La0.6Sr0.4Fe0.8Co0.2O3的甘氨酸-硝酸盐法合成与表征

采用甘氨酸-硝酸盐法(GNP)制备La0.6Sr0.4Fe0.8Co0.2O3初级粉料, 研究甘氨酸用量对初级产物和热处理产物的晶体结构和显微形貌的影响, 并用直流四探针法测量烧结体的电导率.在286.8～365.7 ℃范围内, 初级粉料中残余有机物和残碳氧化分解.钙钛矿结构La0.6Sr0.4Fe0.8Co0.2O3在720.9 ℃左右形成.经750 ℃(保温1 h)热处理即可制得单相钙钛矿结构La0.6Sr0.4Fe0.8Co0.2O3.甘氨酸-硝酸盐法所制粉体颗粒细小, 有轻微烧结现象, 这是由燃烧温度高导致的, 经短时间研磨后团聚状况可得到改善.与固相合成法相比, GNP法所制样品的电导率较高.     

钴钨复合电极在碱性介质中的电催化析氢性能

为提高电极的电催化析氢性能,在钴电沉积中加入钨粉,制得钴钨复合电极,采用阴极极化曲线法、交流阻抗技术和扫描电子显微技术研究了电极在碱性介质中的催化析氢性能。与钴电极相比,钴钨复合电极表面粗糙,具有较大的交换电流密度和较小的析氢反应电阻。结果表明：复合电极的电催化析氢性能优于钴电极。     

铅电极上电聚合聚苯胺及其析氧电催化性能研究

在苯胺-硫酸电解液中,采用电化学阳极氧化法在纯铅表面电沉积制备聚苯胺(PAn)膜层。探讨了苯胺电聚合过程的影响因素及其规律,并考察了所得Pb/PAn膜电极材料的析氧电催化特性。结果表明,在一定的恒电流密度下,聚苯胺的沉积量与时间成正比;与空白Pb电极相比,Pb/PAn膜电极的析氧电位负移0.13~0.36V,交换电流密度提高2~4个数量级,显示出良好的析氧电催化特性。作为析氧阳极,Pb/PAn膜电极在有色金属电解提取等方面具有潜在应用价值。     

钛基涂层氧化物析氧阳极材料的研究进展

介绍了钛基涂层氧化物析氧阳极(DSA)的制备方法,包括热分解、磁控溅射、溶胶–凝胶和电沉积等方法。分析了DSA阳极的析氧原理。指出了DSA电极存在的问题及未来的发展趋势。     

Pt-WC/Ti电极在酸性介质中的电催化析氢性能

通过复合电沉积技术制备出Ｐｔ－ＷＣ／Ｔｉ电极,并研究了Ｐｔ－ＷＣ／Ｔｉ电极在酸性介质中的电催化析氢性能,实验结果表明：复合电极的电催化析氢性能高于镀铂电极,性能的提高完全归因于电极比表面积的增加,该复合电极代替铂电极的使用具有一定的意义。     

Ni-Fe-V LDHs@NiS2/C复合材料的制备及其电催化析氧性能研究

为提供具有成本竞争力的可再生清洁能源-氢能,开发有效的非贵金属析氧催化剂受到了广泛的关注。本文利用二步溶剂热法制备了Ni-Fe-V LDHs@NiS_2/C的复合催化材料,对产物进行了XRD、SEM、I/E、EIS等表征;同时对比研究了不同总金属离子浓度下硫化处理对电催化析氧性能的影响。结果表明,当总金属离子浓度为30mmol·L~(-1)时所制得的Ni-Fe-V LDH/C材料,在1mol·L~(-1)KOH电解质中,电流密度为10m A·cm~(-2)时,析氧超电势为513m V,而所得的Ni-Fe-V LDHs@NiS_2/C的复合催化材料的析氧超电势仅为352mV,其析氧超电势降低了161mV。这为降低电催化析氧过电势提供了一种新的策略。     

电沉积Ni-P-ZrO2复合电极析氢电催化性能的研究

用电沉积方法制备了镍－磷－二氧化锆复合电极。通过阴极极化曲线,交流阻抗等电化学技术研究其析氢催化性能,并用扫描电镜观察电极的表面形貌。实验结果表明,在80℃,25％氢氧化钠碱性溶液中镍－磷－二氧化锆的表观交换电流密度及表面粗糙度皆大于镍,镍－磷电极,而反应电阻较小。说明镍－磷中引入二氧化锆所形成的复合镀层具有较高的析氢催化活性和良好的电化学稳定性。     

浸渍Gd0.2Ce0.8O1.9对固体氧化物燃料电池La0.8Sr0.2Co0.2Fe0.8O3-δ阴极铬中毒影响的研究

固体氧化物燃料电池连接体中存在铬元素,会对阴极材料产生毒化作用,严重影响了阴极的电化学性能.采用浸渍法制备了用于固体氧化物燃料电池的La0.8Sr0.2Co0.2Fe0.8O3-δ(LSCF)-Gd0.2Ce0.8O1.9(GDC)复合阴极,以电化学测试为基础,结合扫描电子显微镜、电感耦合等离子光谱、X射线光电子能谱等...     

Pb—WC复合电极的电催化机理的研究

本文对 H_2在 Pb-WC 复合电催化电极上的析出机理建立了数学模型,验证了反应机理。用一种新的定量的计算法研究了反应控制步骤的活化能,得出 Pb 复合 WC 后使得氢析出催化活性提高的主要原因是反应控制步骤活化能降低了的结论。     

大孔SiO_2载体制备La_(0.8)Sr_(0.2)CoO_3及其对NO+CO的催化性能

以具有高比表面积的大孔SiO_2为载体,采用浸渍法,通过控制浸渍液浓度的不同原位制备不同负载率的稀土钙钛矿型复合氧化物La_(0.8)Sr_(0.2)CoO_3/SiO_2样品。利用X射线衍射、比表面积、扫描电镜和X射线光电子能谱等分析方法对样品进行表征,结果表明,载体表面均匀负载La_(0.8)Sr_(0.2)CoO_3,且随着负载率增加,样品比表面积下降。考察不同负载率的La_(0.8)Sr_(0.2)CoO_3/SiO_2样品对NO+CO的催化活性,结果表明,与比表面积和结晶度相比,负载率在该催化实验体系中是影响最大的因素,综合催化效果最好的样品负载La_(0.8)Sr_(0.2)CoO_3质量分数为50.47%。     

溶胶-凝胶法制备La_(0.8)Sr_(0.2)MnO_3涂层的研究

采用溶胶-凝胶法在氧化铝基体制备La0.8Sr0.2MnO3涂层。通过热重分析、差示扫描量热分析、X射线衍射分析、扫描电镜等手段对涂层制备工艺、相组成以及表面形貌进行了分析。结果表明,用溶胶-凝胶法可制备La0.8Sr0.2MnO3单相涂层;涂层表面致密性好,但有裂纹,且不平整;涂层均匀且与基体间界面不明锐,涂层厚度约为0.5μm;另外,随Sr含量增加,La1-xSrxMnO3涂层方块电阻减小,当x=0.3时达到最小值。     

Sm0.5Sr0.5CoO3–Sm0.2Ce0.8O1.9 Composite Oxygen Electrodes for Solid Oxide Electrolysis Cells

In this paper, a series of Sm_0.5Sr_0.5CoO₃–Sm_0.2Ce_0.8O_1.9 (SSC–SDC) composite with different ratios were prepared and characterized as oxygen electrodes for solid oxide electrolysis cells (SOECs). Yttria‐stabilized zirconia (YSZ) was selected as the electrolyte with a SDC barrier layer to avoid detrimental solid state interaction between SSC and YSZ. At 850 °C, the impedance spectra showed that the optimum SDC content in the composite electrode was found to be about 30 wt.%, which showed a much lower area specific resistance of 0.03 Ω cm². The electrochemical performances of a Ni–YSZ hydrogen electrode supported YSZ membrane SOEC with the SSC–SDC73 oxygen electrode were also measured at 750–850 °C. The hydrogen production rate calculated from the Faraday's law was 327 mL cm^–2 h^–1 at 850 °C at an electrolysis voltage of 1.3 V with a steam concentration of ∼40%, which indicated that the SSC–SDC73 was a promising oxygen electrode candidate for high temperature electrolysis cells.     

La0.8Sr0.2MnO3 MgAl2O4丝网蜂窝催化剂用于低浓度甲烷催化燃烧

首先,采用沉积-沉淀法制备了与镁铝尖晶石(Mg Al2O4,简称MA)载体复合的镧锶锰钙钛矿(La_(0.8)Sr_(0.2)MnO_3,简称LSM)催化剂LSMn,考察了MA与LSM的物质的量比(n)、前驱体老化和焙烧温度系列制备条件的影响,在程序升温微反应器中测试了LSMn粉体对低浓度甲烷催化燃烧反应的活性,并用FTIR、H2-TPR、BET、XRD和SEM手段对催化剂进行表征。结果表明:在10℃老化和800℃下焙烧的LSM4性能最佳,T50为489.4℃,活化能Ea=112.5 kJ/mol,BET比表面积仍有81.6 m2/g,表现出较好的抗烧结性能。然后,用浆料涂覆法依次将第二载体(MA)和LSM4粉体涂覆在Fe-Cr-Al合金丝网上制得了丝网蜂窝催化剂。考察了第二载体及LSM/4MA粉体涂覆量的影响,在空速40000 h–1条件下测试了蜂窝催化剂的活性,结果表明,MA的最佳涂覆厚度约20mm,LSM/4MA的最佳涂覆量约为2.65 mg/cm2,甲烷转化率30%以上。     

溶胶-凝胶法制备La0.65Sr0.35MnO3及其光催化性能

采用溶胶-凝胶法合成了以Sr取代部分稀土金属La的La0.65Sr0.35MnO3样品,经XRD衍射分析确定其具有钙钛矿的晶体结构,并对其进行了光催化活性实验.结果表明:在700℃时,La0.65Sr0.35MnO3样品平均粒径为19 nm;在太阳光照射下,LA0.65Sr0.35MnO3降解亚甲基蓝溶液120 min时,其降解率达到90%.     

溶胶-自蔓延法制备La0.8Sr0.2Mn0.8Ni0.2O3催化剂的优化条件

采用溶胶-凝胶-自蔓延法合成较大比表面积的钙钛矿型复合氧化物La_0.8Sr_0.2Mn_0.8Ni_0.2O₃催化剂,研究了pH、苹果酸用量和焙烧温度对催化剂的影响,通过XRD、BET和SEM等分析手段对催化剂进行了表征。结果表明,pH=3、苹果酸用量为金属离子总物质的量2倍和焙烧温度600 ℃为最佳制备工艺条件。催化剂在低温对CO催化燃烧显示出良好的催化活性。     

Microstructure and electrical conductivity of La0.9Sr0.1 Ga0.8Mg0.2O2.85-Ce0.8Gd0.2O1.9 composite electrolytes for SOFCs

(100-x) wt.% La_0.9Sr_0.1 Ga_0.8Mg_0.2O_2.85 - x wt.% Ce_0.8Gd_0.2O_1.9 (x = 0, 5, 10, 20) electrolytes were prepared by solid-state reaction. The composition, microstructure, and electrical conductivity of the samples were investigated. At 300 ~ 600°C, the pure La_0.9Sr_0.1 Ga_0.8Mg_0.2O_2.85 electrolyte has a higher conductivity compared to the composite electrolytes, but at 650 ~ 800°C the 95 wt.% La_0.9Sr_0.1 Ga_0.8Mg_0.2O_2.85 - 5 wt.% Ce_0.8Gd_0.2O_1.9 composite electrolyte presents the highest conductivity, reaching 0.035 S cm⁻¹ at 800°C. The cell performances based on La_0.9Sr_0.1 Ga_0.8Mg_0.2O_2.85-Ce_0.8Gd_0.2O_1.9 electrolytes were measured using Sr₂CoMoO₆-La_0.9Sr_0.1 Ga_0.8Mg_0.2O_2.85 as anode and Sr₂Co_0.9Mn_0.1NbO₆ -La_0.9Sr_0.1 Ga_0.8Mg_0.2O_2.85 as cathode, respectively. At 800°C, the measured open-circuit voltages are higher than 1.08 V, and the maximum power density and current density of the fuel cell prepared with 95 wt.% La_0.9Sr_0.1 Ga_0.8Mg_0.2O_2.85 - 5 wt.% Ce_0.8Gd_0.2O_1.9 electrolyte reach 192 mW cm⁻² and 720 mA cm⁻², respectively.     

Mechanism and kinetic modeling for steam reforming of toluene on La0.8Sr0.2Ni0.8Fe0.2O3 catalyst

Reaction mechanism for steam reforming of toluene is proposed for La_0.8Sr_0.2Ni_0.8Fe_0.2O₃ perovskite catalyst. The proposed mechanism was derived from various characterization results such as temperature‐programmed desorption (TPD) and temperature‐programmed surface reaction (TPSR) water, TPSR toluene, TPD O₂ and in situ DRIFT of toluene decomposition, and steam reforming of toluene. Five kinetic models were developed based on the proposed dual‐site reaction mechanism using Langmuir–Hinshelwood approach. Subsequently, the parameters of the kinetic models were estimated by nonlinear least square regression. A good agreement was obtained between experimental and model predicted results for the rate determining step based on reaction between adsorbed aldehyde and adsorbed oxygen. The adsorbed aldehyde species is produced from the reaction between adsorbed C₂H₂ or CH₂ and adsorbed oxygen while the adsorbed oxygen species can come from the oxygen from water activation, lattice oxygen species, and/or the redox property of some metals such as Fe. This shows that the adsorbed oxygen species plays important role in this reaction. © 2014 American Institute of Chemical Engineers AIChE J 60: 4190–4198, 2014     

Flame Spray Synthesis of Nanoscale La0.6Sr0.4Co0.2Fe0.8O3–δ and Ba0.5Sr0.5Co0.8Fe0.2O3–δ as Cathode Materials for Intermediate Temperature Solid Oxide Fuel Cells

Electrochemical performance and degradation was analysed by conductivity measurements as well as thermogravimetric analysis (TGA) under different atmospheres. CO₂ was identified as a critical parameter in terms of carbonate formation from Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3–δ and causes a strong increase in the material resistivity, whereas La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ is unaffected. The oxygen exchange kinetic of both compositions is affected by CO₂ containing atmospheres.     

Preparation and catalytic performance of La0.8Sr0.2CoO3 supported on the mullite fiber ceramic

The perovskite-type La_0.8Sr_0.2CoO₃ supported on the mullite fiber porous ceramics was prepared by means of the impregnating method, and was then characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD); thus we can come to the conclusion that the perovskitetype composite oxidant can disperse on the surface of mullite fiber ceramics. The catalytic activity of the La_0.8Sr_0.2CoO₃ for NO and CO was evaluated. The effect of the doped 0.1 wt-% PdCl₂ on the catalytic activity of the perovskite-type La_0.8Sr_0.2CoO₃ was also discussed. The results show that the conversion rates of NO and CO respectively reaches 74.5% and 99% at 601°C without doped Pd, and both reach 100% at 350°C with a little doped Pd. __________ Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(9): 99–103 [译自: 华南理工大学学报 (自然科学版)]