Search query: Surface graft modification of transition metal carbides

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abstract: In spite of recent significant research into various two dimensional (2D) materials after the emergence of graphene, the development of a new 2D material that provides both high mobility and an appropriate energy band gap (which are crucial for various device applications) remains elusive. In this report, we demonstrate that the carrier transport behaviour of 2D Ti2CTx, which belongs to the family of 2D transition metal carbides and nitrides, can be tuned by modifying the surface group Tx OH, F, and O) Our results show that 2D Ti2C(OH)xFy and Ti2COx films can be obtained via simple chemical treatment, thermal annealing, and mechanical exfoliation processes. For the first time, we study the carrier transport properties of 2D Ti2CTx field effect transistors (FETs) obtaining the high field effect carrier mobilities of 10(4) cm(2) V( 1) s( 1) at room temperature. The temperature dependent resistivity of the Ti2COx film exhibits semiconductor like Arrhenius behaviour at zero gate voltage, from which we estimate the energy gap of 80 meV. One interesting feature of the FETs based on transition metal carbides is that the field effect mobility at room temperature is less sensitive to the measured transport gaps, which may arise from the dominant charge transport of activated carriers over the narrow energy gaps of the transition metal carbides. Our results open up the possibility that new 2D materials with high mobilities and appropriate band gaps can be achieved, and broaden the range of electronic device applications of Ti2CTx films.
author_names: Shen Lai

Jaeho Jeon

Sung Kyu Jang

Jiao Xu

Young Jin Choi

Jin-Hong Park

Euyheon Hwang

Sungjoo Lee
title: Surface group modification and carrier transport properties of layered transition metal carbides (Ti2CT(x) T: OH, F and O)
venue: Nanoscale
year: 2015

abstract: Correction for 'Surface group modification and carrier transport properties of layered transition metal carbides (Ti2CTx, T: OH, F and O) by Shen Lai, et al. Nanoscale, 2015, DOI: 10.1039/c5nr06513e.
author_names: Shen Lai

Jaeho Jeon

Sung Kyu Jang

Jiao Xu

Young Jin Choi

Jin-Hong Park

Euyheon Hwang

Sungjoo Lee
title: Correction: Surface group modification and carrier transport properties of layered transition metal carbides (Ti2CT(x) T: OH, F and O)
venue: Nanoscale
year: 2016

abstract: An acetylcholinesterase biosensor modified with graphene and transition metal carbides was prepared to detect organophosphorus pesticides. Cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy were used to characterize the electrochemical catalysis of the biosensor: acetylcholinesterase/chitosan transition metal carbides/graphene/glassy carbon electrode. With the joint modification of graphene and transition metal carbides, the biosensor has a good performance in detecting dichlorvos with a linear relationship from 11.31 mM to 22.6 nM and the limit of detection was 14.45 nM. Under the premise of parameter optimization, the biosensor showed a good catalytic performance for acetylcholine. Compared to the biosensors without modification, it expressed a better catalytic performance due to the excellent electrical properties, biocompatibility and high specific surface area of graphene, transition metal carbides. Finally, the biosensor exhibits good stability, which can be stored at room temperature for one month without significant performance degradation, and has practical potential for sample testing.
author_names: Bo Wang

Yiru Li

Huaying Hu

Wenhao Shu

Lianqiao Yang

Jianhua Zhang
title: Acetylcholinesterase electrochemical biosensors with graphene transition metal carbides nanocomposites modified for detection of organophosphate pesticides
venue: PloS one
year: 2020

abstract: With the advantages of zero carbon emission and high gravimetric energy density, hydrogen energy is recognized as a primary choice for the future energy supply. Electrochemical water splitting provides a promising strategy for effective and sustainable hydrogen production through renewable electricity, and one of the immediate challenges toward its large scale application is the availability of low cost and efficient electrocatalysts for the hydrogen evolution reaction (HER) Given the enormous effort in the exploration of potential transition metal carbide (TMC) electrocatalysts, the aim of this review is to summarise the recent advances in preparation and modification of TMC electrocatalysts. Special attention is focused on nanostructuring, hybridization and heteroatom doping that can regulate the surface properties of TMC electrocatalysts to improve catalytic performance. Additionally, the perspectives for the development of novel efficient TMC based catalysts are also proposed.
author_names: Han Zhang

Xiao-Hui Yang

Huijuan Zhang

Jin-Ling Ma

Zhengyong Huang

Juan Li
title: Recent advances in transition metal carbides: from controlled preparation to hydrogen evolution reaction application.
venue: Chemistry
year: 2020

abstract: The development of renewable energy conversion and storage devices, aiming at high efficiency, stable operation, environmental friendliness, and low cost goals, provides a promising approach to resolve the global energy crisis. Recently, two dimensional (2D) layered materials have drawn enormous attention due to their unique layered structure and intriguing electrical characteristics, which brings the unprecedented board applications in the fields ranging from electronic, optical, optoelectronic, thermal, magnetic, quantum devices to energy storage and catalysis. Graphene based 2D layered materials show promising applications in energy storage and conversion owing to their high specific surface area, which have been used for supercapacitor electrode materials based on the electrical double layer capacitance model. However, graphene has a limited value of theoretical electrical double layer capacitance when the whole surface area is fully utilized. Among several classes of 2D layered materials beyond graphene, transition metal dichalcogenides, transition metal carbides, and nitrides may exhibit excellent electrochemical properties due to the distinctive features of these 2D materials, such as large specific surface area, good hydrophilic nature, highly exposed active edge sites, and ease of intercalation and modification. Therefore, careful design and construction of these 2D compounds make them become potential candidates used for electrochemical supercapacitors and electrocatalytic hydrogen evolution. This review emphasizes the recent important advances of the 2D layered materials composed of transition metal dichalcogenides, transition metal carbides, and nitrides for supercapacitors and electrocatalysts. Furthermore, we discuss the challenges and perspectives in this energy field in terms of the classes of two dimensional layered materials.
author_names: Shuoguo Yuan

Sin-Yi Pang

Jianhua Hao
title: 2D transition metal dichalcogenides, carbides, nitrides, and their applications in supercapacitors and electrocatalytic hydrogen evolution reaction
year: 2020

abstract: Two dimensional transition metal carbides and nitrides known as MXenes, with a general formula of Mn+1Xn (n 1 3) integrate the advantages of metallic conductive transition metals with large groups of carbides, nitrides, or carbonitrides. They have led to a burgeoning research interest in biomedical applications due to their ultrathin structure and fascinating physiochemical (electronic, optical, magnetic, etc. properties. In this review, we summarize recent advances in biomedical applications for MXenes. We first introduce the preparation methods and surface modifications with respect to MXenes. Their unique properties are then elaborated. Thirdly, we highlight their various biomedical applications, such as with biosensors, antibacterial materials, bioimaging probes, therapeutics, and theranostics. In the end, the current challenges and new opportunities for MXenes in regard to their biomedical applications are also discussed.
author_names: Kai Huang

Zhongjun Li

Jing Lin

Gang Han

Peng Huang
title: Two dimensional transition metal carbides and nitrides (MXenes) for biomedical applications.
venue: Chemical Society reviews
year: 2018

abstract: The surface modification of 2D semiconducting materials, such as transition metal dichalcogenides (TMDCs) is becoming important for a diverse range of applications, such as biosensing, catalysis, energy generation and energy storage. Due to the chemical inertness of their basal plane, the surface modification of 2D TMDCs is mainly limited to their defective sites, or it requires a conversion of TMDC from its semiconducting into a metallic phase. In this work, we show that the basal plane of a 2D semiconductor molybdenum disulfide (MoS2) can be modified by electrochemical grafting of aryl diazonium salt, such as 3,5 bis(trifluoromethyl)benzenediazonium tetrafluoroborate. To investigate the applicability of this method, we perform electrografting on MoS2 nanoribbons by addressing them individually via a different electrode. High spatial selectivity of this method on the nanoscale opens the possibility for specific surface modification of neighboring 2D layers and nanostructures that are contacted by electrodes. This method could be potentially applicable to other 2D semiconducting materials that are active in the same potential window in which the electrochemical reduction of aryl diazonium salts occurs.
author_names: Martina Lihter

Michael Graf

Damir Ivekovi'c

Tzu-Hsien Shen

Yanfei Zhao

Vasiliki Tileli

Aleksandra Radenovic
title: Electrochemical Surface Modification of a 2D MoS2 Semiconductor
year: 2020

abstract: Abstract Two dimensional transition metal carbides and nitrides (MXenes) demonstrate excellent performances in various field as a result of their unique surface group structures and high electrical conductivity. In this work, we employ a simple strategy of surface group modification to optimize the semiconductor performance of a high conductivity Ti3C2Tx film for thermoelectric energy conversion. In the process, the hydrothermal treatment with different concentrations, temperatures, and types of alkali solutions has significant effects on the thermoelectric properties of Ti3C2Tx. As a result, the modified free standing Ti3C2Tx film maintained its originally high conductivity (1652 S cm 1) and the Seebeck coefficient is improved threefold, leading to an optimized power factor of 44.98 mW m 1K 2 at room temperature. This study provides a new method for the development of the thermoelectric performance of highly conductive MXene films.
author_names: Lan Lan Shen

Peipei Liu
title: Surface termination modification on high conductivity MXene film for energy conversion
year: 2020

abstract: Modifying MXene surfaces Unlike graphene and transition metal dichalcogenides, two dimensional transition metal carbides (MXenes) have many surface sites that can be chemically modified. Etching of the aluminum layer of a parent MAX phase Ti3AlC2 layered material with hydrofluoric acid leads to the MXene Ti3C2 with various surface terminations. Molten salts can achieve uniform chloride terminations, but these are difficult to further modify. Kamysbayev et al. show that etching of MAX phases in molten cadmium bromide leads to bromide terminated MXenes that can then be substituted with oxygen, sulfur, selenium, tellurium, and NH groups as well as with vacancy sites. The surface groups can alter electronic transport. For example, the Nb2C MXenes exhibit surface group dependent superconductivity. Science, this issue p. 979 Substitution and elimination reactions in molten inorganic salts modified two dimensional transition metal carbide surfaces. Versatile chemical transformations of surface functional groups in two dimensional transition metal carbides (MXenes) open up a previously unexplored design space for this broad class of functional materials. We introduce a general strategy to install and remove surface groups by performing substitution and elimination reactions in molten inorganic salts. Successful synthesis of MXenes with oxygen, imido, sulfur, chlorine, selenium, bromine, and tellurium surface terminations, as well as bare MXenes (no surface termination) was demonstrated. These MXenes show distinctive structural and electronic properties. For example, the surface groups control interatomic distances in the MXene lattice, and Tin+1Cn (n 1, 2) MXenes terminated with telluride (Te2 ligands show a giant >18% in plane lattice expansion compared with the unstrained titanium carbide lattice. The surface groups also control superconductivity of niobium carbide MXenes.
author_names: Vladislav Kamysbayev

Alexander S Filatov

Huicheng Hu

Xue Rui

Francisco Lagunas

Di Wang

Robert F Klie

Dmitri V Talapin
title: Covalent surface modifications and superconductivity of two dimensional metal carbide MXenes
venue: Science
year: 2020

abstract: Abstract Two dimensional transition metal carbides and nitrides (MXene) have shown outstanding performances in electrochemical energy storage, but their investigations of both mechanical and electrochemical performance for structural power systems are lack of being discussed. In this work, modified MXene films with mechanically strong structures and high electrochemical performance are obtained via directly annealing strategies. Due to the beneficial chemical composition on the surface and the structural variation under appropriate annealing treatment conditions, the modified Ti3C2Tx MXene electrode can deliver an ultrahigh volumetric capacitance of 1590 F cm 3 with a gravimetric value of 442 F g 1 at 0.5 A g 1, a good rate capability of 1030 F cm 3 at 20 A g 1, a cycling stability with a retention of 95.4% after 5000 cycles in the acid electrolyte and a high tensile strength of 32 MPa, demonstrating its great potential as a multifunctional electrode for structural energy and power systems. The influences of different electrolytes on the intercalation induced electrochemical process of modified MXene films were also probed. Furthermore, the assembled symmetric supercapacitor with the modified Ti3C2Tx MXene film demonstrates a favorable volumetric energy density of 15.2 Wh L 1 and a power density of 204.8 W L 1.
author_names: Xin Zhao

Zhe Wang

Jie Dong

Tao Huang

Qinghua Zhang

Lili Zhang
title: Annealing modification of MXene films with mechanically strong structures and high electrochemical performance for supercapacitor applications
year: 2020