Energy Band Alignment and Redox-Active Sites in Metalloporphyrin-Spaced Metal-Catechol Frameworks for Enhanced CO2 Photoreduction

Two new chemically stable metalloporphyrin-bridged metal-catechol frameworks, InTCP-Co and FeTCP-Co, were constructed to achieve artificial photosynthesis without additional sacrificial agents and photosensitizers. The CO₂ photoreduction rate over FeTCP-Co considerably exceeds that obtained over InTCP-Co, and the incorporation of uncoordinated hydroxyl groups, associated with catechol, into the network further promotes the photocatalytic activity. The iron-oxo coordination chain assists energy band alignment and provides a redox-active site, and the uncoordinated hydroxyl group contributes to the visible-light absorptance, charge-carrier transfer, and CO₂-scaffold affinity. With a formic acid selectivity of 97.8 %, FeTCP-OH-Co affords CO₂ photoconversion with a reaction rate 4.3 and 15.7 times higher than those of FeTCP- Co and InTCP-Co, respectively. These findings are also consistent with the spectroscopic study and DFT calculation.     

(Yb3+, Mn2+) Co-doped CdTe nanocrystals with enhanced quantum yields and red-shift emission

We prepared the nanocrystals (NCs) of CdTe, CdTe:Yb, and CdTe:Yb, Mn vis water phase synthesis and examined their structural, morphological, and optical properties. All NCs have a particle diameter of about 2–4 nm, and the monodispersed, uniform spherical, cubic structure of the CdTe NC remains largely unchanged after the doping with Yb and Mn. According to the X-ray diffraction results, the CdTe, CdTe:Yb, and CdTe:Yb, Mn NCs all have a cubic structure, and the diffraction peak of CdTe:Yb NC is at a lower 2θ angle compared with that of the CdTe NC. With the CdTe NC as the reference, the UV–Vis absorption of the CdTe:Yb and the CdTe:Yb, Mn NCs exhibits a blueshift and a redshift, and the emission of CdTe:Yb and CdTe:Yb, Mn has a blueshift of about 12 nm and a redshift of about 73 nm, respectively. The CdTe:Yb, Mn NCs have higher quantum yields than the CdTe:Yb NC, and the quantum yield is the highest when CdTe is doped with 1:1 Mn²⁺/Yb³⁺. In addition, both the CdTe:Yb and CdTe:Yb, Mn NCs have a shorter fluorescence lifetime than the CdTe NC.     

The Shackling Effect in Cyclic Azobenzene Liquid Crystal

We demonstrate here a novel method for the design of liquid crystals (LCs) via the cyclization of mesogens by flexible chains. For two azobenzene-4,4′-dicarboxylate derivatives, the cyclic dimer, cyclic bis(tetraethylene glycol azobenzene-4,4′-dicarboxylate) (CBTAD), shows LC properties with smectic A phase, while its linear counterpart, bis(2-(2′-hydroxyethyloxy)ethyl azobenzene-4,4′-dicarboxylate (BHAD), has no LC phase. The difference is ascribed to the shackling effect from the cyclic topology, which leads to the much smaller entropy change during phase transitions and increases the isotropic temperature greatly for cyclics. In addition, the trans-to-cis isomerization of azobenzene groups under UV-light is also limited in CBTAD. With the reversible isomerization of azobenzene groups, CBTAD showed interesting isothermal phase transition behaviors, where the LC phase disappeared upon photoirradiation of 365 nm UV-light, and recovered when the UV-light was off. Combined with the smectic LC nature, a novel UV-light tuned visible light regulator was designed, by simply placing CBTAD in two glass plates. The scattered phase of smectic LC was utilized as the “OFF” state for light passage, while the UV-light induced isotropic phase was utilized as the “ON” state. The shackling effect outlined here should be applicable for the design of cyclic LC oligomers/polymers with special properties.

     

ZIF-67/石墨烯复合物衍生的氮掺杂碳限域Co纳米颗粒用于高效电催化氧还原

燃料电池阴极氧还原(ORR)催化剂目前主要以商业Pt/C为主, 其高成本和稀缺性极大地限制了燃料电池的广泛应用. 为了替代Pt/C催化剂, 廉价高效的非贵金属催化剂目前受到了广泛的研究和关注. 利用氧化石墨烯(GO)为诱导模板, 借助表面丰富的含氧官能团, 实现了Co基金属有机框架材料(MOF) (ZIF-67)在GO表面的原位生长, 构筑了ZIF-67/GO层状复合材料. 热解过程中, 石墨烯的存在有效抑制了Co纳米颗粒的团聚, 并且很好地维持了原始的层状结构. 最终获得的Co@N-C/rGO复合催化剂材料实现了活性位的高度分散, 并且具有丰富的孔结构和优异的导电性能. 在电化学性能测试中Co@N-C/rGO表现出优异的ORR性能, 其起始电位为0.96 V, 半波电位0.83 V, 远优于ZIF-67直接热解得到的Co@N-C材料, 且性能与商业Pt/C催化剂相当. 此外, Co@N-C/rGO复合催化剂还表现出良好的催化稳定性和甲醇耐受性, 显示出该材料作为燃料电池氧还原催化剂的重要潜力.     

单取代芳烃对位选择性碳氢活化反应研究

以单取代芳烃为芳基化试剂,以羰基为导向定位基团,研究了单取代芳烃对位选择性与芳香酮的交叉脱氢偶联反应。该方法的高选择性一方面体现在用作芳基化试剂的单取代芳烃能够单一选择性地发生对位碳氢活化,并生成对位取代产物;另一方面,作为弱导向基团的羰基具有优异的邻位导向定位作用,高选择性地发生羰基邻位碳氢键活化。此外,该方法还具有反应条件温和、反应效率高、底物范围广、氧化剂廉价易得等优点,为对位取代联芳基化合物的合成提供了一条切实可行的途径。     

船舶水下减阻抗污涂层的研究综述

船舶由于在航行时受到各种阻力,消耗了大量能量,增加了航行成本。船舶水下阻力的来源可以大致分为船体阻力和生物质附加阻力。本文基于对阻力和生物质黏附形成过程的分析,介绍了水下减阻领域的进展突破,总结了具有减阻、抗污性质的涂层研究情况,从超疏水、超亲水减阻材料和自抛光防污涂料、低表面能抗黏附材料、防污剂等方面,对其中相关的科学问题和解决方法进行了综述。     

Characterization and properties of plywood bioadhesive derived from cottonseed protein and sawdust cellulose

Cellulose - The development of plant adhesive with good bonding strength, water resistance and thermal stability remains challenging to replace formaldehyde-based adhesive resins that usually...     

PtRuAgCoNi高熵合金纳米颗粒高效电催化氧化5-羟甲基糠醛

5-羟甲基糠醛(HMF)的电催化氧化被认为是合成2,5-呋喃二甲酸(FDCA)最环保、经济和有效的方法之一,它可作为聚呋喃二甲酸乙二醇酯(PEF)的生物基前体。在这项工作中,我们通过低温溶剂热法合成了PtRuAgCoNi高熵合金纳米颗粒,并在不改变颗粒结构和组成的情况下进行了简易的处理以去除表面活性剂。负载在碳载体上的合金纳米催化剂无论是否含有表面活性剂在HMF电催化氧化为FDCA的过程中都表现出比商业Pt/C更好的催化性能。且表面活性剂的去除可以进一步提高其电催化性能,表明高熵合金纳米粒子在电催化和绿色化学中具有广阔的应用前景。     

“三维”立体化保障体系为化学学科教书育人做好核心支撑——吉林大学化学学院人才培养保障工作实践探索

目前,我国高等教育发展已经进入“深水区”和“无人区”,校、院层面围绕人才培养建立的管理机制、服务机制需要广大教育工作者的探索与实践。吉林大学化学学院充分利用职称评聘、教师能力发展、学生活动、教学改革和课程建设等方面的政策导向,健全奖励激励制度,加强配套经费支持,探索构筑了以教师和学生为主体,涉及教学、管理和服务的“三维”立体化保障体系,有效地促进和保障了学院高质量拔尖创新人才培养。