MXene的制备及应用进展

近年来,随着可穿戴电子产品的飞速发展,柔性传感器也受到越来越多的关注。二维过渡金属碳/氮化物(MXene)因其具有良好的机械性能、优异的导电性和亲水性等优点,在电磁屏蔽、生物医药、能量转化与储存、传感器等领域都有广泛的应用。本综述首先对MXene的结构特点、制备方法以及其在多个领域的应用进行简介。进一步,重点围绕MXene在柔性压力/应变传感器、柔性温度传感器、柔性湿度传感器、柔性气体传感器等方面的研究,重点总结了MXene在柔性传感器领域的应用进展,最后,预测MXene基柔性传感器在未来会有更大的发展潜力。     

二维过渡金属硫族化合物在超级电容器中的研究进展

近年来, 过渡金属硫族化合物(TMDs)作为一种新兴的二维材料, 因其独特的层状结构及电学特性成为超级电容器电极材料的理想候选者之一. 本文介绍了二维TMDs的常用合成方法, 阐述了钼基、 钨基和钒基等TMDs在超级电容器中的研究进展, 分析了形貌、 尺寸和改性方法等因素对TMDs材料电化学性能的影响, 并对TMDs在超级电容器领域的工业化应用和挑战进行了总结与展望.     

Fe-based phosphate nanostructures for supercapacitors

Fe-based phosphates with excellent physical and chemical features are potential electrode materials for supercapacitors.In this work,we successfully synthesized Fe-based phosphates with different dimensions,morphologies,and compositions by one-step hydrothermal method.Influence factors on the chemical composition and morphology of the as-prepared materials were explored and the energy storage performance of the as-prepared samples were tested under the traditional three electrode system.Two-dimensional(2 D) iron metaphosphate(Fe(PO_3)_3) showed the best electrochemical performance.For Fe(PO_3)_3 electrode mate rials,the layered structure can provide a larger specific surface area than the bulk structure,which is conducive to the diffusion and transport of electrolyte ions during charging-discha rging and further improve s the rate perfo rmance and cycle stability of supe rcapacito r.2 D Fe(PO_3)_3 and activated carbon were used as electrode materials to construct a 2 D Fe(PO_3)_3//AC supercapacitor.The supercapacitor showed high energy density,high power density,and excellent cycling stability,which indicates 2 D Fe(PO_3)_3 is a promising electrode material for supercapacitors.     

Synthesis and Utilization of MXene/MOF Hybrid Composite Materials

Metal-organic frameworks(MOFs)are crystalline porous architectures formed by the coordination of organic ligands with metal ions or clusters.MOFs are notable for their vast surface area,abundant active sites,high porosity,and tunable properties.However,their application in energy storage and catalysis is impeded by limited conductivity and chemical stability.A promising approach to mitigating these constraints is the integration of MOFs with other functional or conductive materials.MXenes,with their distinctive layered structure,exceptional electrical conductivity,and rich surface functional groups,provide numerous advantages when combined with MOFs.This review encapsulates the synthesis methodologies of MXene/MOF composites and explores their applications across various domains,including lithium-ion batteries,supercapacitors,lithium-sulfur batteries,zinc-ion batteries,electrocatalysts,and photocatalysts.     

MXene的制备及其复合材料在能源光催化领域的应用进展

MXene作为一种拥有层状结构的二维材料,具有良好的吸附催化性能、较宽的光吸收范围、高导热性、高硬度、高熔点、高导电性以及大比表面积等物理和化学特性,在储能、催化、润滑、抗菌、电磁屏蔽等领域有着较高应用价值。本文着重介绍了由前驱体MAX相获得MXene的制备方法,综述了MXene复合材料在光催化固氮、析氢、CO₂还原等能源光催化领域的应用进展。     

二氧化锰与二维材料复合应用于超级电容器

现如今世界正面临着与能源相关的一系列问题与挑战,科学家们致力于研究绿色高性能的能量存储器件以适应当前乃至以后长久可持续创新发展的需要。超级电容器作为一种新型的绿色能源储存装置,具有功率密度大、理论比电容高、充放电速度快、循环寿命长、安全性高、环境友好且经济等优点,为人类解决能源危机提出了可能。电极材料是影响超级电容器性能的重要因素。近些年,由于二氧化锰基超级电容器具有理论比电容高、化学稳定性好、环境友好等特点被广泛研究。同时多种二维材料也继石墨烯后被相继用作超级电容器电极材料,具有二维结构特征材料在提高双电层电容器的能量密度、改善赝电容电容器方面发挥着重要作用。实现高比电容和高倍率性能,将二氧化锰与二维材料复合将不失为一个有前景的选择。本文系统介绍了以石墨烯为代表的各类二维材料与二氧化锰复合物在超级电容器中的应用研究,并聚焦于这些二维材料与二氧化锰复合后所展现的优异电化学性能。     

二维M_2XO_(2-2x)(OH)_(2x)(M=Ti,V;X=C,N)析氢催化活性的第一性原理研究

MXene是一种新型的二维析氢催化材料,其表面容易被亲水基团O和OH混合覆盖。我们基于第一性原理计算的方法,研究了M_2XO_(2-2x)(OH)_(2x)(M=Ti,V;X=C,N)的析氢催化活性。计算结果显示,M_2XO_(2-2x)(OH)_(2x)的析氢催化活性与其表面OH覆盖率(X)密切相关。对Ti_2CO_(2-2x)(OH)_(2x)来说,OH覆盖率不超过1/3时,具有优异的析氢催化活性。对Ti_2NO_(2-2x)(OH)_(2x)、V_2CO_(2-2x)(OH)_(2x)和V_2NO_(2-2x)(OH)_(2x)来说,OH覆盖率分别达到4/9、1/3和5/9时,才具有最佳的析氢催化活性。接着,电荷分析显示OH覆盖率会显著影响M_2XO_(2-2x)(OH)_(2x)活性位点O基团的电荷量。最后,我们从态密度的角度揭示了析氢催化活性变化的原因,即活性位点O基团的氧化性随OH覆盖率的增大而被削弱。因此,本文提出了调节表面OH覆盖率来获取M_2XO_(2-2x)(OH)_(2x)最佳析氢催化活性状态的方法,这在工业制氢生产过程中具有重要的应用价值。     

二维纳米片层孔洞化策略及组装材料在超级电容器中的应用

功率密度高、倍率性能优异和循环性能好等特性使得超级电容器在储能领域显示了巨大的应用前景。尽管二维层状材料剥离形成的纳米片层不仅可为电化学反应提供独特的纳米级反应空间,而且由其组装的层状纳米电极材料具有化学和结构上的氧化还原可逆性及纳米片层水平方向上离子或电子快速传输通道。但是,纳米片层组装电极材料在纳米片层垂直方向上离子或电子传输存在障碍,对于超级电容器功率密度和能量密度的提高及实现快速能量储存非常不利。因此,如何通过改善离子或电子的快速传输,实现超级电容器大功率密度下的高能量密度是超级电容器电极材料发展的方向之一。本文主要综述了二维层状材料剥离成纳米片层,纳米片层孔洞化策略及组装孔洞化材料在超级电容器电极材料中的应用。纳米层孔洞化技术是改善层状电极材料在纳米片层垂直方向离子或电子传输的有效手段,为实现高比电容下的高倍率性能超级电容器电极材料制备提供了方法学。最后,对开发大功率密度下的高能量密度超级电容器电极材料提出了展望。     

Intertwined Titanium Carbide MXene within a 3 D Tangled Polypyrrole Nanowires Matrix for Enhanced Supercapacitor Performances

The exploration of the rational design and synthesis of unique and robust architectured electrodes for the high capacitance, rate capability, and stability of supercapacitors is crucial to the future of energy storage technology. Herein, an in situ synthesis of multilayered titanium carbide MXene tightly caging within a 3 D conducting tangled polypyrrole (PPy) nanowire (NW) network is proposed as an effective strategy to prevent the aggregation of MXene, profoundly enhancing the electrochemical performance of the supercapacitor. Owing to the beneficial effects of an ideal 3 D interconnected porous structure and high electrical conductivity, the obtained electrode exhibits fast charge and ion transport kinetics as well as full usage of active material. As expected, the 3 D Ti₃C₂T_x@PPY NW exhibits a specific capacitance five times higher than that of pristine MXene (610 F g⁻¹), a good rate capability up to a current density of 25 A g⁻¹, and excellent stability with 100 % retention after 14 000 cycles at 4 A g⁻¹, outperforming the known state-of-the-art MXene-based supercapacitor. Our work provides a facile method for enhancing the performance of MXene-based energy storage devices.     

Ti3C2Tx MXene compounds for electrochemical energy storage

Since their discovery in 2011, MXene compounds, and in particular the Ti₃C₂-based phases, have gained increasing interest from researchers leading to over 2000 scientific works in 2020. The peculiar morphological, charge transport, and surface properties make the MXenes ideal materials for energy storage applications such as active material in alkaline ion batteries and supercapacitors, as conductive or buffer agent in composite electrodes for high energy applications, and as electrocatalytic materials for oxygen evolution or redox flow batteries. Among this almost endless literature, this work focuses on 5 recent articles (2019/2020) that summarize the potential of MXenes in different energy storage applications, also resuming the most promising preparatory routes regarding industrial scalability.     

Enhancement of the photocatalytic activity and electrochemical property of graphene-SrWO4 nanocomposite

SrWO₄ is a promising candidate as not only photocatalyst for the removal of organic pollutants from water, but also electrode material for energy storage devices. However, the drawbacks of its poor adsorptive performance, low electrical conductivity, and high recombination rate of photogenerated electron-hole pair impede its practical applications. In this work, we have developed a new graphene/SrWO₄ nanocomposite synthesized via a facile chemical precipitation method. Characterizations show that SrWO₄ nanoparticles with 80 nm or so deposited on the surface of graphene nanosheets. Graphene nanosheets in the graphene-SrWO₄ hybrid could increase adsorptive property, improve the electrical conductivity of hybrid, and reduce the recombination of electron-hole pairs. As a kind of photocatalyst or electrode material for supercapacitor, the binary graphene-SrWO₄ hybrid presents enhanced photocatalytic activity and electrochemical property compared to pure SrWO₄.