无机添加物对β PbO2-SPE复合膜电极结晶形貌及电催化活性的影响

化学镀制βPbO2-SPE复合膜电极的过程中加入无机添加物Fe2 和Co2 可以改善膜电极的电催化性能。SEM和XRD测试表明,加入Fe2 和Co2 可使镀层结晶更细小、沉积更均匀、致密。阳极极化曲线测试证明,βPbO2/Co-SPE电极电化学反应的速度最快,另两种电极的反应速度相近。苯酚溶液中循环伏安测试证明,镀层析氧电位从高向低的排序是βPbO2/Co>PbO2/Fe>βPbO2,βPbO2/Co-SPE电极最适合用于降解有机污染物。电化学降解苯酚过程证明,βPbO2/Co-SPE电极的电催化活性远高于其它两种电极。     

MPCVD掺硼金刚石薄膜的制备及Ti/BDD 电极上对硝基酚的阳极氧化测试

采用微波等离子体技术在CH4-H2-C2H6气体条件下制备了钛基掺硼金刚石薄膜.四点探针法测得薄膜电阻率在零掺杂时为1×1012Ω*cm ,当反应气源中B/C上升为5×10-3时电阻率降至5×10-3 Ω*cm.扫描电镜显示掺硼金刚石具有完整晶型和致密结构.拉曼光谱观察到金刚石结构在掺杂前后发生明显改变.采用循环伏安测试了Ti/BDD电极的电化学参量,并与PbO2, Sn-Sb and PbO2-Er三种电极进行阳极氧化对-硝基酚的对比实验.结果表明,在Ti/BDD电极上,对-硝基酚的总有机碳去除率接近100;,远高于其它三种电极.     

CuO-NiO/SnO2光催化剂的制备、表征及产氢性能

采用溶胶-凝胶法制备纳米SnO2,通过浸渍法制备CuO-NiO/SnO2光催化材料,采用XRD、UV-Vis DRS、TEM及HRTEM对其结构、形貌及光吸收性能进行表征。在紫外灯照射下,以无水乙醇为电子给体,详细考察了CuO掺杂量、NiO掺杂量、乙醇浓度等对SnO2光催化产氢性能的影响。研究结果表明:5%CuO-7%NiO/SnO2的光催化产氢性能最佳,约是同条件下纯SnO2产氢性能的2.8倍;最优乙醇浓度约为1.2 mol/L。     

多孔陶瓷负载TiO2光催化降解甲基橙溶液的研究

采用有机先驱体浸渍法及无压烧结工艺,制备了Al2O3多孔陶瓷载体。利用溶胶-凝胶法在多孔陶瓷上负载Sm3+掺杂Ti O2光催化材料。研究了煅烧温度、涂层次数等工艺因素对多孔陶瓷负载Ti O2光催化降解甲基橙溶液的影响规律。结果表明,借助于多孔陶瓷高的气孔率,Ti O2负载在Al2O3颗粒表面或进入颗粒间的孔隙内,使材料具有较大的比表面积。掺入Sm3+使材料的光催化活性提高。在煅烧温度为600℃、四次涂层、甲基橙溶液p H值为2时,多孔陶瓷负载Ti O2光催化降解甲基橙溶液效果最佳。     

SnO2/氮掺杂石墨烯纳米复合材料的制备及其电化学性能研究

采用温和的水热法在氧化石墨烯(GO)片层上原位生长纳米SnO2颗粒, 通过氨水调节体系pH值并对石墨烯进行掺氮,成功制备出了SnO2/氮掺杂石墨烯(N-rGO)和SnO2/石墨烯(rGO)纳米复合材料,并对它的电池和电催化性能进行研究.XRD和SEM等分析结果表明,SnO2颗粒均匀地分布在N-rGO和rGO表面,粒径分别为50 nm和100 nm左右.进一步的TEM结果表明,SnO2颗粒是由更细小的粒径为5~7 nm SnO2颗粒所组成的二次团聚体.半电池性能测试结果表明:在100 mA/g电流密度下,SnO2/N-rGO和SnO2/rGO的可逆容量分别为901 mAh/g、756 mAh/g,比同等条件下纯的纳米SnO2高6.0和4.9倍;在2 A/g的高电流密度放电情况下, SnO2/N-rGO和SnO2/rGO的放电比容量分别可以达到619 mAh/g和511 mAh/g,表现出优异的倍率性能.电催化性能测试表明:SnO2/N-rGO的催化活性要高于SnO2/rGO,催化氧还原反应(ORR)主要按照四电子转移过程进行,为非铂催化剂的研究提供了一个新的思路.     

Sn1-x-yMnxSbyO2体系固溶体的相关系及形成机制

本文采用化学共沉淀法制备一系列配比的三元 Sn1-x-yMnxSbyO2(y=0.05)固溶体,利用 XRD、TG-DTA 等分析了在 600～1000℃退火温度下的固溶体物相组成,并根据分析结果绘制了该固溶体在固相线下的相图,进而探讨了 Sn1-x-yMnxSbyO2(y=0.05)固溶体的形成机制.结果表明:在600～1000℃退火温度下,Sn0.9Mn0.05 Sb0.05O2 固溶体只存在四方金红石相的SnO2物相,锑和锰主要以Sb5+、Mn3+、Mn4+的形式进入SnO2晶格形成有限固溶体;Sn0.7Mn0.25Sb0.05O2 和 Sn0.6Mn0.35Sb0.05O2 固溶体在 700℃、800℃出现了立方相方铁锰矿型 Mn2O3,1000℃出现了四方相黑锰矿型 Mn3O4,Sn0.6Mn0.35Sb0.05O2 固溶体在1000℃时还出现Sb3+Sb5+O4 物相;固相线下 Sn1-x-yMnxSbyO2(y=0.05)固溶体相图包括六个区域,其中富含锡的(Sn,Mn,Sb)O2ss 区域是唯一的单相区,锰和锑主要分别以 Mn2O3 和Sb2O5 的形式溶入 SnO2 晶格中,并达到饱和.(Sn,Mn,Sb)O2ss 固溶体氧化物可作为良好导电性和耐腐蚀性的阳极中间层材料.     

光敏化La2O3/TiO2催化剂的制备及其光催化性能研究

采用溶胶-凝胶法和水热法制备了La2O3/Ti O2复合物,将此种La2O3/Ti O2复合物利用叶绿素提取液浸泡后,制得了光敏化La2O3/Ti O2复合物,并采用透射电子显微镜、X-射线衍射仪、比表面积测定仪和紫外-可见分光光度计等对样品进行了表征。结果表明:La2O3/Ti O2催化剂的颗粒粒径在3~10 nm之间,BET比表面积为173.53 m2/g,光敏化La2O3/Ti O2复合物具有较好的可见光响应性能。在可见光下研究了几种光催化剂对水中六价铬离子的光催化还原效果,光催化结果表明:以光敏化La2O3/Ti O2复合物为催化剂,在可见光下光催化还原含Cr6+废水180 min后,Cr6+脱除率达到78.7%。     

热处理温度对Fe掺杂纳米ZnO/SnO2催化剂粉体的光催化性能的影响

以SnCl4.5H2O、ZnNO3.6H2O、HCl、NaOH、FeCl3.6H2O为原料,采用共沉淀法制备Fe掺杂纳米ZnO/SnO2复合催化剂粉体,以溶液降解甲基橙反应为模型,借助透射电镜(TEM)、X射线衍射(XRD)测试仪等研究了热处理温度对0.2wt%Fe-Zn4Sn1(ZnO/SnO2=4/1(物质的量比))复合催化剂(简为:FZS)粉体催化活性和结构的影响。结果表明:随着热处理温度的升高,光催化活性先升高后降低,热处理温度为650℃时所得的FZS粉体的光催化活性达到最高,对甲基橙的降解率为89.63%(紫外光照50 min)。随着热处理温度升高,FZS粉体的粒径逐渐增大,分散性仍然较好。当热处理温度达到750℃时,随着热处理温度的升高,FZS粉体团聚现象明显,比表面积急剧减小,使得光催化活性降低。在热处理温度高于850℃时,样品中出现Zn2SnO4晶体,也使得光催化活性降低。     

CuO/SnO2/TiO2复合光催化剂的制备及光催化性能

采用硬脂酸法制备了CuO/SnO2/TiO2复合光催化剂,采用XRD及TG-DTA分析对其物相和热稳定性进行了表征,并通过苯酚的光催化降解行为对所制备催化剂的活性进行了评价.结果表明,经500 ℃热处理的CuO/SnO2/TiO2复合光催化剂属于单一的锐钛矿相,且铜、锡氧化物的引入抑制了TiO2的结晶和晶粒的生长.当催化剂组成为Cu:Sn:Ti=0.25:5:100(物质的量比),焙烧温度为500 ℃,催化剂投加量为0.5 g·L-1,溶液pH为4.0时,经3 h光催化反应苯酚的降解率达97.1;.     

Tb3+-Eu3+共掺杂2ZnO·2.2B2O3·3H2O的制备和发光性能

采用水热法合成了Tb3+和Eu3+共掺的2ZnO.2.2B2O3.3H2O红色荧光粉。通过固定Eu3+的掺杂浓度为3%(物质的量比:Eu∶Zn=3%),改变Tb3+的掺杂浓度(2%～15%),研究Tb3+掺杂浓度对红色荧光粉晶相结构和光学性能的影响。用X射线衍射和荧光光谱仪对样品的结构和发光性能进行表征,结果表明:随着Tb3+掺杂浓度的升高,样品由晶态向无定形的玻璃态转变;Eu3+的发光强度也逐渐增强;Tb3+与Eu3+之间存在能量传递的过程,且当采用不同的激发波长(220 nm和393 nm)激发时,其能量传递的过程也不一样。     

Ionic conduction in As2S3---Ag2S, GeS2---GeS---Ag2S and P2S5---Ag2S glasses

The glass-forming region in the system P---S---Ag was determined and density, thermal expansion, dc conductivity and the transport number of Ag ions were measured for P₂S₅---Ag₂S glasses found in the P---S---Ag system. The results for the transport number measurement show that P₂S₅---Ag₂S glasses are purely ionic conductors owing to the Ag ion migration, like most of the As₂S₃---Ag₂S and GeS₂---GeS---Ag₂S glasses reported previously. Glass structure and ionic conduction processes in As₂S₃---Ag₂S, GeS₂---GeS---Ag₂S and P₂S₅---Ag₂S glasses are discussed, based on their ionic conductivity and density data. The structural concept of -Ag₂S was applied to these glasses, which suggests that the Ag ions in the glasses are distributed in the available Ag ion sites in the non-conducting framework composed of both S anions and As, Ge or P cations. In each system the ionic conductivity increases linearly with increasing Ag⁺/total cation (%) in glass composition, the determining factor being the activation energy for ionic conduction alone. Thus, the activation energy in these glasses depends predominantly upon the molar ratio of Ag ions to total cation in the glass, irrespective of the kind of system. Small differences in the activation energy among the three systems can be interpreted as arising from differences in the field strength of As, Ge and P cations.     

Spectroscopic properties of Er-doped Na2O-Sb2O3-B2O3-SiO2 glasses

Spectroscopic properties of Er³⁺-doped Na₂O-Sb₂O₃-B₂O₃-SiO₂ glasses have been investigated for developing 1.5-μm broadband fiber amplifiers. An intense 1.5-μm near infrared emission with a broad full width at half maximum (FWHM) of 88 nm has been obtained for Er³⁺-doped 5Na₂O-20Sb₂O₃-35B₂O₃-40SiO₂ glass upon excitation with a 980 nm laser diode. The obtained emission cross-section of the ⁴I_13/2 → ⁴I_15/2 transition and the lifetime of the ⁴I_13/2 level of Er³⁺ ions are 6.8 × 10⁻²¹ cm² and 0.36 ms, respectively. It is noted that the product of the emission cross-section and the FWHM of the glass, σ_e × FWHM, is as great as 598.4 × 10⁻²¹ cm² nm, which is comparable or higher than that of Er³⁺-doped bismuth-based and tellurite-based glasses. These special optical properties encourage in identifying them as important materials for potential applications in high performance optics and optical communication networks.     

Phase separation and crystallization in the system SiO2-Al2O3-P2O5-B2O3-Na2O glasses

The phase separation and crystallization behavior in the system (80 − X)SiO₂ · X(Al₂O₃ + P₂O₅) · 5B₂O₃ · 15Na₂O (mol%) glasses was investigated. Glasses with X = 20 and 30 phase separated into two phases, one of which is rich in Al₂O₃-P₂O₅-SiO₂ and forms a continuous phase. Glasses containing a larger amount of Al₂O₃-P₂O₅ (X = 40 and 50) readily crystallize and precipitates tridymite type AlPO₄ crystals. It is estimated that the phase separation occurs forming continuous Al₂O₃-P₂O₅-SiO₂ phase at first, and then tridymite type AlPO₄ crystals precipitate and grow in this phase. Highly transparent glass-ceramics comparable to glass can be successfully obtained by controlling heat treatment precisely. The crystal size and percent crystallinity of these transparent glass-ceramics are 20-30 nm and about 50%, respectively.     

Growth of single crystals of NaH2PO4 (NaDP), NaH2PO4 · H2O (NaDP · H2O), and NaH2PO4 · 2H2O (NaDP · 2H2O) sodium dihydrogenphosphate based on the analysis of the Na2O-P2O5-H2O phase diagram

The crystallization conditions for the NaH₂PO₄, NaH₂PO₄ · H₂O, and NaH₂PO₄ · 2H₂O solid phases have been established from the analysis of the phase diagram of solubility of the ternary Na₂O-P₂O₅-H₂O system in the temperature range from 0 to 100°C. Based on these data, the methods for growing sodium dihydrogenphosphate single crystals of the above compositions are developed. The initial components for preparing mother solutions were H₃PO₄ and NaOH solutions taken in certain weight ratios. For the first time, NaDP, NaDP · H₂O, and NaDP · 2H₂O single crystals were grown on a seed by the method of temperature decrease. The habits of the NaDP and NaDP · H₂O single crystals are determined. __________ Translated from Kristallografiya, Vol. 47, No. 5, 2002, pp. 937–944. Original Russian Text Copyright ? 2002 by Soboleva, Voloshin.     

Thermo-optic properties of B2O3 doped Li2O-Al2O3-SiO2 glass-ceramics

Reduction in the temperature coefficient of the optical path length, dS/dT of Li₂O-Al₂O₃-SiO₂ glass-ceramics with near-zero thermal expansion coefficient was attempted using control of the temperature coefficient of electronic polarizability, ?, and the thermal expansion coefficient, α. The dS/dT value of 2.6 mol% B₂O₃-doped glass-ceramic was 12.5  × 10⁻⁶/°C, which was 0.9 ×  10⁻⁶/°C smaller than that of B₂O₃-free glass-ceramic. On the other hand, reduction in dS/dT through B₂O₃ doping was not confirmed in precursor glasses. Results showed that reduction in dS/dT of the glass-ceramic through B₂O₃ doping is caused by the reduction in ?. The reduction in ? from B₂O₃ doping was probably attributable to numerical reduction in non-bridging oxide ions with larger ? value by the concentration of boron ions in the residual glass phase. In addition, application of hydrostatic pressure during crystallization was effective to inhibit precipitation of β-spodumene solid solution, which thereby decreases dS/dT. The dS/dT value of B₂O₃-doped glass-ceramic crystallized under 196 MPa was 11.7 ×  10⁻⁶/°C. That value was slightly larger than that of silica glass. The α value of this glass-ceramic was smaller than that of silica glass.     

Electron diffraction RDF analysis of amorphous As2Se3,AAs2Se2Te,As2SeTe2 and As2Te3 films

The local order in amorphous films of As₂Se₃, As₂Se₂Te, As₂SeTe₂, and As₂Te₃ has been examined by scanning electron diffraction with direct recording of the intensity of the elastically scattered electrons. The radial distribution functions indicate that there is a systematic increase in mean nearest neighbor distance as the Te concentration is increased, butthe mean coordination number increases slightly around 2.4. Pair function calculation of models shows that the 3-aand 2-fold coordinations of arsenic and chalcogens are retained in these glasses and the interatomic distances are close to those predicted from the Pauling covalent atomic radii of the constituent atomic species. The short range order appears to be similar in amorphous and crystalline As₂Se₃, but different in the case of As₂Te₃ as found by previous workers on bulk materials.     

Thin SiO2---TiO2---ZrO2 films from alkoxide solutions

Different solutions containing alkoxides of silicon, titanium, and zirconium have been prepared. Some of their properties like the time dependent viscosity and the gelling time have been measured and are reported here for different H₂O, HCl, ethanol and/or formamide contents. Microscope slides have been dip coated in these solutions. After baking, film thickness and chemical durability have been determined.

In order to get good SiO₂---TiO₂---ZrO₂ glass coatings, the withdrawal speed should not exceed 5 cm/min unless the viscosities of the solutions are reduced by the addition of ethanol. By such a dilution, the film thickness could also be reduced, while the addition of formamide caused a delayed increase of the viscosity and increased gelling times. For this reason, solutions containing formamide can be used for longer periods. The chemical durability of the substrates against boiling NaOH solution is enhanced by the SiO₂---TiO₂---ZrO₂ glass coatings.     

Precipitation of In2O3 nano-crystallites from glasses in the system Na2O/B2O3/Al2O3/In2O3

Glasses in the system Na₂O/B₂O₃/Al₂O₃/In₂O₃ were melted and subsequently tempered in the range from 500 to 700 °C. Depending on the chemical composition, various crystalline phases were observed. From samples without Al₂O₃, In₂O₃ could not be crystallized from homogeneous glasses, because either spontaneous In₂O₃ crystallization occurred during cooling, or other phases such as NaInO₂ were formed during tempering. The addition of alumina, however, controlled the crystallization of In₂O₃. Depending on the crystallization temperature applied, the crystallite sizes were in the range from 13 to 53 nm. The glass matrix can be dissolved by soaking the powdered glass in water. This procedure can be used to prepare nano-crystalline In₂O₃-powders.     

The effect of composition on UV-vis-NIR spectra of iron doped glasses in the systems Na2O/MgO/SiO2 and Na2O/MgO/Al2O3/SiO2

Glasses with the compositions xNa₂O · 10MgO · (90 − x)SiO₂, 10Na₂O · xMgO · (90 − x)SiO₂, 5Na₂O · 15MgO · xAl₂O₃ · (80 − x)SiO₂, xNa₂O · 10MgO · 10Al₂O₃ · (80 − x)SiO₂, 10Na₂O · 10MgO · xAl₂O₃ · (80 − x)SiO₂, 10Na₂O · 5MgO · 10Al₂O₃ · (80 − x)SiO₂ were melted and studied using UV-vis-NIR spectroscopy in the wavenumber range from 5000 to 30 000 cm⁻¹. At [Al₂O₃] > [Na₂O], the UV-cut off is strongly shifted to smaller wavenumbers and the NIR peak at around 10 000 cm⁻¹ attributed to Fe²⁺ in sixfold coordination gets narrower. Furthermore, the intensity of the NIR peak at 5500 cm⁻¹ increases. This is explained by the incorporation of iron in the respective glass structures.     

Refractive index-structure correlations in Na2O-Al2O3-SiO2 glasses

The current structural models have been used to analyse the refractive index data of Na₂O-Al₂O₃-SiO₂ glasses (Al₂O₃/Na₂O?1). The SiO₂ content is the sole factor that controls the refractive index. Values could be obtained for the factors with which each structural unit contributes in the refractive index. The content of Al₂O₃ or Na₂O has no effect on the refractive index. The factors (differential refraction) are constant and do not change with composition. They have the same values for Na₂O-SiO₂ glasses. The differential refraction of a structural unit increases linearly with increasing the number of non-bridging oxygen ions. The difference of the contribution to the refractive index from a silicate unit to the next equals to a half of that for AlO₄ tetrahedron. The effect could be attributed to the change in both the concentration and differential refraction of structural units. The obtained factors for the structural units are useful in calculating the refractive index with a high degree of accuracy.