纳米TiO2介孔薄膜的模板组装制备研究

以TiCl₄为无机前驱体、三嵌段高分子共聚物EO₂₀PO₇₀EO₂₀为模板剂，在非水条件下制备了有序的锐钛矿TiO₂纳米晶介孔薄膜。通过热重-差热（TG-DTA）分析、X射线衍射（XRD）分析、原子力显微观察（AFM）及N₂吸附-脱附等测试对样品进行了表征。结果表明，薄膜具有均一的大介孔孔径（～10 nm），其BET比表面积为150 m²·g^-1，薄膜较宽的无机壁厚显著提高了介孔结构的热稳定性。通过红外（IR）光谱分析考察了溶胶-凝胶过程中发生的物理化学变化。在对薄膜表面形貌进行AFM观察的基础上初步探讨了嵌段共聚物EO₂₀PO₇₀EO₂₀对薄膜孔结构形成的导向机理。     

介孔炭的孔结构对其负载的Ru基氨合成催化剂性能的影响

采用模板法合成了介孔炭(MC),研究了其孔结构对其负载的Ru基氨合成催化剂Ba-Ru-K/MC性能的影响,采用N₂吸附脱附、扫描电镜和透射电镜等手段对介孔炭的孔结构进行了表征.研究发现,介孔炭载体的孔结构取决于模板剂的用量,当SiO₂/C质量比为1.0时,所制介孔炭比表面积最大.介孔炭负载的Ba-Ru-K催化剂活性与其介孔比表面积相关.在425℃,10MPa和10000h^-1条件下,合成氨的反应速率为139mmol/(g_cat·h).     

类钙钛矿甲酸盐的线性和非线性光学响应

采用原位溶剂热法合成了2种混合有机阳离子杂化甲酸盐(CH(NH₂)₂)[RE (HCOO)₄](RE=Y、Er)。这2种材料是同构的(手性空间群C222₁)，并具有有趣的类钙钛矿结构。进行了包括线性和非线性光学特性在内的光物理研究。(CH(NH₂)₂)[Y(HCOO)₄]和(CH(NH₂)₂)[Er(HCOO)₄]分别表现出5.59和5.61 eV的宽光学带隙，对应于222和221 nm的紫外吸收边缘。粉末倍频测量表明，(CH(NH₂)₂)[Y(HCOO)₄]和(CH(NH₂)₂)[Er(HCOO)₄]的倍频效应分别是基准KH₂PO₄(KDP)的0.32和0.37倍。测量得到(CH(NH₂)₂)[Y(HCOO)₄]和(CH(NH₂)₂)[Er(HCOO)₄]的双折射率分别为0.013和0.015。第一性原理研究表明，2个π共轭的(CH(NH₂)₂)⁺和HCOO^-基团是光学性质的主要贡献者。     

类钙钛矿甲酸盐的线性和非线性光学响应

采用原位溶剂热法合成了2种混合有机阳离子杂化甲酸盐(CH (NH₂)₂)[RE (HCOO)₄](RE=Y、Er)。这2种材料是同构的(手性空间群C222₁),并具有有趣的类钙钛矿结构。进行了包括线性和非线性光学特性在内的光物理研究。(CH (NH₂)₂)[Y (HCOO)4]和(CH (NH₂)₂)[Er (HCOO)₄]分别表现出5.59和5.61 eV的宽光学带隙,对应于222和221 nm的紫外吸收边缘。粉末倍频测量表明,(CH (NH₂)₂)[Y (HCOO)₄]和(CH (NH₂)₂)[Er (HCOO)₄]的倍频效应分别是基准KH₂PO₄(KDP)的0.32和0.37倍。测量得到(CH (NH₂)₂)[Y (HCOO)₄]和(CH (NH₂)₂)[Er (HCOO)₄]的双折射率分别为0.013和0.015。第一性原理研究表明,2个π共轭的(CH (NH₂)₂)⁺和HCOO^-基团是光学性质的主要贡献者。     

萘基桥联有机-无机杂化介孔材料的合成及其光学性质

以短链阳离子三聚表面活性剂C₁₀H₂₁N⁺(CH₃)₂(CH₂)₂N⁺(CH₃)(C₁₀H₂₁)(CH₂)₂N⁺(CH₃)₂C₁₀H₂₁]·3Br^?为结构导向剂, 通过2,7-二(3-三乙氧硅基氨丙酯基)萘(NIS)和四乙氧基硅烷(TEOS)共缩聚, 制备了有序的萘基桥联的杂化周期性介孔有机硅(PMOs). 样品通过X射线衍射(XRD)、高分辨透射电镜(HRTEM)、氮气吸附-脱附、差示扫描量热/热重分析(DSC/TGA)表征. 结果表明, 当NIS占NIS和TEOS总量40% (摩尔分数)时, 可以形成具有结晶态孔壁的有序介孔杂化材料. 当NIS含量低于或高于40%时, 分别形成无定形孔壁的有序介孔杂化材料和无孔杂化材料. 随着孔壁中萘基基团的增加, 由于有机基团之间π-π堆积作用增强, 杂化介孔材料显示良好的热稳定性. 由于在二氧化硅骨架中嵌入荧光萘基基团, 杂化有机-无机有序介孔材料显示了激基缔合物的光学行为. 随萘基基团含量的增加, 杂化材料的紫外吸收峰发生蓝移, 形成H聚集体; 由于聚集引起的荧光淬灭, 杂化材料的荧光量子产率明显降低.     

基于羧甲基纤维素钠制备氮掺杂多孔炭及其电容性能研究

以羧甲基纤维素钠(NaCMC)为碳源, 利用直接炭化工艺(无需进一步活化)制备多孔炭材料; 然后, 以CO(NH₂)₂为氮源, 形成了氮掺杂多孔炭材料. 氮的存在形式包括吡啶N、石墨N和吡咯N. 实验结果表明, 羧甲基纤维素钠与CO(NH₂)₂之间的配比可以有效控制氮存在形式、含量、样品的比表面积及孔的结构等. 样品的电化学性能测试表明, 氮掺杂后多孔炭材料的超电容性能得到了显著提升. 以carbon-N-1:20为例, 其比表面积可达858 m²·g^-1, 远高于未经氮掺杂carbon-blank 的463 m²·g^-1, 其质量比电容则由94.0 F·g^-1提高到了156.7F·g^-1.     

三组Pt- Ru/C催化剂前驱体对其性能的影响

分别以三组不同的Pt和Ru化合物为前驱体, 采用热还原法制备了Pt-Ru/C催化剂, 比较不同前驱体对催化剂性能的影响；通过XRD和TEM技术对催化剂的晶体结构及微观形貌进行了分析. 结果表明以H₂PtCl₆+RuCl₃和自制(NH₄)₂PtCl₆+Ru(OH)₃为前驱体的催化剂Pt和Ru没有完全形成合金状态, 在Pt(111)和Pt(200)之间有Ru(101)存在；以Pt(NH₃)₂(NO₂)₂和自制含钌化合物为前驱体制备的催化剂未检测出Ru金属或其氧化物的衍射峰, Pt-Ru颗粒在载体上分散均匀, 粒径最小, 为3.7 nm. 利用玻碳电极测试了循环伏安、记时电流和阶跃电位曲线, 考核了上述催化剂对甲醇阳极催化氧化活性的影响；结果表明：以Pt(NH₃)₂(NO₂)₂和自制含钌化合物为前驱体制备的催化剂对甲醇的电催化氧化活性最高, 循环伏安曲线峰电流密度达11.5 mA•cm^-2.     

表面活性剂-模板化法制备多级孔β沸石及其四氢萘加氢裂化制苯、甲苯、二甲苯的催化性能

采用表面活性剂-模板化法,分别以β-60和β-150为母体,选用十六烷基三甲基溴化铵(CTAB)作为表面活性剂,以一步和两步法制备了2种多级孔β沸石。以X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、N₂吸附-脱附测试和NH₃程序升温脱附(NH₃-TPD)测试对多级孔β沸石的物化性质进行分析。采用等体积浸渍法负载25%的WO₃制备成加氢裂化催化剂,考察其在四氢萘加氢裂化制备苯(B)、甲苯(T)和二甲苯(X)的催化性能。结果表明：相比于母体,一步制备样品的介孔孔容提高3倍以上,两步制备样品的介孔孔容提高1倍以上。另外,以β-60为母体,一步和两步制备样品的介孔均是无序的。一步制备样品的最高BTX收率是53%,两步制备样品的最高BTX收率是51%;然而,以β-150为母体,一步制备样品的介孔是无序的,而两步制备样品的介孔是有序的。一步制备样品的最高BTX收率是46%,两步制备样品的最高BTX收率是50%。因此,多级孔β沸石制备的加氢裂化催化剂的催化性能是由介孔的含量和有序度共同决定的。     

两种具有二次谐波响应的紫外透过氨基磺酸盐A(NH2SO3)(A=Li、Na)

通过简便的蒸发方法得到了 2种碱金属磺酸盐非线性光学(NLO)晶体, 即 Li(NH₂SO₃)和 Na(NH₂SO₃)。Li(NH₂SO₃)以极性空间群Pca2₁(编号 29)结晶。Li(NH₂SO₃)的结构可以描述为由[LiO₄]7-多面体通过共角连接与 NH₂SO₃^-四面体相互连接而形成的三维网络。Na(NH₂SO₃)以极性空间群 P2₁2₁2₁(编号 19)结晶。Na(NH₂SO₃)的结构可以描述为由扭曲的[NaO₆]^11-八面体通过共角连接与 NH₂SO₃^-四面体相互连接而形成的三维网络。紫外可见近红外光谱表明, Li(NH₂SO₃)和 Na(NH₂SO₃)分别具有 5.25 和 4.81 eV 的大光学带隙。粉末二次谐波发生(SHG)测量显示, Li(NH₂SO₃)和 Na(NH₂SO₃)的 SHG 强度分别为 KH₂PO₄的 0.32 倍和 0.31倍。第一原理计算证实, 非线性光学性能主要来自氨基磺酸阴离子和碱金属氧阴离子多面体的协同作用。     

介孔型铝酸镍纳米棒的制备及其催化氢化裂解甲苯性能

以NH₄HCO₃为造孔剂通过一步水热法成功合成了介孔型单晶NiAl₂O₄纳米棒, 并考察了不同反应条件对NiAl₂O₄形貌的影响. 实验结果表明反应时间、反应物浓度、NH₄HCO₃加入量对产物形貌具有关键作用. 用透射电子显微镜(TEM), 高分辨透射电子显微镜(HRTEM), 扫描电子显微镜(SEM)和X射线衍射仪(XRD)对NiAl₂O₄纳米棒的形貌、结构和组成进行表征, 并用氮气吸附-脱附法对其比表面积和孔径分布进行了研究. 以介孔型NiAl₂O₄纳米棒为催化剂, 在固定床反应器上对甲苯进行催化实验, 结果表明当水炭摩尔比为1.0、反应温度为700 ℃时, 400 min反应时间内甲苯平均转化率高达86.5%, 并具有较好的反应稳定性. 比较了直接沉淀法制备的纳米颗粒作为催化剂在甲苯氢化催化裂解中的催化性能. 结果表明水热法制备的棒状NiAl₂O₄催化剂比不用水热制备的催化剂催化活性要好. 初步探讨了介孔型NiAl₂O₄纳米棒的可能形成机理.     

染料敏化太阳能电池对电极La2Mo2O7复合MWCNTs非Pt催化剂的制备与性能

通过高温固相法对醋酸镧（C₆H₉O₆La·xH₂O）与高钼酸铵（（NH₄）₆Mo₇O₂₄·4H₂O）在一定条件下热解制备非Pt催化剂La₂Mo₂O₇（La₂O₃-2MoO₂）。进一步采用2种方法将La₂Mo₂O₇与多壁碳纳米管（MWCNTs）进行复合,一种是将La₂Mo₂O₇喷涂到MWCNTs表层之上得到La₂Mo₂O₇/MWCNTs,另一种是将两者均匀混合掺杂得到La₂Mo₂O₇@MWCNTs,再将上述2种复合材料应用于染料敏化太阳能电池对电极进行相应研究。通过扫描电子显微镜（SEM）表征了复合催化材料的微观形貌,X射线衍射（XRD）确定了微观结构。采用电流密度-光电压曲线、循环伏安,交流阻抗以及塔菲尔极化分析了材料的光电性能。实验结果表明在电解液I₃^-/I^-中,基于La₂Mo₂O₇/MWCNTs与La₂Mo₂O₇@MWCNTs的对电极,相同的条件下在光电池中获得的光电转换效率分别为6.09%和4.84%,明显高于MWCNTs的3.94%和La₂Mo₂O₇的0.87%。电极性能的提高可归因于La₂Mo₂O₇复合催化剂相对大的比表面积和高导电性。     

染料敏化太阳能电池对电极La2Mo2O7复合MWCNTs非Pt催化剂的制备与性能

通过高温固相法对醋酸镧（C₆H₉O₆La·xH₂O）与高钼酸铵（（NH₄）₆Mo₇O₂₄·4H₂O）在一定条件下热解制备非Pt催化剂La₂Mo₂O₇（La₂O₃-2MoO₂）。进一步采用2种方法将La₂Mo₂O₇与多壁碳纳米管（MWCNTs）进行复合,一种是将La₂Mo₂O₇喷涂到MWCNTs表层之上得到La₂Mo₂O₇/MWCNTs,另一种是将两者均匀混合掺杂得到La₂Mo₂O₇@MWCNTs,再将上述2种复合材料应用于染料敏化太阳能电池对电极进行相应研究。通过扫描电子显微镜（SEM）表征了复合催化材料的微观形貌,X射线衍射（XRD）确定了微观结构。采用电流密度-光电压曲线、循环伏安,交流阻抗以及塔菲尔极化分析了材料的光电性能。实验结果表明在电解液I₃^-/I^-中,基于La₂Mo₂O₇/MWCNTs与La₂Mo₂O₇@MWCNTs的对电极,相同的条件下在光电池中获得的光电转换效率分别为6.09%和4.84%,明显高于MWCNTs的3.94%和La₂Mo₂O₇的0.87%。电极性能的提高可归因于La₂Mo₂O₇复合催化剂相对大的比表面积和高导电性。     

A Redox‐anchoring Approach to Well‐dispersed MoCx/C Nanocomposite for Efficient Electrocatalytic Hydrogen Evolution

Here we report a redox‐anchoring strategy for synthesizing a non‐noble metal carbide (MoC_x) nanocomposite electrocatalyst for water electrolysis in acidic media, using glucose and ammonium heptamolybdate as carbon and Mo precursors, respectively, without the need of gaseous carbon sources such as CH₄. Specifically, the aldehyde groups of glucose are capable of reducing Mo⁶⁺ to Mo⁴⁺ (MoO₂), and thus molybdenum species can be well anchored by a redox reaction onto a carbon matrix to prevent the aggregation of MoC_x nanoparticles during the following carbonization process. The morphology and chemical composition of the electrocatalysts were well characterized by BSE‐SEM, TEM, XRD and XPS. The obtained MoC_x−2 sample showed a reasonably high hydrogen evolution reaction (HER) activity and excellent stability in an acidic electrolyte, and its overpotential required for a current density output of 20 mA cm⁻² is as low as 193 mV. Such a prominent performance is ascribed to the excellent dispersity and nano‐size, and the large reactive surface area of MoC_x particles. This work may open a new way to the design and fabrication of other non‐noble metal carbide nanocatalysts for various electrochemical applications.     

17O and 183W NMR studies of the paratungstate anions in aqueous solutions

¹⁷O (40.7 MHz) and ¹⁸³W (12.5 MHz) NMR spectra of aqueous Na₁₀[H₂W₁₂O₄₂]·27H₂O (1), Na₆[W₇O₂₄]·14H₂O (2) and (NH₄)₆[Mo₇O₂₄]·nH₂O solutions, as well as of 2, 1 and 0.1 M Na₂WO₄ and 2 M Li₂WO₄ solutions acidified up to P = 0.5, 1 and 1.14 have been measured. The composition of the W₇O₂₄^6? anion remains unchanged (2), its structure being similar to that of Mo₇O₂₄^6?183W NMR spectrum shows three resonances with the chemical shifts + 269.2, ?98.8 and ?178.9 ppm relative to WO₄^2? and intensity ratio 1:4:2. “Paratungstate A” produced during polycondensation of WO₄^2? at P ? 1.17 is identical with heptatungstate W₇O₂₄^6?. The [H₂W₁₂O₄₂]^10?183W NMR spectrum in the acidified 2 M Li₂WO₄ solution has four resonances with the chemical shifts in the range - 105–145 ppm and intensity ratio 1:2:1:2. As suggested by NMR data, the H₂W₁₂O₄₂^10? ? W₇O₂₄^6? transformations occur, which depend upon concentration and temperature.     

Two mixed valent molybdenophosphates with a tunnel structure closely related to K0.17MoP2O7: Pb2(PbO)2Mo8(P2O7)8 and PbK2Mo8(P2O7)8

Two new mixed valent Mo(III)/Mo(IV) diphosphates containing lead Pb₂(PbO)₂Mo₈(P₂O₇)₈ and PbK₂Mo₈(P₂O₇)₈ have been synthesized. The [Mo₈P₁₆O₅₆]∞ frameworks of these phosphates are closely related to that of K_0.17MoP₂O₇: the MoO₆ octahedra and P₂O₇ groups form two sorts of large eight-sided tunnels. They are occupied in an ordered way by PbO chains and Pb²⁺ cations in Pb₂(PbO)₂Mo₈(P₂O₇)₈ and by K⁺ and Pb²⁺ cations in PbK₂Mo₈(P₂O₇)₈. It results in different symmetries of these two structures, which are tetragonal and monoclinic, respectively, showing the great flexibility of these mixed frameworks, susceptible to accommodate various species with different sizes.     

A new lead Mo(IV) phosphate with a tunnel structure: Pb2Mo2O(PO4)2P2O7

A molybdenum (IV) phosphate containing lead, Pb₂Mo₂(PO₄)2P₂O₇, has been synthesized for the first time. It crystallizes in the space group C2/c with a=14.098(1) Å, b=14.187(2) Å, c=6.5592(4) Å and β=102.08(1)°. Its original tunnel structure, built up of Mo₂O₁₁ bioctahedra, P₂O₇ and PO₄ phosphate groups can be described from the assemblage of [Mo₄P₄O₂₄]_∞ ribbons interconnected through monophosphate groups. The stereoactivity of the 6s² lone pair of Pb²⁺, which is surrounded by nine oxygen atoms, is discussed.     

The crystal structure of a complex cerium(III) molybdate containing a dimolybdate chain,Ce2(MoO4)2(Mo2O7)

Ce₂(MoO₄)₂(Mo₂O₇) crystallizes in the triclinic system with unit cell dimensions (from single-crystal data) a = 11.903(8), b = 7.509(5), c = 7.385(5) Å, α = 94.33(8), β = 97.41(8), γ = 88.56(7)°, and space group $\text{P}\text{1}\text{, z = 2}$. The structure was solved using Patterson (“P1 method”) and Fourier techniques. Of the 8065 unique reflections measured by counter techniques, 6314 with I ≥ 3σ(I) were used in the least-squares refinement of the model to a conventional R of 0.035 (R_w = 0.034). The structure of Ce₂(MoO₄)₂(Mo₂O₇) consists of dimolybdate chains of the K₂Mo₂O₇ and (NH₄)₂Mo₂O₇ type separated by isolated MoO₄ tetrahedra and cerium(III) polyhedra.     

Supramolecular Systems Based on Ca2+, [Mo3O2S2Cl6(H2O)3]2s-, [Mo3S4Cl6.75Br0.25(H2O)2]3s- and Cucurbit[6]uril

Adducts of cucurbit[6]uril with Ca²⁺ and trinuclear cluster chloroaquacomplexes (H₉O₄)₂(H₇O₃)₂[(Ca(H₂O)₅)2(C₃₆H₃₆N₂₄O₁₂)]Cl₈·0.67H₂O (1) and [(Ca(H₂O)₅)₂(C₃₆H₃₆N₂₄O₁₂)]× [Mo₃O₂S₂Cl₆(H₂O)₃]₂·13H₂O (2) are obtained and structurally characterized. The structures of both compounds contain polymeric [Ca(H₂O) _n ]₂² CB[6]∞ cations that form infinite columns; the space between them is filled with Cl^s- (1) and [Mo₃O₂S₂Cl₆(H₂O)₃]^2s- (2). A new (H₇O₃)₂(H₅O₂)× [Mo₃S₄Cl_6.25Br_0.25(H₂O)₂](C₃₆H₃₆N₂₄O₁₂)·CH₂Cl₂·6H₂O complex (3) is also obtained and structurally characterized.     

Controlling the Self‐Assembly of a Mixed‐Metal Mo/V–Selenite Family of Polyoxometalates

Five mixed‐metal mixed‐valence Mo/V polyoxoanions, templated by the pyramidal SeO₃^2? heteroanion have been isolated: K₁₀[Mo^VI₁₂V^V₁₀O₅₈(SeO₃)₈]?18 H₂O ( 1 ), K₇[Mo^VI₁₁V^V₅V^IV₂O₅₂(SeO₃)]?31 H₂O ( 2 ), (NH₄)₇K₃[Mo^VI₁₁V^V₅V^IV₂O₅₂(SeO₃)(Mo^V₆V^V‐ O₂₂)]?40 H₂O ( 3 ), (NH₄)₁₉K₃[Mo^VI₂₀V^V₁₂V^IV₄O₉₉(SeO₃)₁₀]?36 H₂O ( 4 ) and [Na₃(H₂O)₅{Mo_18?xV_xO₅₂(SeO₃)} {Mo_9?yV_yO₂₄(SeO₃)₄}] ( 5 ). All five compounds were characterised by single‐crystal X‐ray structure analysis, TGA, UV/Vis and FT‐IR spectroscopy, redox titrations, and elemental and flame atomic absorption spectroscopy (FAAS) analysis. X‐ray studies revealed two novel coordination modes for the selenite anion in compounds 1 and 4 showing η,μ and μ,μ coordination motifs. Compounds 1 and 2 were characterised in solution by using high‐resolution ESI‐MS. The ESI‐MS spectra of these compounds revealed characteristic patterns showing distribution envelopes corresponding to 2? and 3? anionic charge states. Also, the isolation of these compounds shows that it may be possible to direct the self‐assembly process of the mixed‐metal systems by controlling the interplay between the cation “shrink‐wrapping” effect, the non‐conventional geometry of the selenite anion and fine adjustment of the experimental variables. Also a detailed IR spectroscopic analysis unveiled a simple way to identify the type of coordination mode of the selenite anions present in POM‐based architectures.     

Cryoscopic studies in molten salts. Dissociation state of some alkali isopolymolybdates and some related molybdenum(VI) compounds in molten K2Cr2O7and KNO3

The dissociation state of the solutes M₂MoO₄, M₂Mo₃O₁₀, M₂Mo₄O₁₃, M₂Mo₅O₁₆ (MRb or Cs), Na₂CrO₄·MoO₃, K₂CrO₄·2 MoO₃, Cr₂Mo₃O₁₂ and V₂MoO₈ was studied cryoscopically in molten K₂ Cr₂O₇ and KNO₃ solvents. The freezing point depression, ΔT, of the solvents was obtained by measuring the cooling curves of the binary salt mixtures over unlimited range of solute concentration. The number of foreign ions obtained ν, showed that the solutes were either simply dissociated in the melt into the probable stable species (MoO₄)^2?, (Mo₃O₁₀)^2?, (Mo₄O₁₃)^2? and (Mo₅O₁₆)^2? or, in some cases after reactions and rearrangements, into (CrMo₂O₁₀)^2? heteropolyions. The solute V₂MoO₈, on the other hand, was found to dissolve without any apparent dissociation. An agreement between the experimental and calculated values of activity, a, based on the Temkin and Random Mixing models and that of Van't Hoff's equation support the proposed simple dissocia- tion scheme for K₂Cr₂O₇Cs₂MoO₄ system.