二维MXene材料——Ti_3C_2T_x在钠离子电池中的研究进展

作为第一个被制备出来的MXene材料,Ti_3C_2T_x独特的二维层状结构使其具有良好的电学、光学、力学与热电等性质,在电化学储能领域展现出巨大的潜力。由于钠储量在地球中较为丰富且远高于锂储量,因此钠离子电池具有成本低等优点,成为近几年储能领域的研究热点。主要围绕Ti_3C_2T_x的特性,介绍了其通过插层、造孔等改性方法以及与单质、金属氧化物、金属硫化物结合构成复合材料作为钠离子电池电极材料的研究进展。最后指出应采取基于钠离子脱嵌或反应的更有针对性的优化方法提升总体的电化学性能。     

Ti3C2MXene纳米片制备、改性及其光催化应用研究

近年来,利用光催化缓解环境污染和能源短缺问题受到广泛关注。Ti₃C₂MXene作为一种新型二维材料,具有丰富的表面基团、多活性位点以及优异的光热和导电性能,在光催化应用研究上逐渐深入。本文概述了Ti₃C₂MXene纳米片的结构、光电特性及合成方法,讨论了二维Ti₃C₂纳米片及其改性材料的复合结构,重点分析了Ti₃C₂纳米片在新型有机污染物降解、水分解产氢和CO₂还原的光催化应用研究进展,对Ti₃C₂纳米片的深入研究提供一定的参考价值。     

Ti3C2TxMXene光催化应用研究进展

新型环境友好材料的开发是解决能源短缺和环境污染问题的关键。自2011年MXenes被合成以来,独特的二维层状结构、良好的导电性以及丰富的表面官能团使其受到了密切的关注,并被广泛地应用于光催化能源转换、环境污染治理等领域。在众多的MXenes中,Ti₃C₂T_xMXene是最早被报道的也是目前研究最多的材料。研究发现Ti₃C₂T_xMXene在光催化体系中能够促进光生电子-空穴的分离、减少电荷复合,从而提高该体系的光催化性能,其在光催化领域显示出了巨大的潜力。概述了MXenes材料的结构特性,重点介绍了Ti₃C₂T_xMXene材料在光催化析氢、光催化降解污染物、CO2的光催化还原以及光催化固氮方面的应用进展。最后,总结并讨论了Ti₃C₂T_xMXene材料在光催化应用领域面临的三大挑战。     

寡层Ti3C2Tx改性锂硫电池隔膜的研究

利用氟化锂和盐酸对前驱体Ti₃AlC₂进行刻蚀,成功得到寡层Ti₃C₂T_x纳米片,通过真空抽滤将其负载至商用锂硫电池PE隔膜上,得到修饰层厚度约为710 nm的层状选择性透过Ti₃C₂T_x材料修饰PE隔膜。通过层间距筛分多硫化物和锂离子,该复合隔膜能够有效阻挡多硫化物的穿过,但不影响锂离子的传输。实验结果表明,选择性透过隔膜的锂硫电池具有优异的循环性能,在1 C倍率下,其初始比容量为750.3 mA·h/g,循环200圈后比容量仍然有481.3 mA·h/g,容量保持率高达64.15%。     

MXene的制备与应用

近年来,二维材料因具有独特的性质受到人们的广泛关注。新型二维材料MXene,具有优异的导电性、比电容、比表面积,更重要的是表面存在一些特征官能团,使其在超级电容器、催化、吸附、气体传感器和复合材料等领域中得到越来越广泛的应用。本文着重阐释了MXene中最具代表的Ti₃C₂的制备方法：氢氟酸蚀刻、盐酸和氟化盐混合溶液蚀刻、熔融盐蚀刻,以及它们在吸波材料、储能材料、吸附材料等领域的应用。     

MXene@CS复合絮凝剂的制备及其对刚果红去除的研究

壳聚糖（CS）因具有大量的羟基和氨基,可为吸附色素污染物提供较多活性位点,但其在酸性条件易于溶解。MXene可为CS提供支撑位点,从而构建新型MXene@CS复合材料。研究构建了新型Ti₃C₂T_X@CS有机无机复合材料,并应用于刚果红的去除研究。通过对Ti₃C₂T_X@CS的微观形貌、晶体结构、表面官能团等进行表征分析,发现Ti₃C₂T_X@CS的复合过程为物理复合。絮凝实验结果表明：在Ti₃C₂T_X@CS投加量为30 mg、溶液pH为9、反应时间为30 min、温度为25~60 ℃条件下,Ti₃C₂T_X@CS对50 mL质量浓度为500 mg/L刚果红（CR）溶液的脱色率达到99%以上。通过实验结果和反应前后Ti₃C₂T_X@CS电位变化推断,Ti₃C₂T_X@CS对刚果红的去除机理主要是电中和作用和吸附架桥作用。     

五氟乙氧基环三磷腈添加剂对钠离子电池性能的影响

储量丰富的钠使钠离子电池在大规模储能领域得到广泛应用,但是钠离子电池的循环性能还需进一步改善。在1 mol/L NaClO₄/EC/PC电解液中加入0. 5%五氟乙氧基环三磷腈(FPN)添加剂,可以有效地调控P2-Na_xCo_{0. 7}Mn_{0. 3}O₂(x≈1. 0)钠离子正极材料的界面稳定性,提高钠离子电池的循环稳定性。电化学和物化表征分析测试结果表明,FPN添加剂的加入可以在P2-Na_xCo_{0. 7}Mn_{0. 3}O₂(x≈1. 0)正极材料表面形成一层富含Na F的致密正极电解质中间相(CEI),该CEI层可以明显降低电池的阻抗,抑制电解液的持续分解,使得电池在1 C倍率下循环200圈之后还可以保持92%的容量保持率,而没有添加FPN添加剂的基础电解液在1 C倍率下循环200圈之后的容量保持率只有75%。     

Ti3C2Tx–Mg Fe2O4复合材料的制备及氨气气敏性能

开发一种性能优异的氨气气体传感器对人类健康和环境保护具有重要意义。利用溶胶凝胶法制备了MgFe₂O₄纳米材料,并通过乙醇超声分散法与Ti₃C₂T_x复合,制备了不同比例的Ti₃C₂T_x–Mg Fe₂O₄复合材料。随后,采用X射线衍射、扫描电子显微镜、X射线光电子能谱分析、Fourier红外光谱等方法对Ti₃C₂T_x–Mg Fe₂O₄复合材料的结构和形貌进行了表征,研究了不同比例Ti₃C₂T_x–Mg Fe₂O₄复合材料的气敏性能。结果表明：2.5%(质量分数) Ti₃C₂T_x–Mg Fe     

二维Ti3C2Tx官能团微波等离子体调控及其气敏性能

采用液相溶液选择性刻蚀法制备风琴状二维碳化钛(Ti₃C₂T_x),并采用O₂–Ar微波等离子体在不同热处理温度下对Ti₃C₂T_x进行表面官能团调控。研究了不同等离子体处理温度下材料的微结构和表面官能团变化,探讨了Ti₃C₂T_x对甲醛和苯系物的气敏响应和选择性,从材料氧官能团变化角度探讨了可能的气体敏感机制。结果表明:O₂–Ar等离子体处理可增加Ti₃C₂T_x材料中的表面氧官能团含量,经500℃热处理样品在最佳工作温度下对0.01%(体积分数)甲醛响应可达到169,同时在室温下对甲醛也表现出良好的气敏性能。     

钠离子电池负极材料的储钠机制及性能研究进展

绿色能源的应用,促使着电化学储能与转换技术的飞速发展。锂离子电池作为储能领域最成功的二次离子电池之一,已被应用于各种电子产品中,但是由于锂资源短缺造成锂离子电池的成本增加,限制了其在大规模储能设备领域的应用。因此,寻找价格低廉、性能优异的二次离子电池是当下的研究热门之一。钠离子电池不仅拥有和锂离子电池相似的工作原理,而且还具有成本低、资源丰度大和可逆容量高的特点,有望成功地代替锂离子电池而应用于商业化生产。本工作主要综述了钠离子电池负极材料的性能研究进展,首先根据钠离子在负极材料存储方式不同,分析归纳了负极材料的插层反应、合金化反应和转换反应三种储钠机制,然后介绍了负极材料的结构修改、元素掺杂和材料复合三种改性方式,随后重点介绍了碳基材料、钛基材料、合金类材料、转换类材料和有机材料等几种关键的钠离子电池负极材料的电化学性能和所面临的问题,最后,以实际生产和工业应用为基础,展望了钠离子电池负极材料的研究方向。     

Synthesis of Chl@Ti3C2 composites as an anode material for lithium storage

Two-dimensional (2D) titanium carbide MXene Ti₃C₂ has attracted significant research interest in energy storage applications. In this study, we prepared Chl@Ti₃C₂ composites by simply mixing a chlorophyll derivative (e.g., zinc methyl 3-devinyl-3-hydroxymethyl- pyropheophorbide a (Chl)) and Ti₃C₂ in tetrahydrofuran, where the Chl molecules were aggregated among the multi-layered Ti₃C₂ MXene or on its surface, increasing the interlayer space of Ti₃C₂. The as-prepared Chl@Ti₃C₂ was employed as the anode material in the lithium-ion battery (LIB) with lithium metal as the cathode. The resulting LIB exhibited a higher reversible capacity and longer cycle performance than those of LIB based on pure Ti₃C₂, and its specific discharge capacity continuously increased along with the increasing number of cycles, which can be attributed to the gradual activation of Chl@Ti₃C₂ accompanied by the electrochemical reactions. The discharge capacity of 1 wt-% Chl@Ti₃C₂ was recorded to be 325 mA·h·g^–1 at the current density of 50 mA·g^–1 with a Coulombic efficiency of 56% and a reversible discharge capacity of 173 mA·h·g^–1 at the current density of 500 mA·g^–1 after 800 cycles. This work provides a novel strategy for improving the energy storage performance of 2D MXene materials by expanding the layer distance with organic dye aggregates.     

Ti3C2Tx/Ni/TiO2复合粉体的制备及吸波性能研究

采用热处理的方法制备出二维层状Ti3C2Tx/Ni/TiO2复合粉体,并利用TG-DSC、SEM、XRD和XPS对样品进行表征分析,通过矢量网络分析仪测试样品的电磁参数并模拟计算不同涂层厚度下样品的反射损耗值(RL).结果表明:随着热处理温度的升高,样品中TiO2质量含量增加;当热处理温度为300℃时,在频率f=17....     

Research progress on modification strategy of g-C3N4 and g-C3N4/Ti3C2 heterojunction

Graphite phase carbon nitride (g-C₃N₄) is a kind of metal-free semiconductor material with a forbidden band width of about 2.7 eV and has visible light response capability. Attributed to its good thermal and chemical stability, adjustable morphology and chemical structure, it is widely used in the field of photocatalysis. However, due to its low specific surface area and wide band gap, its response range to visible light is narrow and the recombination rate of photogenerated carriers is high, resulting in a low photocatalytic efficiency, which can be effectively improved by modification. The two-dimensional material Ti₃C₂ has a narrower band gap compared with other semiconductor materials, and the heterogeneous junction between Ti₃C₂ and g-C₃N₄ is expected to obtain a wider range of visible light absorption and higher photocatalytic efficiency. This article reviews the modification methods of g-C₃N₄ including morphology control, doping and constructing heterojunctions, as well as the action mechanism, preparation methods and applications of g-C₃N₄/Ti₃C₂ heterojunction in photocatalytic hydrogen evolution, organics degradation and synthesis, etc.     

g-C3N4的改性策略以及g-C3N4/Ti3C2异质结研究进展

石墨相氮化碳（g-C₃N₄）禁带宽度约为2.7 eV,具有可见光响应能力。由于其良好的热和化学稳定性,且形貌和化学结构可调,在光催化领域应用广泛。但由于其带隙宽,对可见光响应范围窄,且光生载流子的复合率高,导致其光催化效率低,可通过改性来改善。本文综述了对g-C₃N₄形貌调控、掺杂和构建异质结等改性策略,以及g-C₃N₄/Ti₃C₂异质结的作用机理、制备方法和在光催化析氢、有机物降解及合成等领域的应用。     

The prior rules of designing Ti3C2Tx MXene-based gas sensors

Working temperature, sensitivity, and selectivity are some of the characteristics of the applied gas sensors. How to design and fabricate an ideal gas sensor working at room temperature is still challenging and attracting lots of interest. Two-dimensional (2D) materials with ultra-thin structure have been demonstrated as a family of ideal candidates to achieve this goal. Among them, Ti₃C₂T_x MXene, a kind of layered sheet synthesized by selectively etching MAX phases materials, shows remarkable potential to be the sensitive materials solely or in a composite. However, their designing rules are still lacking critical thinking from the viewpoint of the intrinsic property of Ti₃C₂T_x MXene based materials. In this article, two critical features, i.e., the thickness of the sensitive materials, and the scope of the analytes, are elaborated towards Ti₃C₂T_x MXene based gas sensors after characterizing the performance of sensing reducing gases (NH₃ and CO) and oxidizing gas (NO₂). First, the thinner the Ti₃C₂T_x MXene sensitive layer, the better the sensitivity. Second, the Ti₃C₂T_x MXene based gas sensor is not suitable for strong and moderate oxidation gas due to its ease of oxidation. These two rules are demonstrated, and could be considered with priority both in the future researches and practical applications.     

电泳沉积法制备高能量密度的非对称平面微型超级电容器

首先采用光刻、蒸镀金的方法制备叉指电极,随后把合成的具有赝电容特性的二维MnO2和Ti3C2纳米片分别电泳沉积到叉指电极上,构建了非对称平面超级电容器.其中MnO2为正极,Ti3C2为负极,滴涂凝胶为电解质,并利用透明的聚二甲基硅氧烷薄膜封装成器件.通过能量色散X射线光谱(EDS)、傅里叶变换红外光谱(FT-IR)、扫...     

Decorating MXene with tiny ZIF-8 nanoparticles: An effective approach to construct composites for water pollutant removal

MXenes have attracted increasing research enthusiasm owing to their unique physical and chemical properties. Although MXenes exhibit exciting potential in cations adsorption due to their unique surface groups, the adsorption capacity is limited by the low specific surface area and undeveloped porosity. Our work aims at enhancing the adsorption performance of a well-known MXene, Ti₃C₂T_x, for methylene blue (MB) by decorating tiny ZIF-8 nanoparticles in the interlayer. After the incorporation of ZIF-8, suitable interspace in the layers resulting from the distribution of tiny ZIF-8 appears. When employing in MB, the adsorption capacity of composites can reach up to 107 mg·g^-1 while both ZIF-8 (3 mg·g^-1) and Ti₃C₂T_x (9 mg·g^-1) show nearly no adsorption capacity. The adsorption mechanism was explored, and the good adsorption capacity is caused by the synergistic effect of ZIF-8 and Ti₃C₂T_x, for neither of them is of suitable interspace or surface groups for MB adsorption. Our work might pave the way for constructing functional materials based on the introduction of nanoparticles into layered materials for various adsorption applications.     

石墨/TinO2n-1复合材料的制备及性能

在常压下,以钛白粉为原料,石墨为还原剂,采用碳热还原法制备了石墨/Ti_nO_2n-1复合材料。采用XRD系统分析了碳热还原过程中钛的价态变化规律;采用XPS、SEM、TEM分析了特定样品的形貌、结构和元素组成。XRD分析结果表明,控制不同的还原条件,可以得到不同n值的石墨/Ti_nO_2n-1复合材料,且还原过程的物相转变顺序为：TiO₂（锐钛型）、TiO₂（金红石型）、Ti₉O₁₇、Ti₈O₁₅、Ti₆O₁₁、Ti₅O₉和Ti₄O₇。在还原温度为1250℃,还原时间为20min,碳钛比为5∶10的条件下所制备的石墨/Ti_nO_2n-1复合材料的电阻率最低,其值为0.1465Ω·cm。吸附/光降解实验表明,石墨/Ti_nO_2n-1复合材料对亚甲基蓝的吸附能力比纯石墨显著增强,吸附去除率为纯石墨的1.40~3.20倍;石墨/Ti_nO_2n-1复合材料对亚甲基蓝具有光催化降解活性,但是其光降解能力低于锐钛型TiO₂;复合材料的催化降解速率常数最大值为0.0047min^-1。