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近年来,深共熔溶剂热作为一种绿色合成方法被广泛用于多种杂化功能材料的合成。在本研究中,这一合成方法被引入到多核Zr-和Zr/Ti-O纳米团簇的制备,成功获得被邻菲罗啉、苯酚等共轭配体修饰的Zr6以及Ti11Zr4团簇。此方法将为具有精准结构信息的被较多发色团包覆的纳米团簇的合成开辟新的技术路线。此外,光催化分解水产氢实验结果表明,由于具有不同的簇核环境,这两种纳米团簇表现出不同的分散性及与之相关的产氢活性。因此,该研究也为探索金属氧簇材料的结构–性能关系以及结构设计原则提供了借鉴。 相似文献
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金属纳米团簇(MNCs)是由几个到数百个金属原子组成,其尺寸一般小于2nm.金属纳米团簇在许多催化反应中表现出高的催化活性和选择性,这与金属纳米团簇具有高的比表面积、较多暴露的活性原子,以及与金属纳米粒子(MNPs)不同的电子结构有关.金属纳米团簇确定的组成和结构使其成为一种新型模型催化剂,对纳米团簇的催化性能研究有利... 相似文献
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As opposed to nanoparticles, atomically precise metal clusters possess a well-defined surface and crystal structure, which aids in understanding the relationship between the structure and chemical reactivity at the atomic level. As an interesting subgroup of metal cluster compounds, heterometallic lanthanide-titanium oxo clusters (LnTOCs) have attracted extensive attention due to their interesting chemical properties. However, the controlled precise synthesis of LnTOCs remains a great challenge because of the intense hydrolysis of Ti4+ ions and the competitive coordination of Ln3+ ions. Owing to this synthetic difficulty, high-nuclearity LnTOCs are very rare, which obstructs further studies on their properties. Choosing the appropriate chelating ligands should be an effective strategy to synthesize LnTOCs because chelating ligands can reduce the degree of hydrolysis of Ti4+ ions. Herein, four new LnTOCs, formulated as [EuTi6(μ3-O)3(OC2H5)8(dtbsa)6(Hdtbsa)]·(C2H5OH) (1), [EuTi7(μ3-O)3(μ2-OH)2(OiPr)9(dtbsa)6(Hdtbsa)Cl]·(HOiPr)3 (2), [EuTi7(μ3-O)3(μ2-OH)2(OiPr)8(dtbsa)7(Hdtbsa)]·(HOiPr)3 (3), and [LaTi7(μ3-O)3(μ2-OH)2(OC2H5)8(dtbsa)7(Hdtbsa)]2·(C2H5OH)4 (4), were prepared by a solvothermal method via the reaction of 3, 5-di-tert-butylsalicylic acid (H2dtbsa), rare-earth salts, and Ti(OiPr)4. Single-crystal analysis showed that the heptanuclear compound 1 contains a EuTi6 metal core featuring a trigonal prismatic structure, wherein Eu3+ is located at the center of the prism formed by six Ti4+ ions. The metal core structure of octanuclear compounds 2 and 3 can be viewed as the EuTi6 unit in 1 connected to another Ti4+ on one side of the triangular prism. The metal framework of Ln2Ti14 in 4 can be regarded as a dimer of EuTi7 in 2. UV-Vis diffuse reflectance spectra revealed that the band gaps of 1, 2, and 3 (2.35, 2.07, and 2.16 eV, respectively) are significantly smaller than that of anatase (3.2 eV). The results of photoelectric tests indicated that the three clusters show an obvious photoelectric response, and the charge separation efficiency of 1 and 2 was better than that of 3. In order to explore the applications of these compounds to photocatalysis, H2 production by light-driven water splitting under irradiation by a 300 W Xe lamp (300–800 nm) in an aqueous methanol solution (20 mL, 10%) was attempted. The H2 production rates for 1, 2, and 3 were 112, 106, and 87 μmol∙h-1∙g-1, respectively, which were higher than that obtained with the commercial P25. Powder X-ray diffraction (PXRD) spectra and thermogravimetry (TGA) profiles confirmed the optical and thermal stability of the three clusters. This work not only provides a chelating ligand strategy for the synthesis of LnTOCs but also reveals their light-driven photocatalytic activity stemming from the small band-gap. 相似文献
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光催化技术可以直接将太阳能转化为化学能,制造化学燃料或环境友好的产品。然而,常用的光催化剂大多为具有宽能隙的半导体材料,所需光源大多在紫外区,对太阳光的利用率不高;并且电子-空穴复合率高,导致光催化反应效率低。币金属纳米团簇具有超小尺寸(<2 nm)和分立能级,能够实现电子和空穴的分离,电子结构可调,可以通过调节其电子结构进而提高其光催化性能。同时,精确的原子级组成和结构使其成为一种在原子水平上探索光催化机制的理想模型。本文报道了基于币金属纳米团簇的光催化反应的现状,包括水分解产氢、有机污染物降解和光催化氧化胺等。通过探讨调节币金属纳米团簇的光催化性能的策略,对币金属纳米团簇光催化剂的发展前景予以展望。 相似文献
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以钛-乙二醇配合物纳米棒为模板,结合湿浸渍焙烧法制备了不同长度的钛酸镉(CdTiO3)纳米棒.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、广角X射线粉末衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、热重分析仪(TG)及紫外-可见光谱仪(UV-Vis)等对前驱体及CdTiO3纳米棒进行了表征.结果表明,得到的CdTiO3纳米棒长度分别约为50,20和10μm,且无杂相,晶化度高,尺寸均一.负载1%(质量分数)铂作为助催化剂后,制备的不同长度CdTiO3纳米棒具有比CdTiO3纳米粒子更高的光催化产氢活性.其中,最长的CdTiO3纳米棒具有最高的产氢活性(~52.9μmol/h). 相似文献
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制备了一系列专为超级电容器设计的新型钛氧簇(TOCs,包括Zn-Ti11和Cd-Ti11),扩大了TOCs材料的潜在应用范围。此类材料具有的优异赝电容性能充分展示了钛基材料的优点。所制备的TOCs基超级电容器的最大功率密度为9.5 W·kg-1,能量密度为463 Wh·kg-1。 相似文献
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制备了一系列专为超级电容器设计的新型钛氧簇(TOCs,包括Zn-Ti11和Cd-Ti11),扩大了TOCs材料的潜在应用范围。此类材料具有的优异赝电容性能充分展示了钛基材料的优点。所制备的TOCs基超级电容器的最大功率密度为9.5 W·kg-1,能量密度为463 Wh·kg-1。 相似文献
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通过溶剂热合成方法,以水杨醛肟(H2Saox)和乙酰氧肟酸(H2Ahox)为染料敏化功能配体,分别以异丁酸(HiBuac)和苯基膦酸(PhPO3H2)为辅助配体,与钛酸四异丙酯(Ti (OiPr)4)反应,合成了六核钛氧簇配合物[Ti6(μ3-O)4(Saox)2(iBuac)4(OiPr)8](1)和八核钛氧簇配合物[Ti8(μ3-O)2(Ahox)2(PhPO3)4(OiPr)16](2)。配合物1和2均通过红外光谱、元素分析和单晶X射线衍射进行了结构表征。光谱性质表明,配合物1和2在可见光区均有吸收,其带隙分别为2.43和2.61 eV。配合物2是首个基于乙酰氧肟酸的钛氧簇,具有光催化析氢性能且速率可达140.2 μmol·g-1·h-1。 相似文献
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在本文,采用水热法合成了一种新型的介孔二氧化钛/碳/亚甲蓝复合纳米团簇(TiO2@C-MB),并应用于肿瘤细胞的光动力(PDT)和光热治疗(PTT)。系统中介孔二氧化钛作为有效的光敏剂,MB作为重要的光敏添加剂以改善二氧化钛纳米晶的光化学效应,并将其光响应区域拓宽至光动力学疗法的理想治疗窗(650~900 nm)。柠檬酸在水热条件下被还原成碳并裹覆在二氧化钛表面。碳层表现出良好的光热效果,也充当多功能的电子受体以加速生成单线态氧。该纳米团簇不仅可以保持肿瘤细胞内部高浓度的MB和二氧化钛以产生大量的单线态氧杀死肿瘤细胞,而且可以避免MB退化失活。 相似文献
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A new iron–sulfur cluster compound, namely [(μ‐BNT)Fe2(CO)6] ( A ; BNT = (R)‐1,1′‐binaphthalene‐2,2′‐dithiol), was synthesized by self‐assembly of BNT with [Fe3(CO)12] and characterized using 1H NMR, 13C NMR, infrared spectra and elemental analysis. The H2 evolution activity of A was evaluated in a constructed homogeneous photocatalytic system by combining A as catalyst, xanthene dyes as photosensitizer and triethylamine as sacrificial reagent, to give efficient H2 generation under visible‐light irradiation (λ > 420 nm). The maximum H2 evolution of 404 turnovers (versus catalyst) was recorded under optimal conditions in CH3CN–H2O (1:1, v/v) after 4 h irradiation. The mechanism of H2 evolution is briefly discussed using fluorescence spectra and electrochemical analysis. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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化石燃料的快速消耗加速了全球能源危机和环境污染等问题.光催化产氢直接利用清洁和可持续的太阳能实现向化学燃料的转化,因而成为一种有前景的技术.众多半导体光催化剂中,二氧化钛因其高光催化活性、稳定的化学性质、低成本和无毒等优势而被广泛用作分解水产氢的光催化剂.最近,金红石相TiO2纳米晶体在某些情况下被证明具有光催化的潜力,然而其光生电子-空穴对的快速复合显著抑制了光催化效率.表面修饰、构建异质结和负载助催化剂等策略被用来提高光生载流子的分离效率以减少复合损失,从而提升光催化活性.由于光催化反应通常发生在光催化剂的表面活性位点上,因此通过改善表面性质改变电荷转移途径对光催化活性具有重要影响.磷酸、硫酸、硼酸和盐酸等无机酸的修饰可以改变光催化剂的表面基团,分别通过促进表面羟基的形成和氧气的吸附以及改变表面电荷性质更有效地捕获空穴,实现光生电子和空穴的分离,有助于光催化降解有机污染物.然而,这种影响机制显然不适用于光催化产氢体系,目前对无机酸修饰用于分解水产氢的研究鲜有报道.因此,通过酸改性策略制备高效产氢的光催化剂仍然是一个相当大的挑战.本文利用硝酸诱导策略合成纺锤状金红石相二氧化钛纳米束(R-TiO2).首先,制备层状质子化钛酸盐(LPT)作为TiO2的前体,随后,加入浓硝酸以诱导向金红石相TiO2的转变,并组装形成纺锤状纳米束.对照实验显示,硝酸的酸化可以诱导LPT向金红石相TiO2的转变,而相同条件下浓硝酸后处理不会引起晶相的转变.纺锤形纳米束的形成源于,硝酸诱导R-TiO2沿(110)方向生长并彼此粘附,硝酸诱导组装过程成功在TiO2表面修饰上硝酸根,同时扩大了光吸收范围,有效减少了电荷复合损失.光催化产氢测试证明了R-TiO2光催化剂具有高效的产氢性能,产氢速率为402.4μmol h-1,是Degussa P25的3.1倍,并且显著高于未经浓硝酸处理的锐钛矿(52.0μmol h^-1)或金红石相(110.8μmol h^-1)光催化剂.为了说明表面硝酸根的影响,分别从晶体和化学结构、形态以及表面电荷性质方面比较了光催化反应前后的变化,结果表明,R-TiO2增强的光催化效率可归因于硝酸根基团的负场效应,有利于在表面上捕获带正电的质子以促进载流子分离,提高光催化产氢的效率.总之,本工作不仅对于发展表面修饰策略制备高效产氢光催化剂的研究具有重要意义,而且提出了一种不同于文献报道的无机酸影响机制. 相似文献
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Zhang Z Lin Q Zheng ST Bu X Feng P 《Chemical communications (Cambridge, England)》2011,47(13):3918-3920
A tin(II) tungstosilicate derivative K(11)H[Sn(4)(SiW(9)O(34))(2)]·25H(2)O with four sandwiched Sn(2+) cations was prepared by reaction of SnCl(2), KCl and Na(10)[α-SiW(9)O(34)]·xH(2)O. Visible-light photocatalytic H(2) evolution activity was observed with Pt nanoparticles as co-catalyst and methanol as sacrificial agent. 相似文献
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Electro‐oxidation and reduction of H2 on platinum studied by scanning electrochemical microscopy for the purpose of local detection of H2 evolution
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Sina S. Jamali Simon E. Moulton Dennis E. Tallman Jan Weber Gordon G. Wallace 《Surface and interface analysis : SIA》2015,47(13):1187-1191
Electrochemical detection of H2 using scanning electrochemical microscopy (SECM) has shown to hold great promise as a sensitive characterization method with high spatial resolution for active surfaces generating H2. Herein, the factors contributing to the current that is measured by SECM in generation/collection mode for H2 detection are studied. In particular, the concentration gradient of H2 at the substrate, the H2/H+ recycling between the SECM tip and substrate and hemispherical profile of H2 diffusion has been discussed. It was postulated that H2/H+ recycling plays a dominant role in the oxidative current measured in generation/collection mode of SECM when the microelectrode is positioned in close vicinity of substrate. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Xiao Liu Peijie Fan Liangping Xiao Jian Weng Qingchi Xu Jun Xu 《Journal of Energy Chemistry》2021,(2):185-191,I0007
The generation of green hydrogen(H_2) energy is of great significance to solve worldwide energy and environmental issues. Reduced Ti based photocatalyst has recently attracted intensive attention due to its excellent photocatalytic activity, while the synthesis of reduced Ti based photocatalysts with high stability is still a great challenge. Here, we report a facile method for synthesis of reduced Ti metal organic frameworks(small amounts of Pt incorporated) encapsulated BP(BP/R-Ti-MOFs/Pt) hybrid nanomaterial with enhanced photocatalytic activity. The strong interaction between Ti and P reduces the valence state of the binding Ti4+on the BP surface, forming abundant reduced Ti4+within R-Ti-MOFs/BP. Such reduced Ti4+render R-Ti-MOFs/BP efficient charge transfer and excellent light absorption capability, thus promote the photocatalytic H_2 production efficiency. Furthermore, the Ti-P interaction stabilizes both reduced Ti4+and BP during the photocatalytic reaction, which greatly enhanced the stability of the obtained BP/R-TiMOFs/Pt photocatalyst. 相似文献
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Photocatalytic hydrogen production from water splitting is of promising potential to resolve the energy shortage and environmental concerns. During the past decade, carbon materials have shown great ability to enhance the photocatalytic hydrogen-production performance of semiconductor photocatalysts. This review provides a comprehensive overview of carbon materials such as CNTs, graphene, C60, carbon quantum dots, carbon fibers, activated carbon, carbon black, etc. in enhancing the performance of semiconductor photocatalysts for H2 production from photocatalytic water splitting. The roles of carbon materials including supporting material, increasing adsorption and active sites, electron acceptor and transport channel, cocatalyst, photosensitization, photocatalyst, band gap narrowing effect are explicated in detail. Also, strategies for improving the photocatalytic hydrogen-production efficiency of carbon-based photocatalytic materials are discussed in terms of surface chemical functionalization of the carbon materials, doping effect of the carbon materials and interface engineering between semiconductors and carbon materials. Finally, the concluding remarks and the current challenges are highlighted with some perspectives for the future development of carbon-based photocatalytic materials. 相似文献