Search Results (20)

Lithium–sulfur batteries (LSBs) are favorable candidates for advanced energy storage, boasting a remarkable theoretical energy density of 2600 Wh kg⁻¹. Moreover, several challenges hinder their practical implementation, including sulfur’s intrinsic electrical insulation, the shuttle effect of lithium polysulfides (LiPSs), sluggish redox kinetics of Li₂S₂/Li₂S, and the uncontrolled growth of Li dendrites. These issues pose significant obstacles to the commercialization of LSBs. A viable strategy to address these challenges involves using MXene materials, 2D transition metal carbides, and nitrides (TMCs/TMNs) as hosts, functional separators, or interlayers. MXenes offer exceptional electronic conductivity, adjustable structural properties, and abundant polar functional groups, enabling strong interactions with both S cathodes and Li anodes. Despite their advantages, current MXene synthesis methods predominantly rely on acid etching, which is associated with environmental concerns, low production efficiency, and limited structural versatility, restricting their potential in LSBs. This review provides a comprehensive overview of traditional and environmentally sustainable MXene synthesis techniques, emphasizing their applications in developing S cathodes, Li anodes, and functional separators for LSBs. Additionally, it discusses the challenges and outlines future directions for advancing MXene-based solutions in LSBs technology. Full article

In this paper, we developed models for 21 quinary high-entropy transition metal carbide ceramics (HETMCCs), composed of carbon and the transition metals Ti, Zr, Mo, V, Nb, W, and Ta, employing the Special Quasirandom Structures (SQS) method. We investigated how the transition metal elements influence lattice distortion, mixing enthalpy, Gibbs free energy of mixing, and the electronic structure of the systems through first-principles calculations. The calculations show that 21 systems can form a stable single phase, among which (TiMoVNbTa)C₅, (ZrMoNbWTa)C₅, and (MoVNbWTa)C₅ exhibit superior stability. The formation energy and migration energy of carbon vacancies in systems with strong single-phase stability were calculated to predict their radiation resistance. The formation energy of carbon vacancies is closely related to the types of surrounding transition metal elements, with values ranging between the maximum and minimum formation energies observed in binary transition metal carbides (TMCs). The range of migration energy for carbon vacancies is wider than that observed in TMCs, which can hinder their long-range migration and enhance the radiation resistance of the materials. Full article

The article presents research results on the possibility of shaping the structure and properties of Co-Cr-W-C-Ti alloys (type Stellite 6) using laser cladding technology. Cobalt-based alloys are used in several industries because they are characterized by high erosion, abrasion, and corrosion resistance, retaining these properties at high temperatures. To further increase erosion resistance, it seems appropriate to reinforce material by in situ synthesis of hard phases. Among the transition metal carbides (TMCs), titanium carbide is one of the hardest and can have a positive effect on the extension of the lifetime of components made from cobalt-based alloys. In this article, concentration of C, W, and Ti due to the possibility of in situ synthesis of titanium carbides was subjected to detailed analysis. The provided research includes macrostructure and microstructure analysis, X-ray diffraction (XRD), microhardness, and penetrant tests. It was found that the optimal concentrations of Ti and C in the Co-Cr-W-C alloy allow the formation of titanium carbides, which significantly improves erosion resistance for low impact angles. Depending on the concentrations of titanium, carbon, and tungsten in the molten metal pool, it is possible to shape the alloy structure by influencing to morphology and size of the reinforcing phase in the form of the complex carbide (Ti,W)C. Full article

Sensors play vital roles in industry and healthcare due to the significance of controlling the presence of different substances in industrial processes, human organs, and the environment. Electrochemical sensors have gained more attention recently than conventional sensors, including optical fibers, chromatography devices, and chemiresistors, due to their better versatility, higher sensitivity and selectivity, and lower complexity. Herein, we review transition metal carbides (TMCs) and transition metal oxides (TMOs) as outstanding materials for electrochemical sensors. We navigate through the fabrication processes of TMCs and TMOs and reveal the relationships among their synthesis processes, morphological structures, and sensing performance. The state-of-the-art biological, gas, and hydrogen peroxide electrochemical sensors based on TMCs and TMOs are reviewed, and potential challenges in the field are suggested. This review can help others to understand recent advancements in electrochemical sensors based on transition metal oxides and carbides. Full article

In this research, we report the synthesis of Si–TmC–B/PCD composites using Si, B, and transition metal carbide particles (TmC) as binders at high pressure and high temperature (HPHT method, 5.5 GPa and 1450 °C). The microstructure, elemental distribution, phase composition, thermal stability, and mechanical properties of PCD composites were systematically investigated. The Si–B/PCD sample is thermally stable in air at 919 °C. The initial oxidation temperature of the PCD sample with ZrC particles is as high as 976 °C, and it also has a maximum flexural strength of 762.2 MPa, and the highest fracture toughness of 8.0 MPa·m^1/2. Full article

Under DFT calculations, a systematic investigation is carried out to explore the structures and oxygen evolution reaction (OER) catalytic activities of a series of 2D single-atom catalyst (SAC) systems, which are constructed by doping the transition metal (TM) atoms in group VIII into the cavities of rigid phthalocyanine carbide (pc-C₃N₂). We can find that when Co, Rh, Ir and Ru atoms are doped in the small or large cavities of a pc-C₃N₂ monolayer, they can be used as high-activity centers of OER. All these four new TM@C₃N₂ nanostructures can exhibit very low overpotential values in the range of 0.33~0.48 V, even smaller than the state-of-the-art IrO₂ (0.56 V), which indicates considerably high OER catalytic activity. In particular, the Rh@C₃N₂ system can show the best OER performance, given that doped Rh atoms can uniformly serve as high-OER-active centers, regardless of the size of cavity. In addition, a detailed mechanism analysis was carried out. It is found that in these doped pc-C₃N₂ systems, the number of outer electrons, the periodic number of doped TM atoms and the size of the embedded cavity can be considered the key factors affecting the OER catalytic activity, and excellent OER catalytic performance can be achieved through their effective cooperation. These fascinating findings can be advantageous for realizing low-cost and high-performance SAC catalysts for OER in the near future. Full article

Dry reforming of hydrocarbons (DRH) is a pro-environmental method for syngas production. It owes its pro-environmental character to the use of carbon dioxide, which is one of the main greenhouse gases. Currently used nickel catalysts on oxide supports suffer from rapid deactivation due to sintering of active metal particles or the deposition of carbon deposits blocking the flow of gases through the reaction tube. In this view, new alternative catalysts are highly sought after. Transition metal carbides (TMCs) can potentially replace traditional nickel catalysts due to their stability and activity in DR processes. The catalytic activity of carbides results from the synthesis-dependent structural properties of carbides. In this respect, this review presents the most important methods of titanium, molybdenum, and tungsten carbide synthesis and the influence of their properties on activity in catalyzing the reaction of methane with carbon dioxide. Full article

Important applications of transition metal carbides (TMCs) are as wear resistant composite layers deposited by plasma transferred arc welding (PTAW) and laser methods. Growing interest in them has also been observed in additive manufacturing and in HEA technology (bulk composite materials and layers), and in the area of energy conversion and storage. This paper presents the results of comparative studies on interfacial interactions in the NiBSi−TMCs system for two border IVB and VIB TM groups of the periodic table. Model (wettability and spreadability) and application experiments (testing of the PTAW-obtained carbide particle−matrix boundaries) were performed. Fe from partially melted steel substrates is active in the liquid NiBSi−TMCs system. It was revealed that the interaction of TMCs with the liquid NiBSi matrix tends to increase with the group number, and from the top to bottom inside individual groups. Particles of IVB TMCs are decomposed by penetration of the liquid along the grain boundaries, whereas those of VIB are decomposed by solubility in the matrix and secondary crystallization. No transition zones formed at the interfacial boundaries of the matrix−IVB group TMCs, unlike in the case of the VIB group. The experimental results are discussed using the data on the TMC electronic structure and the physicochemical properties. Full article

Transition metal dichalcogenides (TMDs) are the auspicious inexpensive electrocatalysts for the hydrogen evolution reaction (HER) which has been broadly studied owing to their remarkable enactment, however the drought of factors understanding were highly influenced to hinder their electrocatalytic behavior. Recently, transition metal carbide (TMC) has also emerged as an attractive electrode material due to their excellent ionic and electronic transport behavior. In this work, Mo₂C@WS₂ hybrids have been fabricated through a simple chemical reaction method. Constructed heterostructure electrocatalyts presented the small Tafel slope of 59 and 95 mV per decade and low overpotential of 93 mV and 98 @10 mA·cm⁻² for HER in acidic and alkaline solution, respectively. In addition, 24-h robust stability with the improved interfacial interaction demonstrated the suitability of hybrid electrocatalyst for HER than their pure form of Mo₂C and WS₂ structures. The derived outcomes describe the generated abundant active sites and conductivity enhancement in TMC/TMD heterostructure along with the weaken ion/electron diffusion resistance for efficient energy generation applications. Full article

2-D transition metal carbides (TMCs)-based anode materials offer competitive performance in lithium-ion batteries (LIBs) owing to its excellent conductivity; cheaper, flexible uses; and superior mechanical stability. However, the electrochemical energy storage of TMCs is still the major obstacle due to their modest capacity and the trends of restacking/aggregation. In this report, the Mo₂C nanosheets were attached on conductive CNT network to form a hierarchical 2D hybrid structure, which not only alleviated the aggregation of the Mo₂C nanoparticle and facilitated the rapid transference of ion/electron, but also adapted effectually to the hefty volume expansion of Mo₂C nanosheets and prevented restacking/collapse of Mo₂C structure. Benefitting from the layered Mo₂@CNT hybrid structure, the charge/discharge profile produced a 200 mAh g⁻¹ discharge-specific capacity (second cycle) and 132 mAh g⁻¹ reversible-discharge discharge-specific capacity (after 100 cycles) at 50 mA g⁻¹ current density, with high-speed competency and superior cycle stability. The improved storage kinetics for Mo₂@CNT hybrid structure are credited to the creation of numerous active catalytic facets and association reaction between the CNT and Mo₂C, promoting the efficient electron transfer and enhancing the cycling stability. Full article

Good stability and reproducibility are important factors in determining the place of any material in their respective field and these two factors also enable them to use in various applications. At present, transition metal carbides (TMCs) have high demand either in the two-dimensional (2D) form (MXene) or as nanocomposites, nanoparticles, carbide films, carbide nano-powder, and carbide nanofibers. They have shown good stability at high temperatures in different environments and also have the ability to show adequate reproducibility. Metal carbides have shown a broad spectrum of properties enabling them to engage the modern approach of multifacet material. Several ways have been routed to synthesize metal carbides in their various forms but few of those gain more attention due to their easy approach and better properties. TMCs find applications in various fields, such as catalysts, absorbents, bio-sensors, pesticides, electrogenerated chemiluminescence (ECL), anti-pollution and anti-bacterial agents, and in tumor detection. This article highlights some recent developments in the synthesis methods and applications of TMCs in various fields. Full article

A large volume of research on lithium–oxygen (Li–O₂) batteries (LOBs) has been conducted in the recent decades, inspired by their high energy density and power density. However, these future generation energy-storage devices are still subject to technical limitations, including a squat round-trip efficiency and a deprived rate-capability, due to the slow-moving electrochemical kinetics of both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) over the surface of the cathode catalyst. Because the electrochemistry of LOBs is rather complex, only a limited range of cathode catalysts has been employed in the past. To understand the catalytic mechanisms involved and improve overall cell performance, the development of new cathode electrocatalysts with enhanced round-trip efficiency is extremely important. In this context, transition metal carbides and nitrides (TMCs and TMNs, respectively) have been explored as potential catalysts to overcome the slow kinetics of electrochemical reactions. To provide an accessible and up-to-date summary for the research community, the present paper reviews the recent advancements of TMCs and TMNs and its applications as active electrocatalysts for LOBs. In particular, significant studies on the rational design of catalysts and the properties of TMC/TMN in LOBs are discussed, and the prospects and challenges facing the continued development of TMC/TMN electrocatalysts and strategies for attaining higher OER/ORR activity in LOBs are presented. Full article

The electrolysis of water is considered to be a primary method for the mass production of hydrogen on a large scale, as a substitute for unsustainable fossil fuels in the future. However, it is highly restricted by the sluggish kinetics of the four-electron process of the oxygen evolution reaction (OER). Therefore, there is quite an urgent need to develop efficient, abundant, and economical electrocatalysts. Transition metal carbides (TMCs) have recently been recognized as promising electrocatalysts for OER due to their excellent activity, conductivity, and stability. In this review, widely-accepted evaluation parameters and measurement criteria for different electrocatalysts are discussed. Moreover, five sorts of TMC electrocatalysts—including NiC, tungsten carbide (WC), Fe₃C, MoC, and MXene—as well as their hybrids, are researched in terms of their morphology and compounds. Additionally, the synthetic methods are summarized. Based on the existing materials, strategies for improving the catalytic ability and new designs of electrocatalysts are put forward. Finally, the future development of TMC materials is discussed both experimentally and theoretically, and feasible modification approaches and prospects of a reliable mechanism are referred to, which would be instructive for designing other effective noble-free electrocatalysts for OER. Full article

Increasing demand for CO₂ utilization reactions and the stable character of CO₂ have motivated interest in developing highly active, selective and stable catalysts. Precious metal catalysts have been studied extensively due to their high activities, but their implementation for industrial applications is hindered due to their elevated cost. Among the materials which have comparatively low prices, transition metal carbides (TMCs) are deemed to display catalytic properties similar to Pt-group metals (Ru, Rh, Pd, Ir, Pt) in several reactions such as hydrogenation and dehydrogenation processes. In addition, they are excellent substrates to disperse metallic particles. Hence, the unique properties of TMCs make them ideal substitutes for precious metals resulting in promising catalysts for CO₂ utilization reactions. This work aims to provide a comprehensive overview of recent advances on TMCs catalysts towards gas phase CO₂ utilization processes, such as CO₂ methanation, reverse water gas shift (rWGS) and dry reforming of methane (DRM). We have carefully analyzed synthesis procedures, performances and limitations of different TMCs catalysts. Insights on material characteristics such as crystal structure and surface chemistry and their connection with the catalytic activity are also critically reviewed. Full article

Two-dimensional (2D) materials attracted widespread interest as unique and novel properties different from their bulk crystals, providing great potential for semiconductor devices and applications. Recently, the family of 2D materials has been expanded including but not limited to graphene, hexagonal boron nitride (h-BN), transition metal carbides (TMCs), and transition metal dichalcogenides (TMDCs). Metal-catalyzed chemical vapor deposition (CVD) is an effective method to achieve precise synthesis of these 2D materials. In this review, we focus on designing various binary alloys to realize controllable synthesis of multiple CVD-grown 2D materials and their heterostructures for both fundamental research and practical applications. Further investigations indicated that the design of the catalytic substrate is an important issue, which determines the morphology, domain size, thickness and quality of 2D materials and their heterostructures. Full article