Ultraviolet （UV） photodetector constructed by ZnO material has attracted intense research and commercial interest. However, its photoresistivity and photoresonse are still unsatisfied. Herein, we report a novel meth...Ultraviolet （UV） photodetector constructed by ZnO material has attracted intense research and commercial interest. However, its photoresistivity and photoresonse are still unsatisfied. Herein, we report a novel method to assemble ZnO nanoparticles （NPs） onto the reduced graphite oxide （RGO） sheet by simple hydrothermal process without any surfactant. It is found that the high-quality crystallized ZnO NPs with the average diameter of 5 nm are well dispersed on the RGO surface, and the density of ZnO NPs can be readily controlled by the concentration of the precursor. The photodetector fabricated with this ZnO NPs- RGO hybrid structure demonstrates an excellent photoresponse for the UV irradiation. The results make this hybrid especially suitable as a novel material for the design and fabrication of high performance UV photodector.展开更多
Cast Al alloys are widely employed for engine components,structural parts,gear box,chassis,etc.and subjected to mechanical cyclic load during operation.The accurate fatigue life prediction of these alloys is essential...Cast Al alloys are widely employed for engine components,structural parts,gear box,chassis,etc.and subjected to mechanical cyclic load during operation.The accurate fatigue life prediction of these alloys is essential for normal operation as fatigue cracks initiated during operation induce the lubrication oil leak and serious safety hazard.Microstructural heterogeneity,including shrinkage/gaspores and secondary phase particles,is the most detrimental factor that affects fatigue life of cast Al alloys.The approximate fatigue life cycles could be estimated based on the size distribution and locations of shrinkage pores/defects.The relationship between crack population and stress was reported by statistical distributions and the cumulative probability for cast Al alloys fail at a certain stress could be predicted by combination of Paris law and pore size distribution.Pore depth was found to dominate the stress field around the pore on the surface and the maximum stress increases sharply when the pore intercepted with the surface at its top.The microstructure of cast Al alloys usually is composed of primary Al dendrites,eutectic silicon,Fe-rich particles and other intermetallic particles are dependent upon alloy composition and heat treatment.The coalescence of microcracks initiated from the fractured secondary phases was clearly found and can accelerate the initiation and propagation of the fatigue cracks.A link between defect features and the fatigue strength needs to be established through a good understanding of the fatigue damage mechanisms associated with the microstructural features under specific loading conditions.This paper reviews the influences of shrinkage/gaspores and secondary phase particles,formed during casting process,on the fatigue life of Al-Si-Mg cast Al alloys.展开更多
Ag2O has attracted much recent attention,because of its high photocatalytic activity in the ultraviolet(UV)‐visible region.However,there have been few reports on the near‐infrared(NIR)photocatalytic activity of Ag2O...Ag2O has attracted much recent attention,because of its high photocatalytic activity in the ultraviolet(UV)‐visible region.However,there have been few reports on the near‐infrared(NIR)photocatalytic activity of Ag2O.This paper reports the high NIR photocatalytic activity of Ag2O nanoparticles.Ag2O is unsuitable for application in full‐solar‐spectrum photocatalysis,because it is unstable under UV irradiation.A surface sulfurization process was carried out to address this issue.Specifically,a layer of Ag2S2O7nanoparticles was grown on the surface of the Ag2O nanoparticles,to improve the stability of the Ag2O photocatalyst and enhance its photocatalytic activity in the UV,visible and NIR regions.The Ag2O/Ag2S2O7heterostructure is a stable and efficient full‐solar‐spectrum photocatalyst.It has potential application in the photodegradation of organic pollutants,and more generally in environmental engineering where full utilization of the solar spectrum is required.展开更多
基金This work is supported by MOST of China （No.2011CB921403）, the Chinese Academy of Science, and the National Natural Science Foundation of China （No.10874165, No.90921013, No.11074231, and No. 11004179）.
文摘Ultraviolet （UV） photodetector constructed by ZnO material has attracted intense research and commercial interest. However, its photoresistivity and photoresonse are still unsatisfied. Herein, we report a novel method to assemble ZnO nanoparticles （NPs） onto the reduced graphite oxide （RGO） sheet by simple hydrothermal process without any surfactant. It is found that the high-quality crystallized ZnO NPs with the average diameter of 5 nm are well dispersed on the RGO surface, and the density of ZnO NPs can be readily controlled by the concentration of the precursor. The photodetector fabricated with this ZnO NPs- RGO hybrid structure demonstrates an excellent photoresponse for the UV irradiation. The results make this hybrid especially suitable as a novel material for the design and fabrication of high performance UV photodector.
基金Projects(11790282,U1534204,11572267,51804202,51705344)supported by the National Natural Science Foundation of ChinaProject(E2019210292)supported by the Natural Science Foundation of Hebei Province,China+6 种基金Project(A2019210204)supported by the National Natural Science Foundation for Distinguished Young Scholars,ChinaProject(KQTD20170810160424889)supported by the Shenzhen Peacock Team Program,ChinaProject(2019DB013)supported by the Key Research Project of Southern Xinjiang,ChinaProject(C201821)supported by the High Level Talent Support Project in Hebei,ChinaProject supported by the Youth Top-notch Talents Supporting Plan of Hebei Province,ChinaProject(MCMS-E-0519G04)supported by the State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics,ChinaProject(201919)supported by the Open Fund of State Key Laboratory of Metastable Materials Science and Technology,Yanshan University,China。
文摘Cast Al alloys are widely employed for engine components,structural parts,gear box,chassis,etc.and subjected to mechanical cyclic load during operation.The accurate fatigue life prediction of these alloys is essential for normal operation as fatigue cracks initiated during operation induce the lubrication oil leak and serious safety hazard.Microstructural heterogeneity,including shrinkage/gaspores and secondary phase particles,is the most detrimental factor that affects fatigue life of cast Al alloys.The approximate fatigue life cycles could be estimated based on the size distribution and locations of shrinkage pores/defects.The relationship between crack population and stress was reported by statistical distributions and the cumulative probability for cast Al alloys fail at a certain stress could be predicted by combination of Paris law and pore size distribution.Pore depth was found to dominate the stress field around the pore on the surface and the maximum stress increases sharply when the pore intercepted with the surface at its top.The microstructure of cast Al alloys usually is composed of primary Al dendrites,eutectic silicon,Fe-rich particles and other intermetallic particles are dependent upon alloy composition and heat treatment.The coalescence of microcracks initiated from the fractured secondary phases was clearly found and can accelerate the initiation and propagation of the fatigue cracks.A link between defect features and the fatigue strength needs to be established through a good understanding of the fatigue damage mechanisms associated with the microstructural features under specific loading conditions.This paper reviews the influences of shrinkage/gaspores and secondary phase particles,formed during casting process,on the fatigue life of Al-Si-Mg cast Al alloys.
基金supported by the National Natural Science Foundation of China(51372142)the Innovation Research Group(51321091)the Program of Introducing Talents of Discipline to Universities in China(111 program,b06015)~~
文摘Ag2O has attracted much recent attention,because of its high photocatalytic activity in the ultraviolet(UV)‐visible region.However,there have been few reports on the near‐infrared(NIR)photocatalytic activity of Ag2O.This paper reports the high NIR photocatalytic activity of Ag2O nanoparticles.Ag2O is unsuitable for application in full‐solar‐spectrum photocatalysis,because it is unstable under UV irradiation.A surface sulfurization process was carried out to address this issue.Specifically,a layer of Ag2S2O7nanoparticles was grown on the surface of the Ag2O nanoparticles,to improve the stability of the Ag2O photocatalyst and enhance its photocatalytic activity in the UV,visible and NIR regions.The Ag2O/Ag2S2O7heterostructure is a stable and efficient full‐solar‐spectrum photocatalyst.It has potential application in the photodegradation of organic pollutants,and more generally in environmental engineering where full utilization of the solar spectrum is required.
