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纳米LaMO3(M=Cr,Mn,Fe,Co)化合物的光催化氧化活性分析 总被引:16,自引:4,他引:16
采用柠檬酸络合法制备了纳米钙钛矿型LaMO3(M =Cr,Mn ,Fe ,Co)化合物 ,并对其进行XRD和TEM分析 ,发现所制样品具有单一晶相结构 ,粒径在 1~ 10 0nm之间。在纳米LaMO3(M =Cr,Mn ,Fe ,Co)悬浮体系中进行了水溶性染料酸性红 3B光催化降解实验 ,其光催化氧化活性变化趋势为LaCrO3相似文献
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利用Co(Ⅱ)、Co(Ⅲ)与乙酰丙酮生成的螯合物的不同水溶性,通过萃取将Co(Ⅱ)、Co(Ⅲ)进行分离,应用X射线荧光光谱仪(XRF)测定对二甲苯(PX)液相氧化反应中的Co(Ⅱ)和Co(Ⅲ)含量.结果表明:XRF的操作电流为20μA,测试时间为100 s时,测定PX中的Co(Ⅱ)和Co(Ⅲ)含量,其加标回收率为92%... 相似文献
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《Journal of the European Ceramic Society》2003,23(14):2473-2478
Ba(Co1/3Nb2/3)O3(BCN) has a 1:2 ordered hexagonal structure. A large amount of the liquid phase, which contains high concentrations of Ba and Nb ions was found in the BCN ceramics. Q-values of BCN increased with increasing sintering temperature; however, it significantly decreased when the sintering temperature exceeded 1400 °C. The presence of a large amount of liquid phase could be responsible for the decrease of the Q-value. For (1−x)Ba(Co1/3Nb2/3)O3–xBa(Zn1/3Nb2/3)O3 [(1−x)BCN–xBZN] ceramics, the 1:2 ordered hexagonal structure was observed in the specimens with x⩽0.3 and the BaNb6O16 second phase was found in the specimens with x⩾0.6. Grain growth, which is related to the BaNb6O16 second phase occurred in the specimens with x⩾0.5. In this work, the excellent microwave dielectric properties of τf=0.0 ppm/°C, εr=34.5 and Q×f=97,000 GHz were obtained for the 0.7BCN–0.3BZN ceramics sintered at 1400 °C for 20 h. 相似文献
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《Journal of the European Ceramic Society》2014,34(3):703-715
The thermal and chemical expansion of Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) and SrCo0.8Fe0.2O3−δ (SCF) mixed ionic-electronic conductors were studied in combination with oxygen nonstoichiometry (δ) at 298–1223 K and p(O2) = 10−4 to 1.00 atm. In order to minimize the effects of phase separation or oxygen-vacancy ordering processes, the data were collected in dynamic cooling mode using dense ceramic samples. The procedure was justified by a very fast equilibration at given p(O2) in high-temperature range demonstrated for ceramics samples with different specific surface area. The difference in nonstoichiometry of BSCF and SCF at temperatures ≥973 K was found to be ≤0.03 oxygen atoms per formula unit. BSCF demonstrates favorably smaller chemical expansion compared to SCF and many other mixed conductors, originating from smaller δ variations and larger unit cell less sensitive to temperature and nonstoichiometry changes. Excessive thermochemical expansion impedes however the use of BSCF in single-phase fuel cell cathodes and planar mixed-conducting membranes. 相似文献
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通过TG、DSC等热分析技术可以得到物质在常规热分解过程的主要固相产物.为了进一步考察[Co(CHZ)3](ClO4)2(CoCP)的热分解行为,采用T-jump/FT-IR在线分析技术测定了CoCP的快速热分解气体产物.CoCP在1 atm下以一定的升温速率达到设定的温度进行快速热分解.利用其快速热分解过程的控制电压变化曲线,可以得知CoCP在快速热分解过程的吸热、放热变化情况;用快速扫描傅立叶变换红外,可以解析分解过程中逸出的12种红外活性气体.研究发现,在CoCP快速热分解过程所产生的12种气相产物中,以CO的浓度最高,NO和HCN为主要的含氮气相产物,含碳气相产物以CO,CO2和H2C=O为主;并给出了其主要气相产物的浓度随时间的变化曲线. 相似文献
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《化工进展》2017,(Z1)
钙钛矿型氧化物催化剂(ABO3)具有廉价易得、高热稳定性、催化活性高的优点,在催化一氧化碳(CO)低温脱除领域具有重要的理论研究意义和实际应用价值。本研究中,以聚苯乙烯(PS)微球、碳微球为模板,硝酸镧、硝酸钴、硝酸铁为金属源,柠檬酸为络合剂,通过溶胶-凝胶法制备了多孔LaCoO_3和多孔LaFeO_3催化剂。采用X射线衍射、热重-差热、扫描电镜、透射电镜和氮气吸附-脱附等手段对所得样品进行了系统表征分析。结果表明:所制备的催化剂具有高纯度和高热稳定性。加入11.12g PS微球所制备的多孔LaCoO_3催化剂平均颗粒粒径为13nm,加入0.5g碳微球制备的多孔LaFeO_3催化剂平均粒径为19nm,且具有介孔和微孔分级孔结构。催化性能测试结果表明:在同等条件下对CO转化率达到50%时,多孔LaCoO_3和多孔LaFeO_3使得催化温度分别降低了43℃和32℃;CO完全转化温度则分别降低了90℃和60℃。 相似文献
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近年来锂离子电池对能量密度的要求越来越高,同时也希望有较低的成本和良好的性能。采用532型Li(Ni,Co,Mn)O2三元材料设计成2200 mAh的电池,并对电池的电性能与安全性能进行了相关的测试。结果表明,采用该材料制作的电池克容量发挥可达160 mAh/g,具有较好的循环性能、倍率性能与安全性能。 相似文献
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用Co(NH3)2+6的氨水溶液可同时实现NO的氧化和吸收过程.NO 与Co(NH3)2+6气液反应动力学研究表明,NO与Co(NH3)2+6的反应为瞬间反应,当Co(NH3)2+6浓度低于20mmol8226;L-1时过程为双膜控制,当Co(NH3)2+6浓度大于20mmol8226;L-1时过程逐渐变为气膜控制.NO的吸收速度随温度的升高而降低,气相中氧的存在有利于NO的吸收,但当氧的含量高于5.2%后再继续增加氧的含量NO吸收速率提高不大.经研究建立了有氧时NO 与Co(NH3)2+6气液反应动力学方程. 相似文献
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用Co(NH3)2+6的氨水溶液可同时实现NO的氧化和吸收过程.NO 与Co(NH3)2+6气液反应动力学研究表明,NO与Co(NH3)2+6的反应为瞬间反应,当Co(NH3)2+6浓度低于20mmol8226;L-1时过程为双膜控制,当Co(NH3)2+6浓度大于20mmol8226;L-1时过程逐渐变为气膜控制.NO的吸收速度随温度的升高而降低,气相中氧的存在有利于NO的吸收,但当氧的含量高于5.2%后再继续增加氧的含量NO吸收速率提高不大.经研究建立了有氧时NO 与Co(NH3)2+6气液反应动力学方程. 相似文献
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激光作为一种瞬时高能的加工工艺,近年来逐渐实现多元化的应用,能够大幅缩短材料的制备时长,降低时间成本。基于溶胶凝胶法,通过激光加热辅助制备(La0.7Sr0.3)0.93(Ti0.93Co0.07)O3钙钛矿粉体,该工艺可使粉体制备时长由十几小时缩短至几十秒,且组织性能表现优异。通过X射线衍射(XRD)和扫描电镜(SEM)表征发现,激光加热后粉体的衍射峰锐化且无其他杂质峰生成,粉体表面致密,呈阶梯状。电化学测试结果表明:激光加热后CV曲线面积增大,起始电位为0.430 V,当电位为0.8 V时电流密度达到200.1 mA/cm2,是高温煅烧后粉体电流密度的2.2倍,内阻为0.941 17Ω·cm2,有着良好的氧化还原性能及OER催化活性。激光加热能够代替高温煅烧作为一种稳定钙钛矿晶型结构的高效制备工艺。 相似文献
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《Ceramics International》2017,43(6):5032-5040
Nanostructured La-based perovskite oxides − LaMO3 (M=Al, Co, Fe) were synthesized by a new co-precipitation procedure using metal nitrate and carbonate salts as starting materials. X-ray diffraction and energy dispersive X-ray spectroscopic results confirmed the formation of single-phase nanocrystalline perovskite oxides with high purity. Characterizations by scanning/transmission electron microscopy and nitrogen adsorption revealed that LaAlO3 was produced in the form of rectangular porous nanorods exhibiting much larger surface area and porosity compared with densely aggregated LaCoO3 particles and loosely clustered LaFeO3 nanoparticles with cracked-egg morphologies. The materials were characterized for gas sensing towards ethanol at 200–350 °C. From gas-sensing results, the LaAlO3 sensor displayed n-type gas-sensing behaviors with considerably higher ethanol response than p-type LaFeO3 and LaCoO3 sensors, respectively. In particular, the LaAlO3 sensor exhibited a high response of 16.45–1000 ppm ethanol and excellent ethanol selectivity against NO2, SO2, CO and H2 at 350 °C. The superior gas-sensing performances could be attributed to the effective receptor function, transducer function and utility factor of LaAlO3 nanorod structures prepared by the co-precipitation method. 相似文献
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将富锂锰基正极材料Li2MnO3·LiMO2(M=Co,Ni)分为LiMO2和Li2MnO3两部分,基于密度泛函理论第一性原理方法对其分别进行了研究,分析和计算了LiMO2(M=Co,Ni)的结构和性能及Li2MnO3的脱锂过程。结果表明:在LiMO2(M=Co,Ni)和Li2MnO3中锂以离子形式存在,LiNiO2体系的导电性优于LiCoO2体系,Li2MnO3在脱锂过程中锂离子首先从锂层中脱出,之后从过渡金属层进一步脱锂,其中锂脱出造成的电荷变化主要由O的氧化来补偿。 相似文献
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《Ceramics International》2020,46(9):13047-13053
Porous (Ba,Sr)(Co,Fe)O3-δ (BSCF) ceramics with high open porosity and good electrical conductivity was fabricated using Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), which shows a high mixed ionic-electronic conductivity. In general, during the fabrication of porous ceramics by the sacrificial template method using pore former particles, closed pores are easily formed unless sufficient pore former particles are added. In this study, we have devised a method using the gelatinization-retrogradation phenomena of starch for producing a porous body with an excellent percolated pore network structure. By dispersing BSCF and starch in an aqueous slurry (0–50% by weight) and heating, gelatinization of the starch occurred and the starch particles adhered to each other. Furthermore, in order to retain the percolated structure, the water solvent was removed by freeze-drying without heating to obtain a dried green body. The sintering behavior of the porous BSCF bodies prepared under various conditions was characterized by microstructural observations and relative density measurements. By optimizing the process conditions of the gelatinization and retrogradation, a porous body having an open porosity of 48.3%, and with 99% of the total pores open, was obtained. The matrix was also well connected and showed a sufficiently high conductivity which was similar to the porous bodies made by the traditional sacrificial template method. 相似文献
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通过简便的一步水热法成功制备出了Co(CO_3)_(0. 35)Cl_(0. 20)(OH)_(1.10)(Cobalt chloride carbonate hydroxide,CCCH)纳米线,并采用XRD、SEM等表征了CCCH的结构和形貌,其平均直径约为200 nm,长度大约为5μm。测定了CCCH纳米线电极的超级电容器性能,在1 A/g时,其比容量达到1536 F/g,即使在32 A/g的高电流密度下,比电容也能达到741 F/g。结果表明制得的CCCH纳米线具有良好的电化学性能,是一种有潜力的超级电容器电极材料。 相似文献
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NO与Co(NH_3)_6~(2+)气液反应动力学 总被引:2,自引:0,他引:2
用Co(NH3 ) 2 + 6的氨水溶液可同时实现NO的氧化和吸收过程 .NO与Co(NH3 ) 2 + 6气液反应动力学研究表明 ,NO与Co(NH3 ) 2 + 6的反应为瞬间反应 ,当Co(NH3 ) 2 + 6浓度低于 2 0mmol·L-1时过程为双膜控制 ,当Co(NH3 ) 2 + 6浓度大于 2 0mmol·L-1时过程逐渐变为气膜控制 .NO的吸收速度随温度的升高而降低 ,气相中氧的存在有利于NO的吸收 ,但当氧的含量高于 5 2 %后再继续增加氧的含量NO吸收速率提高不大 .经研究建立了有氧时NO与Co(NH3 ) 2 + 6气液反应动力学方程 相似文献