Ce1-xGdxO2-x/2的溶胶-凝胶法合成及其性质

利用溶胶-凝胶法合成了Ce₁-xGdxO_2-x/2(x=0.1～0.6)系列固体电解质,系统地研究了其结构、热膨胀系数和导电性.XRD结果表明,160℃即完全形成立方萤石结构.由于溶胶-凝胶法合成的物质粒度均匀,颗粒小,故在较低温度(1300℃)时即可形成高致密样品,此温度明显低于传统的高温固相法烧结温度(1600～1650℃).高温X射线衍射测得Ce_0.8Gd_0.2O_1.9的热膨胀系数为8.125×10^-6K₁.阻抗谱表明,溶胶-凝胶法合成可减少或消除固体电解质的晶界电阻,600℃时Ce_0.8Gd_0.2O_1.9的电导率为5.26×10^-3S/cm,活化能E_a=0.82eV.     

二元析氧催化剂CoxCr1-xO3/2的制备及性能研究

用热分解法制得不同混合比例的二元金属氧化物催化剂Co_xCr_1-xO_3/2（x = 0,0.2,0.4,0.6,0.8,1）,使用SEM、XRD和XPS观察表征催化剂形貌、晶型和价态,使用线性扫描伏安、阶梯波伏安和恒电位测试电极活性、过电位和稳定性. 结果表明,该Co₃O₄和绿铬矿型Cr₂O₃混合物形成固溶体Co_xCr_1-xO_3/2. x = 0.2时,Co_0.2Cr_0.8O_3/2电极性能较单一Co₃O₄和Cr₂O₃电极好,在高电位（1.0 V vs. Ag/AgCl）,其电流强度是Co₃O₄的3.75倍,Cr₂O₃的15.2倍,其过电位（η = 0.0703 V）也较Co₃O₄（η = 0.6109 V）和Cr₂O₃（η = 0.435 V）小,催化性能最好,在强碱性溶液（pH=13）中有良好的稳定性.     

Nd3+-doped Li3V2(PO4)3 cathode material with high rate capability for Li-ion batteries

A series of Nd3+-doped Li3NdxV2àx(PO4)3(x = 0.00, 0.02, 0.05, 0.08 or 0.1) composites are synthesized by the rheological phase reaction method. The XRD results indicate that Nd3+ions have been successfully merged into a lattice structure. Doped samples show good electrochemical performance in high discharge rate and long cycle. In the potential range of 3.0–4.3 V, Li3Nd0.08V1.92(PO4)3exhibits an initial discharge capacity of 115.8 m Ah/g at 0.2 C and retain 80.86% of capacity retention at 2 C in the 51 st cycle.In addition, Li3Nd0.05V1.95(PO4)3holds at 100.4 m Ah/g after 80 cycles at 0.2 C with a capacity retention of92.4%. Finally, the CV test proves that the potential polarization of Li3Nd0.08V1.92(PO4)3decreased compared with the un-doped one.     

双核钼(Ⅴ)二乙基二硫代氨基甲酸络合物的歧化离解平衡及其离解常数

由于发生歧化离解,Mo₂O₃(S₂CNEt₂)₄的溶液不遵守Beer定律,我们测定了有关溶液的光吸收性质以及Mo₂O₃(S₂CNEt₂)₄的歧化离解常数,于15℃时数值为2.2×10^-4。     

Ce-Zr-O2上CuO分散性对CO氧化活性的影响

采用柠檬酸法制备了Ce-Zr-O₂固溶体, 并负载了过渡金属和贵金属Pt, 其中, 以Cu作为活性组分, 在CO氧化反应中表现出最高的活性, CO完全转化的温度约为120 ℃, 明显高于负载1%Pt(质量分数)催化剂的活性. 掺杂少量Zr到CeO₂(Ce_0.8Zr_0.2O₂)中对Cu基催化剂有非常好的促进作用. 分别采用等体积浸渍法(IW)、 沉淀沉积法(DP)、 水热法(HT)以及柠檬酸法(CA)制备了Cu负载质量分数为20%的Cu/Ce_0.8Zr_0.2O₂催化剂. 结果表明, 由沉淀沉积法制备的Cu/Ce_0.8Zr_0.2O₂催化剂的活性最高, 在100 ℃时, CO可完全转化. TEM结果表明, CuO物种很好地分散在Ce_0.8Zr_0.2O₂上. 吸附实验数据表明, Cu基催化剂上CO与O₂之间较弱的竞争吸附是其活性高于Pt催化剂的主要原因. Cu基催化剂上的氧空位对促进O₂的吸附具有重要作用, 也是影响CO低温氧化的重要因素之一.     

溶液中钪与草酸离子的配位作用

提钪工艺中常使草酸钪溶于过量草酸铵溶液中。但文献中有关钪与草酸离子配位作用的报导甚少。等用分光光度法测定了ScC₂O₄⁺配离子的稳定常数,而J·Stary则用分配法测定了SC(C₂O₄)₃^3-配离子的稳定常数,这些工作都没有对溶液中可能生成各级配离子进行研究。     

制备条件对Ru/Ce_(0.8)Zr_(0.2)O_2催化剂上CO_2甲烷化反应性能的影响

采用均相法制得Ce0.8Zr0.2O2载体,并以其为载体等体积浸渍制得一系列负载型Ru催化剂。在0.1 MPa、GHSV为10000 h-1、H2/CO2为3.5(物质的量比)的条件下,对催化剂进行评价。借助TG-DSC、BET、H2-TPR等技术对所制备的载体和催化剂进行表征,结果表明,500℃焙烧的载体具有适中的比表面积和孔径并形成了Ce-Zr固溶体,与载体形成弱相互作用的Ru能够显著提高催化剂的活性,适宜的还原方式能促进活性组分的均匀分布。采用500℃焙烧的载体浸渍Ru Cl3溶液,干燥后在400℃焙烧,并使用水合肼和H2两次还原后的催化剂活性最高,在290℃时,H2转化率可达到93.57%。     

甘氨酸-硝酸盐法制备中温SOFC电解质及电极材料

采用一种新的燃烧合成陶瓷粉末的方法--甘氨酸-硝酸盐法合成中温SOFC所有元件的初始粉体,电池的电解质材料是(CeO₂)x(SmO_1.5)_{1-x(x=0.9,0.85,0.8),阳极材料是掺(CeO2)0.8(SmO1.5)0.2(SDC)的NiO,阴极材料是SDC与La0.6Sr0.4Fe0.8Co0.2O3的复合材料.其中以(CeO2)0.9(SmO1.5)0.1为电解质的单电池性能最好,在750℃时短路电流密度为0.5A/cm²,最大功率密度达0.104W/cm².通过SEM结果分析,掺杂摩尔分数20%SmO1.5的电解质晶界非常明显,而掺杂10%的电解质晶界有很强的融合消失的趋势.}     

Studies on a New System of Lithium Fast Ion Conductors Based on Kaolinite and LiZr_2(PO_4)_3

ＳｔｕｄｉｅｓｏｎａＮｅｗＳｙｓｔｅｍｏｆＬｉｔｈｉｕｍＦａｓｔＩｏｎＣｏｎｄｕｃｔｏｒｓＢａｓｅｄｏｎＫａｏｌｉｎｉｔｅａｎｄＬｉＺｒ２（ＰＯ４）３ＨＵＡＮＧＪｉａｎ－ｄｏｎｇ＊＊,ＬＩＮＢｉｎ,ＷＡＮＧＷｅｎ－ｊｉ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈ...     

纳米晶(CeO2)1-x(BiO1.5)x固溶体的水热合成与离子输运性质研究

在240℃水热体系中首次合成出系列纳米晶固溶体(CeO₂)_1-x(BiO_1.5)_x(x=0.0～0.50).产物采用X射线衍射,扫描电子显微镜和X射线光电子能谱仪进行表征.Bi₂O₃在CeO₂中的固溶限约为50%.所有固溶体结晶属立方萤石结构,粒度范围为10～18nm.当Bi₂O₃掺杂量小于固溶限时,于800℃烧结不会导致结构转变.而对于(CeO₂)_0.5(BiO_1.5)_0.5,于800℃在空气中烧结将导致固溶限降低.Bi₂O₃含量低于固溶限时,固溶体只具有体电导,而(CeO₂)_0.6(BiO_1.5)_0.4的总电导可分为体电导和晶界电导.体电导为氧离子,而晶界为来自电极的银离子.     

Theoretical Exploration of Stereochemical Nonrigidity for RfCo（PF3）x（CO）4-x（Rf=CF3, C2F5, C3F7, x=0-4）

The stereochemical nonrigidity of RfCo（PF3）x（CO）4-x（Rf=CF3,C2F5,C3F7,x=0-4） was studied at the theoretical level of B3LYP/6-31 1＋G^＊ via Gaussian 09.The intramolecular rearrangements in these penta-coordinated compounds are mainly caused by the vibrations of perfluoroalkyl groups.All the barriers along the reaction coordinate are less than 66.9 kJ/mol,which indicates that the rearrangements are kinetically favorable and hard to elucidate by experiment.Besides,ligand PF3 is a ligand similar to CO,the energy difference between the reactant and product is small.     

纳米MgO掺杂改善LiNi1/3Co1/3Mn1/3O2正极材料

将氢氧化物共沉淀法制备的(Ni_1/3Co_1/3Mn_1/3)（OH）₂在500℃热处理5 h得到具有尖晶石结构、纳米尺寸的氧化物M₃O₄(M=Ni_1/3Co_1/3Mn_1/3).将其与LiOH及不同量的纳米MgO混合均匀,并在850℃热处理24 h制备了Li(Ni_1/3Co_1/3Mn_1/3)_1/xMg_xO₂（x=0,0.01,0.02,0.03,0.04,0.05）正极村料.随着Mg掺杂量的增大,正极材料的晶胞参数增大;少量的Mg掺杂增大了锂离子的扩散系数,而过度掺杂却使锂离子扩散系数有所降低,其中Li(Ni_1/3Co_1/3Mn_1/3)_0.98Mg_0.02O₂的锂离子扩散系数最大,其脱出和嵌入扩散系数分别为D_Li-dein=29.20×10^-11cm²·S^-1和D_Li-in=4.760×10^-11cm²·s^-1;其以3C倍率充放电的平均放电比容量为139.3 mAh·g^-1,比未掺杂的原粉约高9.5 mAh·g^-1;另外其循环性能也得到了大幅度改善.     

Improved electrochemical properties in the Li3Fe2(PO4)3 by titanium and vanadium doping

Ti⁴⁺ ions were introduced to the VO₄^3- substituted Li₃Fe₂(PO₄)₃ by sol-gel method. Simultaneous substitution of Ti⁴⁺ for Fe³⁺ and VO₄^3- for PO₄^3- in the Li₃Fe₂(PO₄)₃ resulted in a net improvement in the rate capability and cycling performance, as compared with the single Ti⁴⁺ or VO₄^3- substituted compound.     

ZnSO_4和La_2O_3作共修饰剂单金属Ru催化剂上苯选择加氢制环己烯

用沉淀法制备了单金属纳米Ru(0)催化剂,考察了ZnSO4和La2O3作共修饰剂对该催化剂催化苯选择加氢制环己烯性能的影响,并用X射线衍射(XRD)、X射线荧光(XRF)光谱、X射线光电子能谱(XPS)、俄歇电子能谱(AES)、透射电镜(TEM)和N2物理吸附等手段对加氢前后催化剂进行了表征.结果表明,在ZnSO4存在下,随着添加碱性La2O3量的增加,ZnSO4水解生成的(Zn(OH)2)3(ZnSO4)(H2O)x(x=1,3)盐量增加,催化剂活性单调降低,环己烯选择性单调升高.当La2O3/Ru物质的量比为0.075时,Ru催化剂上苯转化率为77.6%,环己烯选择性和收率分别为75.2%和58.4%.且该催化体系具有良好的重复使用性能.传质计算结果表明,苯、环己烯和氢气的液-固扩散限制和孔内扩散限制都可忽略.因此,高环己烯选择性和收率的获得不能简单归结为物理效应,而与催化剂的结构和催化体系密切相关.根据实验结果,我们推测在化学吸附有(Zn(OH)2)3(ZnSO4)(H2O)x(x=1,3)盐的Ru(0)催化剂有两种活化苯的活性位:Ru0和Zn2+.因为Zn2+将部分电子转移给了Ru,Zn2+活化苯的能力比Ru0弱.同时由于Ru和Zn2+的原子半径接近,Zn2+可以覆盖一部分Ru0活性位,导致解离H2的Ru0活性位减少.这导致了Zn2+上活化的苯只能加氢生成环己烯和Ru(0)催化剂活性的降低.本文利用双活性位模型来解释Ru基催化剂上的苯加氢反应,并用Hückel分子轨道理论说明了该模型的合理性.     

钾改性Mn/Ce0.65Zr0.35O2催化剂催化氧化甲苯

Volatile organic compounds (VOCs) are both harmful to human health and the environment; however, catalytic combustion offers a promising method for VOC purification because of its high efficiency without secondary pollution. Although manganese-based catalysts have been well studied for VOC catalytic oxidation, their catalytic activity at low temperature must be improved. Alkali metals as promoters have the potential to modulate the electronic and structural properties of the catalysts, improving their catalytic activity. Herein, a Ce_0.65Zr_0.35O₂ support was prepared by co-precipitation and MnO_x/Ce_0.65Zr_0.35O₂ catalysts were obtained through the incipient-wetness impregnation method. The catalytic properties of K-modified MnO_x/Ce_0.65Zr_0.35O₂ for toluene oxidation with different molar ratios of K/Mn were investigated. In addition, the catalysts were characterized by XRD, UV/visible Raman, Hydrogen temperature program reduction (H₂-TPR), Oxygen temperature programmed desorption (O₂-TPD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance FTIR spectroscopy (DRIFTS) experiments. The results showed that alkali metal doping with K significantly improved the catalytic activity. In particular, when the molar ratio of K/Mn was 0.2, the monolith catalyst Mn/Ce_0.65Zr_0.35O₂-K-0.2 exhibited the best performance with the lowest complete conversion temperature T₉₀ of 242 ℃ at a GHSV of 12000 h⁻¹. The XRD results suggested that MnO_x was uniformly distributed on the surface of the catalyst and that Mn⁴⁺ partially reduced to Mn³⁺ on the addition of K. The Raman spectrum demonstrated that with increasing K content, both the β- and α-MnO₂ phases coexisted on the Mn/Ce_0.65Zr_0.35O₂-K-0.2 catalyst, increasing the number of surface defect sites. The H₂-TPR experiment results confirmed that Mn/Ce_0.65Zr_0.35O₂-K-0.2 exhibited the lowest reduction temperature and good reducibility. From the O₂-TPD experiments, it was clear that Mn/Ce_0.65Zr_0.35O₂-K-0.2 contained the most surface adsorbed oxygen species and excellent lattice oxygen mobility, which benefitted the toluene oxidation activity. In addition, the XPS results suggested that the content of surface adsorbed oxygen species of the Mn/Ce_0.65Zr_0.35O₂-K-0.2 catalyst was the highest among all the tested samples. In addition, toluene-TPSR in N₂ as measured by in situ DRIFTs analysis demonstrated that available lattice oxygen was present in the Mn/Ce_0.65Zr_0.35O₂-K-0.2 catalyst. Therefore, the Mn/Ce_0.65Zr_0.35O₂-K-0.2 catalyst exhibited the best redox properties and oxygen mobility of the prepared samples and showed excellent activity toward toluene oxidation. Therefore, it was concluded that the addition of an appropriate amount of K improved the redox performance of the catalyst and increased the number of surface defect sites and mobility of the lattice oxygen of the catalyst as well as the concentration of the surface active oxygen species, thereby significantly improving catalytic ability.     

Synthesis and Characterization of Zinc Succinate, Zn(C4H4O4)

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｓｕｃｃｉｎａｔｅｉｏｎ (Ｃ4Ｈ4Ｏ4) 2 -(—ＯＯＣＣＨ2 ＣＨ2 ＣＯＯ— )ｉｓａｖｅｒｓａｔｉｌｅｌｉｇａｎｄｓｉｎｃｅｅａｃｈｏｆｔｈｅｆｏｕｒｔｅｒｍｉｎａｌｃａｒｂｏｘｙｌｏｘｙｇｅｎｓｉｓａｂｌｅｔｏｐａｒｔｉｃｉｐａｔｅｉｎｃｏｏｒｄｉｎａｔｉｏｎｔｏｃｅｎｔｒａｌｍｅｔａｌａｔｏｍ(ｓ)ｉｎａｄｄｉｔｉｏｎｔｏｔｈｅｆｌｅｘｉｂｉｌｉｔｙｏｆｔｈｅＣ—Ｃｂｏｎｅ .Ｓｕｃｈｃｏｏｒｄｉｎａｔｉｎｇｖｅｒｓａｔｉｌｉｔｙｈａｓｂｅｅｎｒｅｆｌｅｃｔｅｄｉｎｓｅｖｅ…     

Preparation and Electrochemical Performance of Cobalt-free Cathode Material Ba0.5Sr0.5Fe0.9Nb0.1O3-δ for Intermediate-temperature Solid Oxide Fuel Cells

Perovskite oxide Ba0.5Sr0.5Fe0.9Nb0.1O3-δ（BSFN） as a cobalt-free cathode for intermediate-temperature solid oxide fuel cells（IT-SOFCs） on the Ce0.5Sm0.2O1.9（SDC） and La0.9Sr0.1Ga0.8Mg0.23O3-δ（LSGM） electrolytes was prepared and investigated. The single phase BSFN oxide with a cubic perovskite structure and relatively high elec- trical conductivities was obtained after sintering at 1250℃ for 10 h in air. The BSFN cathode exhibited excellent chemical stability on the SDC and LSGM electrolytes at temperatures below 950 ℃. The area specific resistance of the BSFN cathode on the SDC and LSGM electrolytes were 0.024 and 0.021 Ω·cm2 at 800℃, respectively. The maximum power densities of the single cell with BSFN cathode in 300 μm-thick SDC and LSGM electrolytes achieved 414 and 516 mW/cm2 at 800℃, respectively. These results show that the BSFN material is a promising co- bait-free cathode candidate to be used in IT-SOFCs. A combination of the BSFN cathode and LSGM electrolyte is preferred owing to its excellent electrochemical performance.     

低温甲烷氧化偶联纳米SrTi_(0.975)Li_(0.025)O_(3-δ)催化剂的原位ESR和TPSR表征

采用溶胶-凝胶法制备纳米钙钛矿型复合氧化物催化剂SrTi1-xLixO3-δ(x=0、0.025、0.050),用微型催化反应评价装置结合XRD、TEM、原位ESR和程序升温表面反应(TPSR)等方法,研究甲烷氧化偶联(OCM)纳米SrTi1-xLixO3-δ催化剂结构和催化性能。结果表明,B位掺杂适量的低价Li+离子可优化纳米SrTiO3催化剂低温(~650℃)甲烷氧化偶联催化性能,Li+掺杂量为0.025时获得最高的甲烷转化率和C2选择性。与柠檬酸法制相同组成的常规催化剂相比,SrTi0.975Li0.025O3-δ纳米催化剂具有较优良的低温OCM催化性能和相同温度下更高的C2选择性。SrTi0.975Li0.025O3-δ纳米催化剂优良的催化性能与其表面原子配位不饱和存在F中心相关。     

One Dimensional Iron Molybdophosphate Anionic Chains with Different Structural Arrangements Reflecting a Flexibility Character

Structural comparison of a new compound[(bpp)₃H₆]Fe₂^IIIFe₂^IIMo₂₄^V(H₂PO₄)₈(HPO₄)₄(PO₄)₄O₄₈(OH)₁₂· (H₂O)₄·2H₂O(1)[bpp=1,3-di(4-pyridyl)propane] with our previously reported two compounds[(bpy)₃Fe^II]₃· Fe₂^IIIFe₂^IIMo₂₄^V(H₂PO₄)₈(HPO₄)₄(PO₄)₄O₄₈(OH)₁₂(H₂O)₄·12H₂O(2) and[(bpy)₃Fe^II]₂Fe^IIFe^IIIMo₁₂^V(H₂PO₄)₂(H_2-xPO₄)·(H_1+xPO₄)(HPO₄)₂(PO₄)₂O₂₄(OH)₆(H₂O)₂·9H₂O(x=0―1)(3)(bpy=2,2'-bipyridine), which all exhibit one-dimensional mixed-valence iron molybdophosphate anionic chains constructed by alternating connection of Fe^III ions and magic[Fe^II(Mo₆P₄O₃₁)₂] units, reveals that the non-hydrogen atomic ratios of Mo:Fe:P:O within the polymeric anionic chains are the same for all the three compounds, while the polymeric anionic chains of the different compounds bear different numbers of negative charges. And therefore there exist different numbers of counter cations per {Fe₂^III[Fe₂^II(P₁₆Mo₂₄^VO₁₂₄)]} unit found in the titled compounds. It discloses that not only are the spatial assembling of counter cations and polymeric inorganic chains of three compounds quite different, but also the O―Fe^III―O bond angles and Fe^III―O bond lengths of the three different inorganic chains exhibit small differences. What is more important is that such small changes in bond length and bond angle in the assemblage of Fe^III―O bonds lead to the considerable fluctuations of inorganic chains in their structural conformation within the three compounds, reflecting an interesting phenomenon of “flexibility" in the pure inorganic one dimensional mixed-valence iron molybdophosphate chains.     

Synthesis and Characterization of Manganese-copper Spinel Ferrite Powders

Magnetic Mn_1-xCu_xFe₂O₄(x=0.2, 0.5, 0.8 and 1.0) nanoparticles were synthesized by single citrate precursor method. The samples were characterized by powder X-ray diffraction, vibrating sample magnetometry and electron paramagnetic resonance(EPR). For samples with a low copper content(x<0.5), the copper ions have a tendency to occupy and substitute the Fe³⁺ at the tetrahedral(A) sites. For samples with a high copper content(x>0.5), most Cu²⁺ enter into the octahedral(B) sites. Transfer of Fe³⁺ from octahedral sites to tetrahedral sites leads to the decrease of the saturation magnetization. Maximum coercivity is observed for CuFe₂O₄ nanoparticles due to the strengthened magnetic anisotropy arisen from the Jahn-Teller effect of the octahedral copper ions. The dependence of magnetic properties of Mn_0.8Cu_0.2Fe₂O₄ nanoparticles on calcination temperature was investigated. The cation distribution in Mn_0.8Cu_0.2Fe₂O₄ is sensitive to the calcination temperature.