep tissue penetration characteristics of microwave,the proposed TiN-mediated MTA therapy effectively and precisely cures tumors in deep tissue without any detectable side effects.The results indicated that defect-rich TiN NPs are promising candidates for tumor therapy.展开更多
Due to the limited electromagnetic wave(EMW)loss capacity and agglomeration,carbon black(CB)gradually fails to meet the increasingly harsh demanding conditions.Herein,defect-rich bamboo-like carbon nanotubes(CNTs)were...Due to the limited electromagnetic wave(EMW)loss capacity and agglomeration,carbon black(CB)gradually fails to meet the increasingly harsh demanding conditions.Herein,defect-rich bamboo-like carbon nanotubes(CNTs)were grown on CB by the process of chemical vapor deposition.CNTs prepared in situ on CB can assist it to build a developed multilevel conductive network and introduce plentiful CB/CNTs nano-interfaces.What’s more,the defects that accompany the growth of CNTs endow CNTs with a moderate conductivity and good impedance matching,thereby causing an effective microwave absorption(MA).Meanwhile,the high-density defects on CNTs can induce dipole polarization to further strengthen the EMW loss ability.The influence of CNTs with different growth time on MA performance has been explored.Profiting from the structural merits,the synthesized CB-CNT with CNTs growth time of 40 min exhibits the optimal absorbing property,which has the minimum reflection loss of-53.6 d B and maximum effective absorption bandwidth of 4.1 GHz with the thickness of 2.7 mm,covering almost the entire X band.The introduction of defect-rich CNTs significantly enhances the EMW loss ability of CB,which provides a rational strategy for the design of high-efficient microwave absorption materials.展开更多
目的:从临床指标方面系统评价富血小板纤维蛋白(PRF)与羟基磷灰石(HA)联用治疗牙周骨内缺损的疗效。方法:计算机检索PubMed、the Cochrane Library、Web of Science、维普、万方数据库、中国知网,检索关于PRF和HA联合治疗与PRF或HA单独...目的:从临床指标方面系统评价富血小板纤维蛋白(PRF)与羟基磷灰石(HA)联用治疗牙周骨内缺损的疗效。方法:计算机检索PubMed、the Cochrane Library、Web of Science、维普、万方数据库、中国知网,检索关于PRF和HA联合治疗与PRF或HA单独治疗牙周骨内缺损的随机对照实验(RCT),检索时限从建库至2023年6月。结果:最终纳入9个RCT,354个牙周骨内缺损位点。Meta分析显示,PRF与HA联合应用组与PRF组和HA组的探诊深度(PD)、临床附着丧失(CAL)、菌斑指数(PI)、牙龈指数(GI)的改变量差异均有统计学意义(P<0.05)。结论:目前的研究证据表明,PRP与HA联合应用治疗牙周骨内缺损均优于单用PRF或HA,由于纳入研究数量及质量的限制,还亟待更多高质量文献的证明。展开更多
Zn-air batteries with high energy density and safety have acquired enormous attention,while the practical application is hindered by the sluggish kinetics of the oxygen evolution reaction(OER)and the oxygen reduction ...Zn-air batteries with high energy density and safety have acquired enormous attention,while the practical application is hindered by the sluggish kinetics of the oxygen evolution reaction(OER)and the oxygen reduction reaction(ORR).In this work,a threedimensional(3D)defect-rich bifunctional electrocatalyst(CoFe/N CNFs)comprising irregular hollow CoFe nanospheres in Ndoped carbon nanofibers is presented,which is fabricated from CoFe ZIFs-derived(ZIF:zeolitic-imidazolate framework)polymer nanofibers precursor.The CoFe ZIFs with tunable particle size and composition are constructed using a confined synthesis strategy.Moreover,the Kirkendall diffusion process is available for forming the irregular hollow CoFe nanospheres,and the decomposition of polyvinylpyrrolidone(PVP)results in forming the defective carbon nanofibers,which provide more efficient active sites and enhance the electrocatalytic properties toward both OER and ORR.The optimized CoFe/N CNFs exhibit superior bifunctional activities,outperforming that of the benchmark Pt/C+RuO_(2) catalyst.As a result,the CoFe/N CNFs as an air-cathode endow the rechargeable Zn-air battery with an excellent power density of 149 mW·cm^(−2),energy density of 875 Wh·kg^(−1),and cycling stability.This work provides a new strategy to develop bifunctional electrocatalysts with desired nanostructure and regulated performance toward energy applications.展开更多
Photocatalytic water splitting for hydrogen(H_(2))production is a green sustainable technology,in which highly-efficient steady photocatalysts are fundamentally required.In this work,unique CdS/Cd_(0.5)Zn_(0.5)S-M0_(1...Photocatalytic water splitting for hydrogen(H_(2))production is a green sustainable technology,in which highly-efficient steady photocatalysts are fundamentally required.In this work,unique CdS/Cd_(0.5)Zn_(0.5)S-M0_(1-x)W_(x)S_(2) photocatalyst constructed by CdS hollow nano-spheres with successively surface-modified Cd_(0.5)Zn_(0.5)S shell and defect-rich MO_(1-x)W_(x)S_(2) ultrathin nanosheets was reported for the first time.Interestingly,the Cd_(0.5)Zn_(0.5)S shell could greatly enhance the photo-stability and reduce the carrier recombination of CdS.Meanwhile,enriching active sites and accelerating charge transfer could be achieved via anchoring defect-rich Mo_(1-x)W_(x)S_(2) onto CdS/Cd_(0.5)Zn_(0.5)S hollow heterostructures.Specifically,the optimized CdS/Cd_(0.5)Zn_(0.5)S-Mo_(1-x)W_(x)Sa(6 h Cd_(0.5)Zn_(0.5)S-coating,7 wt.%Mo_(1-x)W_(x)S_(2),x=0.5)hybrid delivered an exceptional H_(2) generation rate of 215.99 mmol·g^(-1)·h^(-1),which is approximately 502,134,and 23 times that of pure CdS,CdS/Cd_(0.5)Zn_(0.5)S,and 3 wt.%Pt-loaded CdS/Cd_(0.5)Zn_(0.5)S,respectively.Remarkably,a high H_(2) evolution reaction(HER)apparent quantum yield(AQY)of 64.81%was obtained under 420-nm irradiation.In addition,the CdS/Cd_(0.5)Zn_(0.5)S-Mo_(1-x)W_(x)S_(2) was also durable for H2 production under long-term irradiation.This work provides valuable inspirations to rational design and synthesis of efficient and stable hybrid photocatalysts for solar energy conversion.展开更多
基金fellowship funding supported by the Alexander von Humboldt Foundationfinancial funding support from the Natural Science Foundation of Jiangsu Province(BK.20210636)Natural Science Foundation of China(21773294 and 21972164)。
文摘Lithium–sulfur batteries exhibit unparalleled merits in theoretical energy density(2600 W h kg^(-1))among next-generation storage systems.However,the sluggish electrochemical kinetics of sulfur reduction reactions,sulfide oxidation reactions in the sulfur cathode,and the lithium dendrite growth resulted from uncontrollable lithium behaviors in lithium anode have inhibited high-rate conversions and uniform deposition to achieve high performances.Thanks to the“adsorption-catalysis”synergetic effects,the reaction kinetics of sulfur reduction reactions/sulfide oxidation reactions composed of the delithiation of Li_(2)S and the interconversions of sulfur species are propelled by lowering the delithiation/diffusion energy barriers,inhibiting polysulfide shuttling.Meanwhile,the anodic plating kinetic behaviors modulated by the catalysts tend to uniformize without dendrite growth.In this review,the various active catalysts in modulating lithium behaviors are summarized,especially for the defect-rich catalysts and single atomic catalysts.The working mechanisms of these highly active catalysts revealed from theoretical simulation to in situ/operando characterizations are also highlighted.Furthermore,the opportunities of future higher performance enhancement to realize practical applications of lithium–sulfur batteries are prospected,shedding light on the future practical development.
基金supported by the Basic Science Research Program of the National Research Foundation of Korea,funded by the Ministry of Science,ICT,and Future Planning(Grant Nos.NRF-2019R1A2C2002024 and 2021R1A4A1031357).
文摘Spinel zinc ferrite(ZnFe_(2)O_(4),ZFO)is a potential photoanode material for photoelectrochemical(PEC)water splitting because of its ideal bandgap(1.9–2.1 eV)and superior chemical stability in aqueous solutions.However,the low charge collection efficiency significantly hinders the improvement in PEC activity.Herein,we report an ultrafast and effective flame activation route to enhance the charge collection properties of ZFO.First,high-temperature flame(>1300℃)facilitated surface and grain boundary diffusions,increasing the grain size and connectivity of the ZFO nanoparticles.Second,the reducing atmosphere of the flame enabled the formation of surface defects(oxygen vacancy and Fe^(2+)),thereby increasing the charge carrier density and surface adsorption sites.Significantly,these two factors promoted charge transport and transfer kinetics,resulting in a 10-fold increase in the photocurrent density over the unactivated ZFO.Furthermore,we deposited a thin Al_(2)O_(3)overlayer to passivate the ZFO surface and then the NiFeOx oxygen evolution catalyst(OEC)to expedite hole injection into the electrolyte.This surface passivation and OEC deposition led to a remarkable photocurrent density of~1 mA/cm^(2)at 1.23 V versus the reversible hydrogen electrode,which is the highest value among all reported ZFO photoanodes.Notably,the NiFeOx/Al_(2)O_(3)/F-ZFO photoanode achieved excellent photocurrent stability over 55 h(96%retention)and superior faradaic efficiency(FE>94%).Our flame activation method is also effective in improving the photocurrent densities of other spinel ferrites:CuFe_(2)O_(4)(93 times),MgFe_(2)O_(4)(16 times),and NiFe_(2)O_(4)(12 times).
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Nos. 21431003 and 21521091） and China Ministry of Science and Technology （No. 2016YFA0202801）. We also thank Dr. Lina Zhang and Ms. Xiaohua Gu for their kind help with the TEM measurements.
文摘Developing low-cost and high-efficiency photocatalysts for hydrogen production from solar water splitting is intriguing but challenging. In this study, unique one-dimensional （1D） multi-node MoS2/CdS hetero-nanowires （NWs） for efficient visible-light photocatalytic H2 evolution are synthesized via a facile hydrothermal method. Flower-like sheaths are assembled from numerous_ defect-rich O-incorporated {0001} MoS2 facet surrounded CdS NW stems are ultrathin nanosheets （NSs）, and {1120}- grown preferentially along the c-axis. Interestingly, the defects in the MoS2 NSs provide additional active S atoms on the exposed edge sites, and the incorporation of O reduces the energy barrier for H2 evolution and increases the electric conductivity of the MoS2 NSs. Moreover, the recombination of photoinduced charge carriers is significantly inhibited by the heterojunction formed between the MoS2 NSs and CdS NWs. Therefore, in the absence of noble metals as co-catalysts, the 1D MoS2 NS/CdS NW hybrids exhibit an excellent H2-generation rate of 10.85 mmol·g^-1·h^-1 and a quantum yield of 22.0% at ,λ = 475 nm, which is far better than those of Pt/CdS NWs, pure MoS2 NSs, and CdS NWs as well as their physical mixtures. Our results contribute to the rational construction of highly reactive nanostructures for various catalytic applications.
基金This work was supported by the National Natural Science Foundation of China(Nos.21771191 and 21875285)Taishan Scholar Foundation(No.ts201511019)+1 种基金the Shandong Natural Science Fund(No.ZR2017QB012)the Fundamental Research Funds for the Central Universities(No.19CX05001A).
文摘Facile design of economic-effective hydrogen evolution reaction(HER)catalysts with non-noble materials are promising for the production of renewable chemical fuels.Two-dimensional(2D)ultrathin transition metal dichalcogenides(TMDs)materials with large specific surface area and abundant catalytic active sites can significantly enhance their catalytic activities.Herein,we design and synthesize an atomically thin Ni-Se-S based hybrid nanosheet(NiSe1.2S0.8)via a simple solvothermal method,the thickness of NiSe1.2S0.8 nanosheets is only about 1.1 nm.Benefiting from the ultrathin nanostructure and rich defects,the optimal NiSe1.2S0.8 exhibits good electrocatalytic activity with the overpotential of 144 mV at−10 mA·cm−2,a small Tafel slope of 59 mV·dec−1,and outstanding catalytic stability in acid electrolyte for HER.The theoretical results show that hybrid electrocatalyst by S incorporation possesses the optimal adsorption free energy of hydrogen(ΔGH*).This study provides a simple method to synthesize a highperformance multicomponent electrocatalysts with the ultrathin nanostructures and abundant defects.
基金This work was supported by the National Basic Research Program of China （No. 2014CB932103）, the National Natural Science Foundation of China （Nos. 21301016 and 21473013）, and the Beijing Municipal Natural Science Foundation （No. 2152016）.
文摘The development of high-efficiency electrocatalysts for oxygen evolution reactions （OERs） plays an important role in the water-splitting process. Herein, we report a facile way to obtain two-dimensional （2D） single-unit-cell-thick layered double hydroxide （LDH） nanosheets （NSs, - 1.3 nm） within only 5 min. These nanosheets presented significantly enhanced OER performance compared to bulk LDH systems fabricated using the conventional co-precipitation method. The current strategy further allowed control over the chemical compositions and electrochemical activities of the LDH NSs. For example, CoFe-LDH NSs presented the lowest overpotential of 0.28 V at 10 mA/cm2, and the NiFe-LDHs NSs showed Tafel slopes of 33.4 mV/decade and nearly 100% faradaic efficiency, thus outperforming state-of-the-art IrO2 water electrolysis catalysts. Moreover, positron annihilation lifetime spectroscopy and high-resolution transmission electron microscopy observations confirmed that rich defects and distorted lattices occurred within the 2D LDH NSs, which could supply abundant electrochemically active OER sites. Periodic calculations based on density functional theory （DFT） further showed that the CoFe- and NiFe-LDHs presented very low energy gaps and obvious spin-polarization behavior, which facilitated high electron mobility during the OER process. Therefore, this work presents a combined experimental and theoretical study on 2D single-unit-cell-thick LDH NSs with high OER activities, which have potential application in water splitting for renewable energy.
基金supported by the National Natural Science Foundation of China(No.62075066)the Science and Technology Planning Project of Guangdong Province,China(Nos.2019A1515012054)+1 种基金the Scientific and Technological Planning Project of Guangzhou City(No.201805010002)the Science and Technology Program of Guangzhou(No.2019050001).
文摘Pulse microwave excite thermoacoustic(TA)shockwave to destroy tumor cells in situ.This has promising applications for precise tumor therapy in deep tissue.Nanoparticle(NP)with high microwave-acoustic conversion is the key to enhance the efficiency of therapy.In this study,we firstly developed defect-rich titanium nitride nanoparticles(TiN NPs)for pulse microwave excited thermoacoustic(MTA)therapy.Due to a large number of local structural defects and charge carriers,TiN NPs exhibit excellent electromagnetic absorption through the dual mechanisms of dielectric loss and resistive loss.With pulsed microwave irradiation,it efficiently converts the microwave energy into shockwave via thermocavitation effect,achieving localized mechanical damage of mitochondria in the tumor cell and yielding a precise antitumor effect.In addition to the therapeutic function,the NP-mediated TA process also generates images that provide valuable information,including tumor size,shape,and location for treatment planning and monitoring.The experimental results showed that the TiN NPs could be efficiently accumulated in the tumor via intravenous infusion.With the deep tissue penetration characteristics of microwave,the proposed TiN-mediated MTA therapy effectively and precisely cures tumors in deep tissue without any detectable side effects.The results indicated that defect-rich TiN NPs are promising candidates for tumor therapy.
基金financially supported by National Natural Science Foundation of China(52072304,52172103)Natural Science Basic Research Plan in Shaanxi(2022JC-25)+1 种基金the Key R&D Program of Shaanxi Provence(2019ZDLGY04-02)China Postdoctoral Science Foundation(2021M702659)。
文摘Due to the limited electromagnetic wave(EMW)loss capacity and agglomeration,carbon black(CB)gradually fails to meet the increasingly harsh demanding conditions.Herein,defect-rich bamboo-like carbon nanotubes(CNTs)were grown on CB by the process of chemical vapor deposition.CNTs prepared in situ on CB can assist it to build a developed multilevel conductive network and introduce plentiful CB/CNTs nano-interfaces.What’s more,the defects that accompany the growth of CNTs endow CNTs with a moderate conductivity and good impedance matching,thereby causing an effective microwave absorption(MA).Meanwhile,the high-density defects on CNTs can induce dipole polarization to further strengthen the EMW loss ability.The influence of CNTs with different growth time on MA performance has been explored.Profiting from the structural merits,the synthesized CB-CNT with CNTs growth time of 40 min exhibits the optimal absorbing property,which has the minimum reflection loss of-53.6 d B and maximum effective absorption bandwidth of 4.1 GHz with the thickness of 2.7 mm,covering almost the entire X band.The introduction of defect-rich CNTs significantly enhances the EMW loss ability of CB,which provides a rational strategy for the design of high-efficient microwave absorption materials.
文摘目的:从临床指标方面系统评价富血小板纤维蛋白(PRF)与羟基磷灰石(HA)联用治疗牙周骨内缺损的疗效。方法:计算机检索PubMed、the Cochrane Library、Web of Science、维普、万方数据库、中国知网,检索关于PRF和HA联合治疗与PRF或HA单独治疗牙周骨内缺损的随机对照实验(RCT),检索时限从建库至2023年6月。结果:最终纳入9个RCT,354个牙周骨内缺损位点。Meta分析显示,PRF与HA联合应用组与PRF组和HA组的探诊深度(PD)、临床附着丧失(CAL)、菌斑指数(PI)、牙龈指数(GI)的改变量差异均有统计学意义(P<0.05)。结论:目前的研究证据表明,PRP与HA联合应用治疗牙周骨内缺损均优于单用PRF或HA,由于纳入研究数量及质量的限制,还亟待更多高质量文献的证明。
基金supported by the National Natural Science Foundation of China(Nos.11902256 and 51573148)the Natural Science Basic Research Program of Shaanxi(No.2019JQ-479)+2 种基金the Key Research and Development Program of Shaanxi Province(No.2020ZDGY01-01)the Fundamental Research Funds for the Central Universities(No.D5000220202)the China Scholarship Council and thanks eceshi(www.eceshi.com)for the Raman analysis.
文摘Zn-air batteries with high energy density and safety have acquired enormous attention,while the practical application is hindered by the sluggish kinetics of the oxygen evolution reaction(OER)and the oxygen reduction reaction(ORR).In this work,a threedimensional(3D)defect-rich bifunctional electrocatalyst(CoFe/N CNFs)comprising irregular hollow CoFe nanospheres in Ndoped carbon nanofibers is presented,which is fabricated from CoFe ZIFs-derived(ZIF:zeolitic-imidazolate framework)polymer nanofibers precursor.The CoFe ZIFs with tunable particle size and composition are constructed using a confined synthesis strategy.Moreover,the Kirkendall diffusion process is available for forming the irregular hollow CoFe nanospheres,and the decomposition of polyvinylpyrrolidone(PVP)results in forming the defective carbon nanofibers,which provide more efficient active sites and enhance the electrocatalytic properties toward both OER and ORR.The optimized CoFe/N CNFs exhibit superior bifunctional activities,outperforming that of the benchmark Pt/C+RuO_(2) catalyst.As a result,the CoFe/N CNFs as an air-cathode endow the rechargeable Zn-air battery with an excellent power density of 149 mW·cm^(−2),energy density of 875 Wh·kg^(−1),and cycling stability.This work provides a new strategy to develop bifunctional electrocatalysts with desired nanostructure and regulated performance toward energy applications.
基金support from the National Natural Science Foundation of China(Nos.51802170,51772162,and 21801150)the Natural Science Foundation of Shandong Province(Nos.ZR2019MB001,ZR2018BEM014,and ZR2019JQ14)+3 种基金the Youth Innovation and Technology Foundation of Shandong Higher Education Institutions,China(No.2019KJC004)the Taishan Scholar Project of Shandong Province(No.ts201712047)the Special Fund Project to Guide Development of Local Science and Technology by Central Government,the Open Research Fund of State Key Laboratory of Inorganic Synthesis and Preparative Chemistry of Jilin University(No.2019-22)the Taishan Scholar Program of Advantage and Characteristic Discipline Team of Eco-Chemical Process and Technology.
文摘Photocatalytic water splitting for hydrogen(H_(2))production is a green sustainable technology,in which highly-efficient steady photocatalysts are fundamentally required.In this work,unique CdS/Cd_(0.5)Zn_(0.5)S-M0_(1-x)W_(x)S_(2) photocatalyst constructed by CdS hollow nano-spheres with successively surface-modified Cd_(0.5)Zn_(0.5)S shell and defect-rich MO_(1-x)W_(x)S_(2) ultrathin nanosheets was reported for the first time.Interestingly,the Cd_(0.5)Zn_(0.5)S shell could greatly enhance the photo-stability and reduce the carrier recombination of CdS.Meanwhile,enriching active sites and accelerating charge transfer could be achieved via anchoring defect-rich Mo_(1-x)W_(x)S_(2) onto CdS/Cd_(0.5)Zn_(0.5)S hollow heterostructures.Specifically,the optimized CdS/Cd_(0.5)Zn_(0.5)S-Mo_(1-x)W_(x)Sa(6 h Cd_(0.5)Zn_(0.5)S-coating,7 wt.%Mo_(1-x)W_(x)S_(2),x=0.5)hybrid delivered an exceptional H_(2) generation rate of 215.99 mmol·g^(-1)·h^(-1),which is approximately 502,134,and 23 times that of pure CdS,CdS/Cd_(0.5)Zn_(0.5)S,and 3 wt.%Pt-loaded CdS/Cd_(0.5)Zn_(0.5)S,respectively.Remarkably,a high H_(2) evolution reaction(HER)apparent quantum yield(AQY)of 64.81%was obtained under 420-nm irradiation.In addition,the CdS/Cd_(0.5)Zn_(0.5)S-Mo_(1-x)W_(x)S_(2) was also durable for H2 production under long-term irradiation.This work provides valuable inspirations to rational design and synthesis of efficient and stable hybrid photocatalysts for solar energy conversion.
