简介:Afacilestep-by-stepapproachisdevelopedforsynthesizingthehigh-efficiencyandmagneticrecyclableFe_3O_4@SiO_2@Ag@Nitrepang-likenanocomposites.ThismethodinvolvescoatingFe_2O_3nanorodswithauniformsilicalayer,reductionin10%H_2/AratmospheretotransformtheFe_2O_3intomagneticFe_3O_4,andfinallydepositingAg@Nicore-shellnanoparticlesontheL-lysinemodifiedsurfaceofFe_3O_4@SiO_2nanorods.Thefabricatednanocompositesarefurthercharacterizedbyx-raydiffraction,transmissionelectronmicroscopy,scanningelectronmicroscope,Fouriertransforminfraredspectroscopy,andinductivelycoupledplasmamassspectroscopy.TheFe_3O_4@SiO_2@Ag@Nitrepang-likenanocompositesexhibitremarkablyhighercatalyticefficiencythanmonometallicFe_3O_4@SiO_2@AgnanocompositestowardthedegradationofRhodamineB(RhB)atroomtemperature,andmaintainsuperiorcatalyticactivityevenaftersixcycles.Inaddition,thesesamplescouldbeeasilyseparatedfromthecatalyticsystembyanexternalmagnetandreused,whichshowsgreatpotentialapplicationsintreatingwastewater.
简介:HydrotalciteprecursorsofLamodifiedNi-Al2O3andNi-SiO2catalystspreparedbyco-precipitationmethodandthecatalyticactivitieswereexaminedfortheproductionofCOx-freeH2byCH4decomposition.Physico-chemicalcharacteristicsoffresh,reducedandusedcatalystswereevaluatedbyXRD,TPRandO2pulsechemisorptions,TEMandBET-SAtechniques.XRDstudiesshowedphasesduetohydrotalcite-likeprecursorsinovendriedformproduceddispersedNiOspeciesuponcalcinationinstaticairabove450C.Ramanspectraofdeactivatedsamplesrevealedthepresenceofbothorderedanddisorderedformsofcarbon.Ni-La-Al2O3catalystwithamoleratioofNi:La:Al=2:0.1:0.9exhibitedtremendouslyhighlongevitywithahydrogenproductionrateof1300molH2mol1Ni.AdirectrelationshipbetweenNimetalsurfaceareaandhydrogenyieldswasestablished.
简介:High-performancethin-filmtransistors(TFTs)withalowthermalbudgetarehighlydesiredforflexibleelectronicapplications.Inthiswork,theTFTswithatomiclayerdepositedZnO-channel/Al_2O_3-dielectricarefabricatedunderthemaximumprocesstemperatureof200℃.First,weinvestigatetheeffectofpost-annealingenvironmentsuchasN_2,H_2-N_2(4%)andO_2onthedeviceperformance,revealingthatO_2annealingcangreatlyenhancethedeviceperformance.Further,wecomparetheinfluencesofannealingtemperatureandtimeonthedeviceperformance.Itisfoundthatlongannealingat200℃isequivalenttoandevenoutperformsshortannealingat300℃.ExcellentelectricalcharacteristicsoftheTFTsaredemonstratedafterO_2annealingat200℃for35min,includingalowoff-currentof2.3×10~(-13)A,asmallsub-thresholdswingof245mV/dec,alargeon/offcurrentratioof7.6×10~8,andahighelectroneffectivemobilityof22.1cm~2/V·s.Undernegativegatebiasstressat—10V,theabovedevicesshowbetterelectricalstabilitiesthanthosepost-annealedat300℃.Thusthefabricatedhigh-performanceZnOTFTwithalowthermalbudgetisverypromisingforflexibleelectronicapplications.
简介:PalladiumcatalystsaresupportedonTiO2,ZrO2,Al2O3,Zr0.5Al0.5O1.75andTiO2-Zr0.5Al0.5O1.75preparedbyco-precipitationmethod,respectively.CatalyticactivitiesformethaneandCOoxidationareevaluatedinagasmixturethatsimulatedtheexhaustfromlean-burnnaturalgasvehicles(NGVs).Pd/TiO2-Zr0.5Al0.5O1.75performsthebestcatalyticactivityamongthetestedfivecatalysts.ForCH4,thelight-offtemperature(T50)is254℃,andthecompleteconversiontemperature(T90)is280℃;forCO,T50is84℃,andT90was96℃.Varioustechniques,includingN2adsorption-desorption,X-raydiffraction(XRD),H2-temperature-programmedreduction(H2-TPR),X-rayphotoelectronspectroscopy(XPS),andscanningelectronmicroscopy(SEM)areemployedtocharacterizetheeffectofsupportsonthephysicochemicalpropertiesofpreparedcatalysts.N2adsorption-desorptionandSEMshowthatTiO2-Zr0.5Al0.5O1.75expressesuniformnano-particlesandlargemeso-porediametersof26nm.H2-TPRandXRDindicatethatPdOiswelldispersedonthesupportsandstronglyinteractedwitheachother.TheresultsofXPSshowthattheelectrondensityaroundPdOandtheproportionofactiveoxygenonTiO2-Zr0.5Al0.5O1.75aremaximaamongthefivesupports.
简介:用微波高温固相法合成了Er^3+单掺Lu2O3,Li^+与Er^3+共掺Lu2O3及Li^+,Zn^2+,Mg^2+掺杂Lu2O3∶Er^3+的荧光粉。实验表明金属离子Li^+、Zn^2+、Mg^2+、Er^3+掺杂Lu2O3,不影响Lu2O3的立方晶相。扫描电子显微镜测量表明,Li^+掺杂可以有效改善粉体的分散性和形貌,Li^+,Zn^2+,Mg^2+共掺杂获得的粉体颗粒分布更加均匀,粒径范围为80~100nm。379nm激发下,Li^+与Er^3+共掺样品发光较单掺Er^3+样品在565nm处的发光增强了4.5倍,而Li^+、Zn^2+、Mg^2+与Er^3+共掺样品较其发光增强5.3倍。980nm激发下,Li^+与Er^3+共掺样品,Li^+、Zn^2+、Mg^2+与Er^3+共掺样品的发光分别比单掺Er^3+样品在565nm处发光增强23倍与39倍,在662nm处发光强度分别增强20倍与43倍。379nm激发下,较单掺Er3+的样品,掺杂Li^+的样品和Li^+,Zn^2+,Mg^2+和Er^3+共掺的样品荧光寿命均有所增加,而Zn^2+、Er^3+共掺及Mg^2+、Er^3+共掺样品的荧光寿命则有所缩短。
简介:Ba1.0Co0.7Fe0.2Nb0.1O3-δ(BCFN)oxidewithperovskitecubicstructurewassynthesizedbysolidstatereactionmethod.CO2corrosionofBCFNmembranewasinvestigatedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),diffusereflectanceinfraredFouriertransformedspectroscopy(DRIFT)andX-rayabsorptionfinestructurespectroscopy(XAFS).Cobalt(Co)K-edgeabsorptionspectraofBCFNannealedinCO2revealthattheoxidationstatesofCoinallthesampleswerelargerthan+3andtheydecreasedwiththeincreaseofcalcinationtime.At800℃,1%CO2introducedintoHecouldspeedupthereductionofCocationsincomparisonwithpureHe.Inaddition,sulfateionsinthebulkofBCFNmembranepreferredtomigratetothesurfaceunderCO2calcinationandformmonoclinicBa(CO3)0.9(SO4)0.1besidesorthorhombicwitherite.Moreover,SEMresultsindicatethatthenucleationandgrowthofcarbonatesgrainsstartedatthegrainboundaryofthemembrane.
简介:Uptothisdate,researchersarestillfacingdifficultiestoexpandthetechnologyofdirectmethanolfuelcells(DMFCs)becauseofthehighoverpotentialrequiredtooxidizethemethanolanditsrelativelypoorperformanceduetoCOpoisoningoftheleading-highcostanodecatalyst.Inlinewiththis,wehavesuccessfullymodifiedthemorphologicalstructureandcompositionoflowcostcobaltbased-metaloxides,MCo2O4(M=ZnandNi),withthesimpleandnobleuseofpolyvinylpyrrolidone(PVP)asgrowthmodifierandsurfacestabilizerduringthesynthesisofnanoparticlesinourpreviousreports,whichshownhighelectrocatalyticactivityandstrongstability.DuetothegoodperformanceofourPVPmodifiedMCo2O4towardspseudocapacitorandoxygenevolutionreactionapplications,wedecidedtoextendourresearchstudytomethanoloxidationreaction.Remarkably,PVPmodifiedNiCo2O4electrodedirectlygrownonnickelfoamsubstrateviaasimplehydrothermalprocessexhibitedbetterperformancecomparedwithPVPmodifiedZnCo2O4andNiCo2O4withoutPVP.Ithadobtainedaremarkablylowonsetpotentialof0.285Vandhighcurrentdensityof280mAcm-2,andshowngreatstabilityandhighpoisontoleranceduringacontinuousCVcyclingandChronoamperometrytest,whichattainedhighefficiencyof86.86%and98.52%,respectively.ThesepositiveresultsofPVPmodifiedNiCo2O4electrodetowardsMORmightbeattributedtoitshierarchical3Dnanostructureswithhighlymesoporoussurfaceandlargesurfaceareawhichmayhaveprovidednumerouselectroactivesites,andtheexceptionalcorrosionstabilityofNiCo2O4electrodeinalkalinesolution.
简介:采用溶胶-凝胶法制备了Pt/Bi3.15Nd0.85Ti3O12/SrTiO3/Si多层电容即金属-铁电层-绝缘层-半导体结构,并对其电学性能进行了测试与分析。获得的存储窗口电压约为2.5V,漏电流密度低于10-8A·cm-2,保持时间达7.5h以上。制备的SrTiO3薄膜表现出较高的介电性和较好的绝缘性。
简介:测量了ZnO-TiO2-Bi2O3-CuO-Co2O3,ZnO-TiO2-Bi2O3-CuO-Cr2O3,ZnO-TiO2-Bi2O3-CuO-MnO2和ZnOTiO2-Bi2O3-CuO-MnO2-Co2O3-Cr2O3压敏陶瓷的正电子寿命谱及其电性能参数。研究了MnO2、Co2O3和Cr2O3掺杂对ZnO-TiO2-Bi2O3-CuO压敏陶瓷电子密度和电性能的影响。实验发现:ZnO-TiO2-Bi2O3-CuOCr2O3压敏陶瓷基体和晶界缺陷态的电子密度均最高,其压敏电压最低;ZnO-TiO2-Bi2O3-CuO-MnO2压敏陶瓷晶界缺陷态的电子密度最低,其压敏电压比前者高;ZnO-TiO2-Bi2O3-CuO-Co2O3压敏陶瓷基体(晶粒内)的电子密度最低,其压敏电压较高;而ZnO-TiO2-Bi2O3-CuO-MnO2-Co2O3-Cr2O3压敏陶瓷基体和晶界缺陷态的电子密度均较低,其压敏电压VT和非线性系数ɑ最高,漏电流IL最小。
简介:基于斯特林制冷式4×288元光伏型碲镉汞二维探测器,根据红外扫描成像系统原理,设计了一个扫描型长波红外连续变焦光学系统。根据系统指标要求对光学指标进行分解计算及光学优化设计得到系统的光学参数和外形结构图,并对扫描光学系统的冷反射进行分析优化。该光学系统采用三次成像的结构,由变焦望远镜组、扫描摆镜、中继镜组、成像镜组4部分组成,包含9片透镜和2片反射镜。为了降低校正色差成本,系统使用了硫系玻璃镜片。光学仿真结果表明:系统在耐奎斯特频率处的全视场光学传递函数大于0.35,全视场畸变小于2%。最后,对系统进行了成像实验验证,结果表明:该系统可以实现30.8-154mm范围内连续变焦,变焦过程中目标景物清晰,细节分辨率高,无冷反射现象出现,该系统具有分辨率高、热灵敏度高、像质清晰等特点。