电解液流速对锌镍单液流电池性能的影响

通过电化学测试、 扫描电子显微镜观察和X射线衍射分析研究了电解液流速、 电流密度和锌沉积面容量三者关系及对锌镍单液流电池充放电性能和负极锌沉积形貌的影响. 结果表明, 锌沉积面容量是影响锌镍单液流电池充放电效率和负极锌沉积形貌的最主要因素, 电解液流速不宜过高或过低. 随着锌沉积面容量的增大, 电池的充放电效率和循环稳定性对电流密度的变化更为敏感, 适宜的电解液流速范围变窄. 锌沉积面容量在25 mA·h/cm²以上, 锌沉积皆呈海绵状. 在较低锌沉积面容量下, 电解液流速也较低时, 海绵锌沉积较为均匀致密. 而在高的锌沉积面容量下, 海绵状锌沉积的团簇和颗粒变大, 不均匀性加重, 仅在适中的电解液流速(7.1 L/min)下, 锌沉积部分致密规整, 电池具有较好的充放电性能.     

6-甲氧羰基-4,4'-二甲基-2,2'-联吡啶单核铜(Ⅰ)双膦发光配合物

合成并表征了2个新的基于6-甲氧羰基-4,4''-二甲基-2,2''-联吡啶的单核铜（Ⅰ）双膦配合物[Cu（mmbpy）（dppp）]ClO₄（1）和[Cu（mmbpy）（dppb）]ClO₄（2）。研究结果表明,铜（Ⅰ）配合物1和2均表现为扭曲变形的N₂P₂四面体几何构型,其P-Cu-P键角受辅助双膦配体控制。在常温下,这2个铜（Ⅰ）配合物在固态时均具有发光性质,并且相对于双膦配体亚甲基链的长度,P-Cu-P键角对其光物理性质的影响更为显著。在2,2''-联吡啶环上引入2个甲基取代基对改善铜（Ⅰ）配合物的发光性能也被证明是有效的。     

SnS2/GCP(石墨烯复合粉末)微米复合材料作为锂离子电池负极材料的电化学性能

以石墨烯复合粉末为添加剂,采用一步水热法制备了一种SnS₂/GCP微米复合材料。在所得到的复合材料中,SnS₂纳米片相互缠绕组成多孔球状SnS₂颗粒,石墨烯复合粉末均匀的包裹在球状SnS₂颗粒表面。将所制备的SnS₂/GCP微米复合材料用作锂离子电池负极材料测其电化学性能。结果显示,在0.1 A·g^-1的电流密度下可逆比容量为795.6 mAh·g^-1,循环100次后比容量损失不到1%。相比于SnS₂其比容量和循环稳定性得到了明显改善,主要是由于石墨烯复合粉末的加入,不仅缓解了SnS₂颗粒在充放电过程中的团聚和体积膨胀,而且还提高了SnS₂颗粒的电导率。     

基于4-氨基-1,2,4-三唑和多金属氧酸盐为杂化配体的CuⅡ和CuⅠ配合物的水热合成及光催化性能

在水热条件下,制备了2个基于多金属氧酸盐（POM）的Cu^Ⅱ和Cu^Ⅰ新型杂化配合物材料,即[Cu₂（4-NH₂-trz）₄（Mo₈O₂₆）（H₂O）₄]·5H₂O（1）和[Cu₄（4-NH₂-trz）₄Mo₈O₂₆]（2）（4-NH₂-trz=4-氨基-1,2,4-三唑）。通过单晶X射线衍射、傅里叶变换红外光谱和粉末X射线衍射分析确定了它们的结构。在配合物1中,4-氨基-1,2,4-三唑双齿配体连接2个相邻的Cu^Ⅱ中心形成双核结构单元,这些双核结构单元进一步通过Mo₈O₂₆^4-连接形成一维（1D）的杂化配位结构。在配合物2中,4-氨基-1,2,4-三唑双齿配体连接相邻Cu^Ⅰ中心构筑了独特的[Cu₄（4-NH₂-trz）₄]_n一维螺旋链,这些左手和右手的一维螺旋链再通过（β-Mo₈O₂₆）^4-连接形成2D杂化骨架。光催化实验研究表明,样品1和样品2对于不同有机染料（亚甲基蓝（MB）、罗丹明B（RhB）和甲基橙（MO））具有很好的光催化降解能力。     

新型BiOI/g-C3N4纳米片复合光催化剂的制备及其可见光催化活性增强

近年来, 石墨型氮化碳(g-C3N4)作为一种n型半导体光催化剂材料, 由于具有较好的热稳定性和化学稳定性, 同时具有可调的带隙结构和优异的表面性质而备受人们关注. 然而, 传统的g-C3N4块体材料存在比表面积小、光响应范围窄和光生载流子易复合等缺陷, 制约着其光催化活性的进一步提高. 因此, 人们开发了多种技术对块体状g-C3N4材料进行改性,其中构建基于g-C3N4纳米薄片的异质结复合光催化材料被认为是强化g-C3N4载流子分离效率, 进而提高其可见光催化活性的重要手段. BiOI作为一种窄带隙的p型半导体光催化剂, 具有强的可见光吸收能力和较高的光催化活性, 同时它与g-C3N4纳米薄片具有能级匹配的带隙结构. 因此, 基于以上两种半导体材料的特性, 构建新型的BiOI/g-C3N4纳米片复合光催化剂材料不仅能够有效提高g-C3N4的可见光利用率, 而且还可以在n型g-C3N4和p型BiOI界面间形成内建电场, 极大促进光生电子-空穴对的分离与迁移效率.为此, 本文通过简单的一步溶剂热法在g-C3N4纳米薄片表面原位生长BiOI纳米片材料, 成功制备了新型的BiOI/g-C3N4纳米片复合光催化剂. 利用X射线衍射仪(XRD), 场发射扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见漫反射光谱和瞬态光电流响应谱对所合成复合光催化剂的晶体结构、微观形貌、光吸收性能和电荷分离性能进行了表征测试. XRD, SEM和TEM结果显示, 结晶完好的BiOI呈小片状均匀分散在g-C3N4纳米薄片表面; 紫外漫反射光谱表明, 纳米片复合材料的吸光性能较g-C3N4薄片有显著提升; 瞬态光电流测试证明, 复合材料较单一材料有更好的电荷分离与迁移性能.在可见光催化降解RhB的测试中, BiOI/g-C3N4纳米片复合光催化剂显示出了优异的催化活性和稳定性, 其光降解活性分别为纯BiOI和g-C3N4的34.89和1.72倍; 自由基捕获实验发现, 反应过程中的主要活性物种为超氧自由基(·O2-), 即光生电子主导整个降解反应的发生. 由此可见, 强的可见光吸收能力和g-C3N4与BiOI界面处形成的内建电场协同促进了g-C3N4纳米薄片的电荷分离, 进而显著提高了该复合材料的可见光催化降解活性. 此外, 本文初步验证了在BiOI/g-C3N4纳米片复合光催化体系内光生电荷是依据"双向转移"机制进行分离和迁移的, 而非"Z型转移"机制.     

密度泛函理论计算研究表面应力对钯催化乙炔选择性加氢活性与选择性的影响（英文）

在石油催化裂解过程中,除了生成乙烯、丙烯及丁烯等烯烃,还会产生部分炔烃.目前工业上通常采用炔烃选择性加氢转化为对应的单烯烃,以除去其中炔烃.由于产品烯烃中的炔烃等杂质含量需极低,这就对用于加氢催化剂的活性和选择性提出了很高的要求,即催化剂需要选择性吸附炔烃并加氢,而不损失其中的烯烃.经过前期大量的基础研究工作,目前工业中炔烃选择性加氢应用最广泛的催化剂是负载型钯基催化剂.然而,单独的钯金属选择性并不理想,因而对其选择性以及活性进行调控成为了当前关注的研究课题.本文采用密度泛函理论计算结合微观反应动力学模拟手段,研究了钯金属表面应力存在条件下的活性与选择性,以及形成次表层物种的可能性和形成后的活性与选择性.研究发现,改变钯金属的晶格参数与表面应力,反应物、表面反应中间体和产物的吸附能都会产生相应的变化,且吸附能与晶格参数的变化存在线性关系,晶格参数越大,吸附越强.利用表面反应过渡态能量与初始态能量之间的线性关系,相应的乙炔加氢生成乙烯的反应速率可以通过微观反应动力学模拟得到.结果显示,不同晶格参数的钯催化剂催化乙炔加氢生成乙烯的反应活性位于相应火山型曲线的强吸附侧,即减弱乙炔和氢的吸附强度可提高乙烯的生成速率.在此基础上,本文研究了不同表面应力的钯催化剂在次表面吸附不同覆盖度碳原子和氢原子的情况,发现晶格参数越大越有利于碳原子和氢原子在次表面的吸附.同时,研究发现在次表面碳掺杂的条件下,不同表面应力条件下的钯催化剂的活性均有所增强.此外,由于乙烯在所有研究的钯催化剂表面脱附比进一步加氢容易,因而乙烯都可以选择性生成.     

Microwave-hydrothermal synthesis and photocatalytic properties of biomass charcoal/TiO2 nanocomposites

Biomass charcoal-doped titanium dioxide (C/TiO₂) composites were proposed by microwave-hydrothermal and calcination method using tetrabutyl titanate as the titanium source and lignin as the carbon source. TiO₂ crystals with different morphologies could be successfully adsorbed onto the surface of biomass charcoal. These products were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), derivative thermogravimetric (DTG), UV–vis diffuser flection spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FT-IR), and Brunauer–Emmett–Teller (BET). The photocatalytic activities of the as-obtained composites were checked under visible light irradiation. The results showed that both the microwave-hydrothermal temperature and time played an important role in the microstructure and photocatalytic activity of the samples. The rapid microwave-hydrothermal with the thermal post-treatment provides a promising route for the fabrication of biomass charcoal-doped nanocomposites materials.     

Enhanced Photodynamic Therapy by Reduced Levels of Intracellular Glutathione Obtained By Employing a Nano‐MOF with CuII as the Active Center

In photodynamic therapy (PDT), the level of reactive oxygen species (ROS) produced in the cell directly determines the therapeutic effect. Improvement in ROS concentration can be realized by reducing the glutathione (GSH) level or increasing the amount of photosensitizer. However, excessive amounts photosensitizer may cause side effects. Therefore, the development of photosensitizers that reduce GSH levels through synergistically improving ROS concentration in order to strengthen the efficacy of PDT for tumor is important. We report a nano‐metal–organic framework (Cu^II‐metalated nano‐MOF {CuL‐[AlOH]₂}_n (MOF‐2, H₆L=mesotetrakis(4‐carboxylphenyl)porphyrin)) based on Cu^II as the active center for PDT. This MOF‐2 is readily taken up by breast cancer cells, and high levels of ROS are generated under light irradiation. Meanwhile, intracellular GSH is considerably decreased owing to absorption on MOF‐2; this synergistically increases ROS concentration and accelerates apoptosis, thereby enhancing the effect of PDT. Notably, based on the direct adsorption of GSH, MOF‐2 showed a comparable effect with the commercial antitumor drug camptothecin in a mouse breast cancer model. This work provides strong evidence for MOF‐2 as a promising new PDT candidate and anticancer drug.     

Mechanofluorochromic Carbon Nanodots: Controllable Pressure‐Triggered Blue‐ and Red‐Shifted Photoluminescence

Mechanofluorochromic materials, which change their photoluminescence (PL) colors in responding to mechanical stimuli, can be used as mechanosensors, security papers, and photoelectronic devices. However, traditional mechanofluorochromic materials can only be adjusted to a monotone direction upon the external stimuli. Controllable pressure‐triggered blue‐ and red‐shifted PL is reported for C‐dots. The origin of mechanofluorochromism (MFC) in C‐dots is interpreted based on structure–property relationships. The carbonyl group and the π‐conjugated system play key roles in the PL change of C‐dots under high pressure. As the pressure increases, the enhanced π–π stacking of the π‐conjugated system causes the red‐shift of PL, while the conversion of carbonyl groups eventually induces a blue‐shift. Together with their low toxicity, good hydrophilicity, and small size, the tunable MFC property would boost various potential applications of C‐dots.     

Structural diversity of isothiocyanato Cd(II) and Zn(II) Girard’s T hydrazone complexes in solution and solid state: effect of H-bonding on coordination number and supramolecular assembly of Cd(II) complex in solid state

The isothiocyanato Zn(II) complex (1) and mixed isothiocyanato/thiocyanato Cd(II) complex (2) with the condensation product of 2-acetylpyridine and trimethylammoniumacetohydrazide chloride (Girard’s T reagent) (HLCl) were investigated both experimentally and theoretically. The crystal structures of both complexes showed tridentate N₂O coordination of hydrazine ligand. In complex 1 square-pyramidal coordination surrounding of Zn(II) consists of deprotonated hydrazone ligand and two isothiocyanato ligands, while in octahedral Cd(II) complex ligand is coordinated without deprotonation as a positively charged species and coordination geometry is completed with two N-coordinated and one S-coordinated NCS^? anions. NMR spectroscopy and molar conductivity results for Cd(II) and Zn(II) complexes indicated their instability in solution. DFT calculations were performed to explain coordination preference and stability of complexes 1 and 2 in solid state and in solution. The obtained Cd(II) complex is the first reported mononuclear pseudohalide/halide Cd(II) complex with quinoline-/pyridine-based hydrazone ligands possessing octahedral geometry in solid state. In this complex, H-bonding has significant impact on coordination number and supramolecular assembly in solid state.