共查询到19条相似文献,搜索用时 78 毫秒
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采用密度泛函数理论框架下的第一性原理研究了Ti3SnC2的电子结构,利用GGA-PW91基组对Ti3SnC2晶体结构进行了优化,并计算了Ti3SnC2的能带结构、总态密度和各原子的分态密度.对能带和总态密度的计算结果表明,Ti3SnC2在费米能级处电子态密度较高,材料表现出较强的金属性,同时材料的导电性为各向异性.Ti3SnC2各原子的分态密度图的计算结果表明,其导电性主要由Ti2的3d电子决定,Ti1的3d态电子、Sn的5p态电子和C的2p态电子也有少量贡献.决定材料电学性质的主要是Ti的3d、Sn的5p和C的2p态电子的p-d电子轨道杂化,而p-d电子轨道杂化成键则使材料具有比较稳定的结构. 相似文献
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Mxenes以其优异的比表面积、高导电率和组分可调性而受到广泛研究,并用作高效锂离子电池的电极材料。然而,其有限的存储容量以及锂离子扩散引起的剧烈晶格膨胀限制了MXenes作为电极材料的应用。本研究设计了具有代表性的MXene材料卤化(氟化、氯化或溴化)–Ti3C2。采用基于密度泛函理论的范德瓦耳斯修正的第一性原理计算方法研究了表面端基(T=F~–、Cl~–和Br~–)修饰对锂离子电池中Ti3C2负极的原子结构、电学性质、力学性质以及电化学性能的影响。研究表明, Ti3C2T2单层具有良好的结构稳定性、力学性质和导电性质。相比Ti3C2F2和Ti3C2Br2,Ti3C2Cl2单层具有较大的弹性模量(沿二维薄膜两个方向的弹性模量分别为321.70和329.43 N/m)、较低的锂离子扩... 相似文献
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随着电子设备和无线通讯的迅猛发展,电磁干扰问题也随之日益严重,迫切需要发展高性能的电磁屏蔽防护材料来减轻电磁波干扰危害.MXene(Ti3C2Tx)是一种新型二维材料,具有超高的电导率和活跃的化学活性表面,因而展现出极其优异的电磁屏蔽性能.本文重点介绍了Ti3C2Tx的制备方法、结构特性以及电磁屏蔽机理,客观地综述和评价了近年来国内外关于Ti3C2Tx基薄膜和三维多孔材料在电磁屏蔽应用方面的重要研究进展,并分析了目前存在的主要问题.此外,从Ti3C2Tx的制备、结构调控、设计组装等方面展望了Ti3C2Tx基电磁屏蔽材料的发展方向及趋势,包括发展低成本绿色环保且高效的Ti3C2Tx制备工艺、解决Ti3C2Tx不耐氧化的问题、设计新型Ti3C2Tx电磁屏蔽材料结构及探究其他种类的MXenes电磁屏蔽材料,为开发下一代高电磁屏蔽性能材料提供新的思路和指导. 相似文献
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驱动器具备质轻、柔软、微小、智能化等特点,能够通过感受外界刺激如光、电、温度、湿度等产生相应的力、位移或形变,在软机器人、智能穿戴设备、仿生工程等领域具备巨大的应用潜力。然而,驱动器也存在着响应灵敏性和稳定性方面的缺陷。MXene具有高导电性、表面官能团可调性和优越的力学性能,有望成为解决上述问题的关键。目前,MXene材料主要面临易氧化和相对较高的生产成本等挑战,相关研究处于早期阶段,需要进一步验证其实际应用潜力。因此,本文介绍了MXene及MXene基驱动器的制备方法,并梳理光热响应型驱动器、离子响应型驱动器、湿度响应型驱动器及其他响应型驱动器的研究进展,同时对MXene基驱动器未来的研究方向进行了展望。 相似文献
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通过化学溶液法一步制备锗/MXene复合材料,在MXene表面均匀负载了锗金属纳米颗粒。采用SEM和TEM对Ge/MXene复合材料进行了微观形貌分析,探索了复合材料的形成过程,结果表明,Ge/MXene复合材料是二维结构形貌,其元素分布均一。用Ge/MXene复合材料制备了电极,并组装成纽扣电池进行充放电性能测试,对电池的比容量、倍率、循环稳定性能进行了系统分析。测试结果表明,Ge含量为50%时的电化学性能最佳,0.2C下第5~100圈的容量稳定在1200 m Ah/g,载量为1 mg/cm2;载量提高到2 mg/cm2时的比容量依然能达到450 m Ah/g。 相似文献
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用GGA+U的方法研究了本征β-Ga2O3和Ti掺杂β-Ga2O3的电子结构和光学性能。晶格常数的计算值与实验值差别小于1%,本征β-Ga2O3的带隙计算值4.915eV,与实验值4.9eV一致。Ti替位Ga(1)位置和Ti替位Ga(2)位置的β-Ga2O3的价带最大值和导带最小值间隙分别为4.992eV和4.955eV,Ti掺杂引入的杂质带起到中间带作用,可以使电子从杂质带跃迁到导带和价带跃迁到杂质带。Ti掺杂β-Ga2O3中间带的存在使其成为潜在的宽光谱吸收太阳能电池材料。 相似文献
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运用第一性原理密度泛函理论(DFT)计算了不同交换关联势下单斜晶系β-Ga2O3的总能量、晶格常数、总态密度、分波态密度及能带结构。理论计算结果表明:单斜晶系β-Ga2O3在局域密度近似(LDA)和广义梯度近似(GGA)下的晶格常数和带隙与实验值基本相符,其中LDA近似得到的晶格常数与实验值更接近;β-Ga2O3比六方晶系结构的α-Ga2O3更加稳定,但带隙比α—Ga2O3略小;Cr掺杂导致β-Ga2O3禁带宽度变小,费米能级处的态密度不为零,即变为半金属。 相似文献
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Li4Ti5O12/C复合负极材料的一步固相合成及不同碳源的影响 总被引:1,自引:0,他引:1
采用固相合成的方法,以Li2CO3,TiO2为原料,分别以葡萄糖、柠檬酸、聚丙烯及三者的混合物作为碳源一步烧结合成了亚微米级的Li4Ti5O12/c复合负极材料,XRD结果显示其具有理想的尖晶石结构。研究结果表明,以葡萄糖作为碳源制备的Li4Ti5O12/c材料的性能最佳,其碳含量最高,为2.07%,0.5c和1c倍率下的放电容量分别达到了220和191mAh/g。 相似文献
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Haoyang Xu Ruixin Zheng Dayue Du Longfei Ren Xiaojuan Wen Xinxiang Wang Guilei Tian Chaozhu Shu 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(9):2206611
Rationally designing efficient catalysts is the key to promote the kinetics of oxygen electrode reactions in lithium-oxygen (Li-O2) battery. Herein, nitrogen-doped Ti3C2 MXene prepared via hydrothermal method (N-Ti3C2(H)) is studied as the efficient Li-O2 battery catalyst. The nitrogen doping increases the disorder degree of N-Ti3C2(H) and provides abundant active sites, which is conducive to the uniform formation and decomposition of discharge product Li2O2. Besides, density functional theory calculations confirm that the introduction of nitrogen can effectively modulate the 3d orbital occupation of Ti in N-Ti3C2(H), promote the electron exchange between Ti 3d orbital and O 2p orbital, and accelerate oxygen electrode reactions. Specifically, the N-Ti3C2(H) based Li-O2 battery delivers large discharge capacity (11 679.8 mAh g−1) and extended stability (372 cycles). This work provides a valuable strategy for regulating 3d orbital occupancy of transition metal in MXene to improve the catalytic activity of oxygen electrode reactions in Li-O2 battery. 相似文献
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Dongbin Xiong Xifei Li Zhimin Bai Shigang Lu 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(17)
Ti3C2Tx, a typical representative among the emerging family of 2D layered transition metal carbides and/or nitrides referred to as MXenes, has exhibited multiple advantages including metallic conductivity, a plastic layer structure, small band gaps, and the hydrophilic nature of its functionalized surface. As a result, this 2D material is intensively investigated for application in the energy storage field. The composition, morphology and texture, surface chemistry, and structural configuration of Ti3C2Tx directly influence its electrochemical performance, e.g., the use of a well‐designed 2D Ti3C2Tx as a rechargeable battery anode has significantly enhanced battery performance by providing more chemically active interfaces, shortened ion‐diffusion lengths, and improved in‐plane carrier/charge‐transport kinetics. Some recent progresses of Ti3C2Tx MXene are achieved in energy storage. This Review summarizes recent advances in the synthesis and electrochemical energy storage applications of Ti3C2Tx MXene including supercapacitors, lithium‐ion batteries, sodium‐ion batteries, and lithium–sulfur batteries. The current opportunities and future challenges of Ti3C2Tx MXene are addressed for energy‐storage devices. This Review seeks to provide a rational and in‐depth understanding of the relation between the electrochemical performance and the nanostructural/chemical composition of Ti3C2Tx, which will promote the further development of 2D MXenes in energy‐storage applications. 相似文献
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Shunlong Zhang Hangjun Ying Pengfei Huang Tiantian Yang Wei-Qiang Han 《Nano Research》2022,(3):2746-2755
Due to easy re-stacking,low yield of few-layered MXenes(f-MXenes),the applications of MXenes are mainly restricted in multi-layered MXenes(m-MXenes)state.Althou... 相似文献
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分别以蔗糖、可溶性淀粉作为碳源,采用固相法在N2气氛中制备尖晶石结构的Li4Ti5O12/C复合正极材料,通过X射线衍射(XRD),扫描电子显微镜(SEM)分析和电化学性能测试表征了Li4Ti5O12/C的晶体结构、表面形貌和电化学性能,结果表明,碳源的加入抑制了晶粒的生长,增大了材料的比表面积,增强了材料的电化学性能,其中,碳源为可溶性淀粉时,样品在0.1C下首次放电比容量达到了164.9mAhg^-1,在2.OCT首次放电比容量可达到125.4mAhg^-1,且循环性能良好。 相似文献
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Yaqian Deng Tongxin Shang Zhitan Wu Ying Tao Chong Luo Jiachen Liang Daliang Han Ruiyang Lyu Changsheng Qi Wei Lv Feiyu Kang Quan‐Hong Yang 《Advanced materials (Deerfield Beach, Fla.)》2019,31(43)
Gelation is an effective way to realize the self‐assembly of nanomaterials into different macrostructures, and in a typical use, the gelation of graphene oxide (GO) produces various graphene‐based carbon materials with different applications. However, the gelation of MXenes, another important type of 2D materials that have different surface chemistry from GO, is difficult to achieve. Here, the first gelation of MXenes in an aqueous dispersion that is initiated by divalent metal ions is reported, where the strong interaction between these ions and ? OH groups on the MXene surface plays a key role. Typically, Fe2+ ions are introduced in the MXene dispersion which destroys the electrostatic repulsion force between the MXene nanosheets in the dispersion and acts as linkers to bond the nanosheets together, forming a 3D MXene network. The obtained hydrogel effectively avoids the restacking of the MXene nanosheets and greatly improves their surface utilization, resulting in a high rate performance when used as a supercapacitor electrode (≈226 F g?1 at 1 V s?1). It is believed that the gelation of MXenes indicates a new way to build various tunable MXene‐based structures and develop different applications. 相似文献