High electrochemical performance of metal azolate framework-derived ZnO/Co3O4 for supercapacitors

Metal azolate frameworks MAF-6 (Zn, Zn Co, and Co) were fabricated with a facile solution mixture method. Flower-like ZnO/Co₃O₄ was synthesized with MAF-6 as the template in a solvothermal condition of 90°C for 2 hours. The produced materials were characterized by XRD, EDS, SEM, and XPS. MAF-6 and the derived metal oxides acted as the electrode materials of supercapacitors. This study reported that ZnO/Co₃O₄ exhibited the maximal specific capacitance of 830.20 F/g at 1A/g, resulting from the synergy of Zn and Co and the enhanced conductivity. Furthermore, ZnO/Co₃O₄ electrode exhibited prominent rate capacitance, high electrochemical reversibility, and long life (89% capacitance was kept after 1000 cycles at 1 A/g). Given the results of this study, the prepared ZnO/Co₃O₄ electrode can be demonstrated as a potential candidate in the field of renewable energy storage.     

Theoretical studies on cyclometalated platinum(II) complexes based on isoquinolinyl azolate: ππ-stacking interaction and photophysical properties

The photophysical properties of four Pt(II) complexes [Pt(Lx)₂], x = 1–4, (1–4), where Lx are 6-t-butyl-1-(3-trifluoro-methyl-1H-pyrazol-5-yl) isoquinoline (1), 3,5-di-t-butyl-1-(3-trifluoromethyl-1H-pyrazol-5-yl) isoquinoline (2), 6-(2,6-diisopropylphenyl)-1-(3-trifluoro-methyl-1H-pyrazol-5-yl) isoquinoline (3), and 4-(2,6-diisopropylphenyl)-1-(3-trifluoro-methyl-1H-pyrazol-5-yl) isoquinoline (4), are investigated by the density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Furthermore, the binding interaction in Pt_n stack is studied to discover the influence of different cyclometalated ligand. The calculated results rationalize that the complex 1 exhibits a stack of three molecules rather than the infinite aligned stack. Complexes 1 and 3 present the stronger tendency to form the aligned ππ-stacking interaction as compared with complexes 2 and 4. The dimers of other four complexes, 3a (Pt(L3)(Ma), Ma = 5-(2-pyridyl)-3-trifluoromethylpyrazole), 3b (Pt(L3)(Mb), Mb = 5-(4-phenyl-2-pyridyl)-3-trifluoromethylpyrazole), 3c (Pt(L3)(Mc), Mc = 5-(4-tert-butyl-2-pyridyl)-3-trifluoromethylpyrazole), and 5 (Pt(fppz)₂ fppz = 5-(2-pyridyl)-3-trifluoromethylpyrazole), are also studied to investigate the effect of different aromatic ligand or substituents on the ππ-stacking interaction. The emissions of complexes 1–4 originate from various charge transfer states including the intraligand charge transfer (ILCT) and ligand-to-ligand charge transfer (LLCT) together with the metal-to-ligand charge transfer (MLCT). Finally, the items related with the radiative and nonradiative rate constants are examined. Besides the potential energy profile between the lowest triplet state (³MLCT) and metal centered state (³MC), the deactivation process of the ³MC state via the minimum energy crossing point (MECP) between the ³MC and the ground state (¹S₀) potential surfaces is also explored.     

金属多氮唑骨架材料(MAF-6)作为棉籽油添加剂的摩擦学性能

采用模板剂法合成金属多氮唑骨架材料(MAF-6),通过SRV-V高频线性往复摩擦磨损试验机研究其作为润滑油固体添加剂的摩擦学性能。利用3D白光干涉仪、扫描电子显微镜(SEM)、X射线能谱分析(EDS)等表征手段分析磨损表面形貌及元素分布,探讨MAF-6的润滑机制。结果表明:MAF-6作为添加剂能有效提高棉籽油的抗磨性能,MAF-6质量分数为0.50%时油品表现出最佳的抗磨性能;在高往复频率和运行载荷下MAF-6的抗磨效果更显著,在最佳添加量下可使基础油抗磨性能提升30%以上。磨损表面EDS元素分析发现,MAF-6的特征元素转移到了摩擦副表面,这表明MAF-6良好的抗磨性能主要与其柔性晶体结构和在摩擦副表面形成的物理吸附膜有关。