TiO_2/SiO_2复合材料的制备与表征

以钛酸四丁酯和正硅酸乙酯为原料,采用溶胶凝胶法和水解法相结合,在室温下制备了两种形态的TiO2/SiO2复合材料.采用透射电镜、傅里叶红外光谱、X射线衍射和紫外-可见光谱等测试方法对所得复合材料进行了表征,并对其光催化降解甲基橙溶液的性能进行了研究.结果表明:对TiO2进行表面处理制备的TiO2/SiO2复合材料比以SiO2为载体制备的TiO2/SiO2复合材料在光催化和抗紫外线性能上更优异.     

静电自组装制备纳米TiO2/SiO2光催化材料

采用静电自组装方法制备了纳米TiO2/SiO2光催化材料。采用巯丙基三甲氧基硅烷偶联剂对SiO2进行干法改性,采用双氧水/冰醋酸将偶联剂巯基基团氧化为磺酸基基团。在正负电荷的吸引下,带负电荷的SiO2与带正电荷的钛聚合阳离子自发地组装在一起,经一定温度热处理得到纳米TiO2/SiO2光催化材料。采用XRD、FTIR、PL、UV-Vis DRS、SEM和ICP等对材料进行了分析和表征。采用甲基橙溶液评价材料的光催化性能。结果表明:SiO2促使锐钛矿的形成,抑制锐钛矿向金红石的转变,减小TiO2的晶粒尺寸,使得TiO2光吸收波长发生蓝移。TiO2与SiO2通过Si-O-Ti键发生结合。采用静电自组装方法制备的材料中TiO2的含量高于传统方法,导致材料的光催化性能有所提高。     

CNTs/TiO2多孔复合膜的组装及光催化性能

提出了一种在掺氟的SnO2(FTO)导电玻璃上组装碳纳米管(CNTs)/Fe-Ni/TiO2多孔复合膜光催化剂的新方法.采用喷涂热解法(SPD)将掺杂镍和铁的含有嵌段聚合物P123的二氧化钛前驱体溶胶涂覆在FTO导电玻璃上,制备Fe-Ni/TiO2多孔膜,再采用化学气相沉积法(CVD)在Fe-Ni/TiO2膜上原位生长CNTs,得到CNTs/Fe-Ni/TiO2多孔复合膜光催化剂.CNTs/Fe-Ni/TiO2复合膜具有多级孔结构特征,在TiO2表面原位生长的CNTs不但具有较好的石墨化结构,且CNTs较均匀地分布在整个膜层的孔中.考察了CNTs/Fe-Ni/TiO2复合膜光催化剂的结构和性能,并通过降解甲基橙溶液评价了复合膜的光催化活性.结果表明,CNTs的复合及铁和镍的掺杂等改性显著提高了TiO2膜材料的光催化活性.     

碳纳米管/TiO_2复合材料的制备及表征研究

采用溶胶-凝胶法和水热合成法,制备出碳纳米管/TiO2(CNTs/TiO2)复合材料。通过X-射线衍射仪(XRD)、扫描电子显微镜(SEM),紫外-可见漫反射光谱(UV-Vis),荧光光谱(LS)检测CNTs/TiO2的晶型及形貌。结果表明:锐钛矿相TiO2纳米颗粒负载在碳纳米管的管壁上,CNTs/TiO2在紫外-可见光波长范围均有较好的吸收性能。在灭菌灯照射下,以甲基橙溶液为降解目标,CNTs/TiO2复合材料对甲基橙溶液的降解有高的光催化活性,180 min内降解率达到85%以上。     

Fe2O3/TiO2纳米管的制备及其光电催化降解染料废水性能

采用阴极电沉积和阳极氧化法制备了Fe2O3改性TiO2纳米管(Fe2O3/TiO2-NTs)电极,运用场发射扫描电子显微镜、透射电子显微镜、X射线衍射和紫外-可见漫反射光谱等手段对其进行了表征,考察了其光电化学性能,并研究了复合电极光电催化降解甲基橙染料废水的反应性能.结果表明,Fe2O3的负载成功地将TiO2-NTs的光响应区间拓宽到可见光区域,Fe2O3/TiO2-NTs复合电极的光电流密度达到TiO2-NTs电极的3倍.在光电催化反应中,Fe2O3/TiO2-NTs复合电极对甲基橙的脱色效果明显优于TiO2-NTs电极,以Fe2O3/TiO2-NTs为阳极,光照5min,甲基橙溶液的脱色率可达90%以上.     

三维有序大孔Ag/ZrO2-TiO2：制备及紫外光催化降解染料和水杨酸性能

采用聚苯乙烯(PS)微球作为模板剂,经溶胶-凝胶及煅烧后处理的方法制备了三维有序大孔(3DOM)复合材料Ag/ZrO2-TiO2。通过FTIR、XRD、XPS、N2吸附-脱附和SEM-EDS等对其进行了表征。结果显示,经PS微球作用后的复合材料Ag/ZrO2-TiO2具有锐钛矿晶型结构,其Ag以单质形式存在。该复合材料的孔结构高度有序,属三维有序大孔,平均孔直径为120 nm,孔壁由紧密堆积的Ag/ZrO2-TiO2纳米晶粒组成,孔收缩率约为40%。该复合材料表现出较好的紫外光催化降解水杨酸和甲基橙等染料性能,其活性明显高于商用光催化剂(Degussa P-25)、Ag/ZrO2-TiO2和3DOM ZrO2-TiO2,在90 min内对甲基橙的降解率达80.1%。     

微波助离子液体中纳米TiO2／PMMA复合材料的制备及光催化性能

微波加热法合成离子液体[Bmim]BF4,并以该离子液体为反应介质,在微波辐射条件下制备纳米TiO2/PMMA复合材料.用XRD,IR和TG对该复合材料进行测试和表征;并在高压汞灯下用甲基橙溶液对其进行光催化降解性能测试.结果表明,制备TiO2/PMMA复合材料的最佳条件是:离子液体1.7mL,钛酸丁酯与MMA的体积比为3.4∶1.0,微波辐射功率600W、反应温度70℃、反应时间35min.并且用[Bmim]BF4作为反应介质,能够显著提高TiO2/PMMA复合材料的光催化活性,所制备的TiO2/PMMA复合材料不需要经过高温煅烧,就表现出极高的光催化活性;TiO2负载PMMA后,复合材料的光催化活性得到了进一步的改善.该复合材料对甲基橙的降解率在1.5h就可达到98.4%,其活性明显优于未负载的纳米TiO2催化剂.     

TiO_2-SBA-15催化剂的制备、表征及光催化降解甲基橙

以钛酸四丁酯为钛源,以介孔分子筛SBA-15为载体,采用简单的方法制备TiO2-SBA-15催化剂,并采用FT-IR,XRD和N2吸附-脱附等方法对其进行表征.另外,将制备的TiO2-SBA-15催化剂应用于光催化降解甲基橙溶液,并讨论了钛含量、甲基橙浓度及溶液pH值对降解率的影响.结果表明:在钛酸四丁酯起始加入量为3.2mL,甲基橙浓度为10mg/L,溶液pH=3的条件下,TiO2-SBA-15光催化降解甲基橙的降解率可达到100%.     

SiO2负载的TiO2光催化剂可见光催化降解染料污染物

 采用酸催化溶胶-凝胶法制备了SiO2负载的TiO2光催化剂,考察了制备条件对负载型TiO2光催化剂的晶相、结构、比表面积和可见光催化活性的影响. 结果表明,采用SiO2为载体时,TiO2以纳米颗粒的形态分散在载体表面,负载型TiO2/SiO2催化剂的比表面积大、等电点低而且热稳定性能良好. 偶氮染料酸性橙7的可见光催化降解实验结果表明,染料污染物在催化剂表面的吸附是影响催化剂可见光催化活性的重要因素. 与试剂TiO2样品相比,负载型TiO2/SiO2光催化剂具有更好的光催化活性和沉降性能.     

SiO_2掺杂TiO_2催化超声降解甲基橙溶液

采用实验室合成的SiO2掺杂TiO2作为催化剂,以甲基橙超声降解反应为模型,研究了各种因素对SiO2掺杂TiO2催化超声降解甲基橙的影响.结果表明在SiO2掺杂TiO2催化剂作用下超声降解甲基橙的效果明显优于非掺杂的锐钛矿型TiO2的催化效果.SiO2掺杂TiO2催化剂用量在0.5～1.0g/L之间,超声波频率25kHz,输出功率1.0W/cm2,pH为1.0～3.0时,在甲基橙水溶液初始浓度20mg/L的条件下,80min,降解率达到了98%以上,COD的去除率也达到了99.0%.因此,SiO2掺杂TiO2催化超声降解有机污染物的方法具有很好的应用前景.     

CeO2改性Ag-V2O5/TiO2催化剂的甲基吡啶氧化脱甲基性能

以锐钛矿TiO_2为载体,考察了CeO_2改性对Ag-CeO_2-V_2O_5/TiO_2催化3-甲基吡啶氧化脱甲基性能的影响,并优化了催化剂组成与制备条件.结果表明:Ce掺杂改性不仅能够与V物种作用形成Ce VO_4,而且促进V_2O_5分散,改善活性组分的氧化还原性能,从而提高3-甲基吡啶脱甲基转化率与选择性,改善Ag-V_2O_5/TiO_2催化性能.适宜的催化剂组成为V_2O_5负载量15%,Ce/V的摩尔比0.33,Ag质量分数1.0%.过高的焙烧温度将导致TiO_2载体向金红石型转变,Ag-CeO_2-V_2O_5/TiO_2适宜制备条件为450℃焙烧4 h.     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

TiO2/SnO2复合光催化剂的耦合效应

采用改进的sol gel技术制备TiO2/SnO2耦合型半导体光催化剂,利用XRD、气相色谱 仪、粒度仪和表面光电压装置等研究了耦合型半导体光催化机理和光催化效率的影响因素, 并通过降解甲醛探讨其在空气污染治理中的作用.实验结果表明,添加20 ％(mol) SnO2的复 合半导体光催化剂,其光催化效率比纯TiO2高一倍以上.据实验结果和粒子紧密堆积原理,提 出强耦合效应和弱耦合效应的光催化反应模型,并用此模型较好地解释了TiO2/SnO2复合型半 导体光催化剂的光催化效率随SnO2含量变化规律.     

Conversion of NO in NO/N2, NO/O2/N2, NO/C2H4/N2 and NO/C2H4/O2/N2 Systems by Dielectric Barrier Discharge Plasmas

An experimental study on the conversion of NO in the NO/N₂, NO/O₂/N₂, NO/C₂H₄/N₂ and NO/C₂H₄/O₂/N₂ systems has been carried out using dielectric barrier discharge (DBD) plasmas at atmospheric pressure. In the NO/N₂ system, NO decomposition to N₂ and O₂ is the dominating reaction; NO conversion to NO₂ is less significant. O₂ produced from NO decomposition was detected by an on-line mass spectrometer. With the increase of NO initial concentration, the concentration of O₂ produced decreases at 298 K, but slightly increases at 523 K. In the NO/O₂/N₂ system, NO is mainly oxidized to NO₂, but NO conversion becomes very low at 523 K and over 1.6% of O₂. In the NO/C₂H₄/N₂ system, NO is reduced to N₂ with about the same NO conversion as that in the NO/N₂ system but without NO₂ formation. In the NO/C₂H₄/O₂/N₂ system, the oxidation of NO to NO₂ is dramatically promoted. At 523 K, with the increase of the energy density, NO conversion increases rapidly first, and then almost stabilizes at 93–91% of NO conversion with 61–55% of NO₂ selectivity in the energy density range of 317–550 J L⁻¹. It finally decreases gradually at high energy density. A negligible amount of N₂O is formed in the above four systems. Of the four systems studied, NO conversion and NO₂ selectivity of the NO/C₂H₄/O₂/N₂ system are the highest, and NO/O₂/C₂H₄/N₂ system has the lowest electrical energy consumption per NO molecule converted.     

Cr2(WO4)3和Cr2(MoO4)3的负热膨胀特性研究

用液相反应-前驱物烧结法制备了Cr₂(WO₄)₃和Cr₂(MoO₄)₃粉体。298～1 073 K的原位粉末X射线衍射数据表明Cr₂(WO₄)₃和Cr₂(MoO₄)₃的晶胞体积随温度的升高而增大, 本征线热膨胀系数分别为(1.274±0.003)×10^-6 K^-1和(1.612±0.003)×10^-6 K^-1。用热膨胀仪研究了Cr₂(WO₄)₃和Cr₂(MoO₄)₃在静态空气中298～1 073 K范围内热膨胀行为，即开始表现为正热膨胀，随后在相转变点达到最大值，最后表现为负热膨胀，其负热膨胀系数分别为(-7.033±0.014)×10^-6 K^-1和(-9.282±0.019)×10^-6 K^-1。     

Energetics of copper diphosphates – Cu2P2O7 and Cu3(P2O6OH)2

Differential scanning calorimetry and high temperature oxide melt solution calorimetry are used to study enthalpy of phase transition and enthalpies of formation of Cu₂P₂O₇ and Cu₃(P₂O₆OH)₂. α-Cu₂P₂O₇ is reversibly transformed to β-Cu₂P₂O₇ at 338–363 K with an enthalpy of phase transition of 0.15 ± 0.03 kJ mol⁻¹. Enthalpies of formation from oxides of α-Cu₂P₂O₇ and Cu₃(P₂O₆OH)₂ are −279.0 ± 1.4 kJ mol⁻¹ and −538.8 ± 2.7 kJ mol⁻¹, and their standard enthalpies of formation (enthalpy of formation from elements) are −2096.1 ± 4.3 kJ mol⁻¹ and −4302.7 ± 6.7 kJ mol⁻¹, respectively. The presence of hydrogen in diphosphate groups changes the geometry of Cu(II) and decreases acid–base interaction between oxide components in Cu₃(P₂O₆OH)₂, thus decreasing its thermodynamic stability.     

Spectroscopic properties of guanidinium zinc sulphate [C(NH2)3]2Zn(SO4)2 and ab initio calculations of [C(NH2)3]2 and HC(NH2)3

Raman and FTIR spectra of guanidinium zinc sulphate [C(NH₂)₃]₂Zn(SO₄)₂ are recorded and the spectral bands assignment is carried out in terms of the fundamental modes of vibration of the guanidinium cations and sulphate anions. The analysis of the spectrum reveals distorted SO₄²⁻ tetrahedra with distinct S–O bonds. The distortion of the sulphate tetrahedra is attributed to Zn–O–S–O–Zn bridging in the structure as well as hydrogen bonding. The CN₃ group is planar which is expressed in the twofold symmetry along the C–N (1) vector. Spectral studies also reveal the presence of hydrogen bonds in the sample. The vibrational frequencies of [C(NH₂)₃]₂ and HC(NH₂)₃ are computed using Gaussian 03 with HF/6-31G* as basis set.     

g-C3N4/Bi2O2CO32D纳米片复合材料的制备及可见光催化性能研究

采用自组装和化学沉淀法分别制得两种可见光驱动复合材料石墨相氮化碳/碳酸氧铋(g-C_3N_4/Bi_2O_2CO_3).采用X射线衍射光谱(XRD),紫外可见光谱、扫描电镜(SEM)、N_2吸附、电化学阻抗谱(EIS)和X射线光电子能谱(XPS)等分析手段对制备的催化剂进行了表征.结果表明,制备方法对纳米复合材料的晶相、形态及光学性能没有影响,但是影响g-C_3N_4和Bi_2O_2CO_3之间的相互作用力,导致光生电子-空穴对的分离速率存在显著差异.以可见光驱动苯酚和罗丹明B的降解实验为探针反应检测催化剂的光催化性能.实验结果表明自组装法得到的异质结催化剂中相互作用力更强,催化效果最高.O_2-是罗丹明B降解反应的主要活性物种,染料的光敏化、Bi_2O_2CO_3与g-C_3N_4综合效应,导致光生载流子电荷分离效率更高.     

EuZn2Si2 and EuZn2Ge2 Grown from Zn or Ga(ln)/Zn Flux

Single crystals of the novel ternary compounds EuZn₂Si₂ and EuZn₂Ge₂ were grown from pure gallium, indium, or zinc metal used as a flux solvent. Crystal properties were characterized using X-ray single-crystal analyses via Gandolfi and Weissenberg film techniques and by four-circle X-ray single-crystal diffractometry. The new compounds crystallize with ternary derivative structures of BaAl₄, i.e., EuZn₂Si₂ with ThCr₂Si₂-type (a=0.42607(2) nm, c=1.03956(5) nm, I4/mmm, R₁=0.038) and EuZn₂Ge₂ with CaBe₂Ge₂-type (a=0.43095(2) nm, c=1.07926(6) nm, P4/nmm, R₁=0.067). XAS and magnetic measurements on EuZn₂Si₂ and EuZn₂Ge₂ revealed in both compounds the presence of Eu²⁺ ions carrying large magnetic moments, which order magnetically at low temperatures. The magnetic phase transition occurs at T_N=16 and 7.5 K for the silicide and the germanide, respectively. In EuZn₂Si₂ there occurs a spin reorientation at 13 K and furthermore some canting of antiferromagnetically ordered moments below about 10 K. In EuZn₂Ge₂ a canted antiferromagnetic structure is formed just at T_N.     

SnO_2改性TiO_2对V_2O_5-WO_3/TiO_2催化剂结构和SCR性能影响

采用共沉淀法将SnO_2组分掺入到V_2O_5-WO_3/TiO_2催化剂载体TiO_2中,并通过多种物理化学手段,考察了不同SnO_2掺入量时对催化剂结构,表面分散物种和SCR性能影响.结果表明,SnO_2掺入到TiO_2中,元素Sn与Ti以Sn—O—Ti键形式相互作用,促进锐钛矿型TiO_2向金红石型TiO_2转变.在特定条件下,VO_x与WO_x物种和SnTi氧化物之间以V—O—Ti(Sn)和W—O—Ti(Sn)键形式相互作用,提高了VO_x物种可还原能力、促进了具有更多B酸酸量四面体WOx物种和V~(5+)物种生成.VW/SnTi催化剂表面VO_x物种与WO_x物种之间的相互作用更强.因此,VW/SnTi催化剂具有更好的SCR活性.