Transition Metal Nitrides Research Articles

Preparation and Lithium Storage Properties of MOF‐Derived Bimetallic Sulfide ZnxInyS/MXene Composites

Nanostructured metal sulfides (MSs) are considered promising anode materials for Li‐ion batteries (LIBs) due to their high specific capacity and abundant raw material resources. However, the practical application of these materials faces challenges such as poor conductivity and volume expansion. To address these issues and enhance the performance of LIBs, it is crucial to tackle the structural design problem associated with ZnxInyS anode material. The utilization of metal sulfides derived from metal‐organic frameworks (MOFs) not only improves conductivity but also mitigates the issue of volume expansion in metal sulfides. Furthermore, connecting the metal sulfides derived from MOF to various conductive substrates can further enhance their conductivity. Two‐dimensional transition metal carbides and nitrides (MXenes), a novel type of 2D material with plentiful functional groups and chemical properties, offer great potential. In this study, we have strategically constructed ZnxInyS/MXene heterostructures by combining the advantages of 2D Ti3C2TX nanosheets and bimetallic MOF structures. The results demonstrate that due to the synergistic effect between MXene and heterostructure, a significant number of lattice defects and ample buffer space are provided, resulting in excellent lithium storage performance and fast ion diffusion kinetics for the electrode.

A review on MXene (Ti3C2Tx) composites with varied sizes of carbon for supercapacitor applications

MXenes belongs to a family of two‐dimensional (2D) layered transition metal carbides or nitrides which shows outstanding potential for various energy storage applications because of their high‐specific surface area, phenomenal electrical conductivity, outstanding hydrophilicity, and variable terminations. Of these different types of MXenes, the most widely studied member is Ti3C2Tx especially in supercapacitors (SCs). However, due to the problem of stacking and oxidation in MXene sheets, significant loss of electrochemically active sites happens. To overcome these issues, incorporation of carbon materials is carried out into MXenes for enhancing its electrochemical performance. This review aims to introduce various common strategies employed in synthesizing Ti3C2Tx, followed by a brief overview of latest developments in fabricating Ti3C2Tx/carbon electrode materials for SCs. The composition of Ti3C2Tx/carbon are summarized based on different dimensions of carbons, such as 0D carbon dots, 1D carbon nanotubes and fibers, 2D graphene, and 3D carbon materials (activated carbon, polymer‐derived carbon, etc.). Further, this review also aims in highlighting several insights on fabrication of novel MXenes/carbon composites as electrodes for application in SCs.

Ionic-Liquid Synthesis of Atomic Molybdenum Nitride Clusters as Bifunctional Oxygen Reduction and Evolution Reactions Electrocatalysts for Alkaline Zn-Air Battery.

Transition-metal nitrides (TMNs) have garnered considerable attention for energy conversion applications owing to their exceptional electronic structures and high catalytic activities. However, the scarcity of active sites in TMNs impedes their large-scale application. This study describes the use of wetness impregnation and ionic-liquid methods to enhance the electrocatalytic efficiency of molybdenum nitride (MoN) atomic clusters finely dispersed on nitrogen-doped carbon (MoN@NC) substrates. The as-synthesized electrocatalysts feature atomically dispersed MoN clusters, achieving an impressive onset potential of 0.93 V vs. RHE for the oxygen reduction reaction (ORR) and maintaining an overpotential of just 295 mV at a current density of 10 mA/cm2 for the oxygen evolution reaction (OER). The MoN@NC-based zinc-air battery demonstrated a high-power density of 151 mW/cm2, a robust specific discharge capacity of 759 mAh/gZn at 20 mA/cm2, and superior charge-discharge cycling stability exceeding 190 cycles. The detailed experimental characterization revealed that the uniformly dispersed MoN clusters served as the primary active sites driving the observed catalytic performance. Additionally, the present findings suggested significant correlations between the phase of the material, crystallization, atomic cluster distribution, support porosity, and nitridation temperature. These insights are expected to refine strategies for achieving atomically dispersed nitrides with optimized ORR performance.

HF-free low-temperature synthesis of MXene for electrochemical hydrogen production

MXenes [two-dimensional (2D) transition-metal carbides, nitrides and carbonitrides] are gaining significant interest as alternative electrocatalysts for the hydrogen evolution reaction due to their excellent properties such as high electrical conductivity, large surface area and chemical stability. MXenes are traditionally synthesized using hydrofluoric acid (HF), which raises safety and environmental concerns due to its highly corrosive and toxic nature. HF introduces fluoride functional groups on the surface of MXenes, and these have been reported to have a detrimental effect on electrocatalysis. As a result, there is growing interest in developing MXenes through non-fluoride routes. Here, we report room-temperature, HF-free, wet-chemical synthesis of MXene using a mixture of hydrogen peroxide and chromium chloride. The newly prepared CH-MXenes possess hydrophilic functionalities (-Cl, -OH and =O). Key advantages of the CH route over HF-based synthesis include the elimination of an additional delamination step, the prevention of MXene restacking via chloride functionalities and the consistent production of high-quality 2D MXenes with a reproducible flake size (∼650 nm). These CH-MXenes exhibit a high surface area, excellent conductivity and enhanced chemical stability, making them suitable for various energy and other applications.

Computational prediction of novel two-dimensional tungsten nitride superconductors.

Transition metal nitrides are well-known 3D superconductor materials. However, there is a lack of knowledge related to their two-dimensional (2D) counterparts, which have several potential technological applications. 
In this work, we predict, using an evolutionary algorithm coupled with a first-principles approach, a set of novel 2D superconductive structures based on tungsten nitride. 
Through a systematic process including energetic and dynamical analysis, three thermodynamically stable compositions along with metastable compounds were studied in the following stoichiometries: W$_4$N$_2$, W$_2$N$_2$, and W$_2$N$_3$. Their superconductive temperature ($T_c$) values, estimated by means of the Eliashberg superconductive theory and the McMillan equation, range from 2.3 to 21.6 K, where the highest $T_c$ value corresponds to a W$_2$N$_3$ metastable hexagonal system. A systematic analysis of the structural, electronic, vibrational and electron-phonon properties, allowed us to recognize the variables that modulate the $T_c$ in theses systems. The superconductive behavior is strongly affected by changes in the nitrogen density of states at Fermi level, the electron-phonon coupling constant and the lattice symmetry. The present results aim to encourage further theoretical and experimental efforts over non fully explored superconductors in two dimensions.

Enhanced Cooperative Generalized Compressive Strain and Electronic Structure Engineering in W-Ni3N for Efficient Hydrazine Oxidation Facilitating H2 Production.

As promising bifunctional electrocatalysts, transition metal nitrides are expected to achieve an efficient hydrazine oxidation reaction (HzOR) by fine-tuning electronic structure via strain engineering, thereby facilitating hydrogen production. However, understanding the correlation between strain-induced atomic microenvironments and reactivity remains challenging. Herein, a generalized compressive strained W-Ni3N catalyst is developed to create a surface with enriched electronic states that optimize intermediate binding and activate both water and N2H4. Multi-dimensional characterizations reveal a nearly linear correlation between the hydrogen evolution reaction (HER) activity and the d-band center of W-Ni3N under strain state. Theoretically, compressive strain enhances the electron transfer capability at the surface, increasing donation into antibonding orbitals of adsorbed species, which accelerates the HER and HzOR. Leveraging both compressive strain and the modified electronic structure from W incorporation, the W-Ni3N catalysts demonstrate outstanding bifunctional performance, achieving overpotentials of 46mV for HER at 10mA cm-2 and 81mV for HzOR at 100mA cm-2. Furthermore, W-Ni3N catalyst achieves efficient overall hydrazine splitting at a low cell voltage of 0.185V for 50mA cm-2, maintaining stability for ≈450 h. This work provides new insights into the dual engineering of strain and electronic structure in the design of advanced catalysts.

Surface Structure Evolution of Bimetallic Nickel Tungsten Nitride (Ni2W3N) for High Performance Hydrogen Evolution

Bimetallic transition metal nitride (TMN)-based electrocatalysts have demonstrated potential for the hydrogen evolution reaction (HER) in alkaline electrolytes. However, simpler synthesis methods and a deeper understanding of the origin of...

Investigating the formation of metal nitride complexes employing a tetradentate bis-carbene bis-phenolate ligand.

The synthesis of MnV and CrV nitride complexes of a pro-radical tetradentate bis-phenol bis-N-heterocyclic carbene ligand H2LC2O2 was investigated. Employing either azide photolysis of the MnIII precursor complex MnLC2O2(N3) or a nitride exchange reaction between MnLC2O2(Br) and the nitride exchange reagent Mnsalen(N) failed to provide a useful route to the target nitride MnLC2O2(N). Experimental results support initial formation of the target nitride MnLC2O2(N), however, the nitride rapidly inserts into a Mn-CNHC bond. A second insertion reaction results in the isolation of the doubly inserted ligand product [H2LC2O2(N)]+ in good yield. In contrast, the Cr analogue CrLC2O2(N) was readily prepared and characterized by a number of experimental methods, including X-ray crystallography. Theoretical calculations predict a lower transition state energy for nitride insertion into the M-CNHC bond for Mn in comparison to Cr, and in addition the N-inserted product is stabilized for Mn while destabilized for Cr. Natural bond order (NBO) analysis predicts that the major bonding interaction (π MN → σ* M-CNHC) promotes nucleophilic attack of the nitride on the carbene as the major reaction pathway. Finally, one-electron oxidation of CrLC2O2(N) affords a relatively stable cation that is characterized by experimental and theoretical analysis to be a metal-oxidized d0 CrVI species.

Theoretical insights and design of MXene for aqueous batteries and supercapacitors: status, challenges, and perspectives.

Aqueous batteries and supercapacitors are promising electrochemical energy storage systems (EESSs) due to their low cost, environmental friendliness, and high safety. However, aqueous EESS development faces challenges like narrow electrochemical windows, irreversible dendrite growth, corrosion, and low energy density. Recently, two-dimensional (2D) transition metal carbide and nitride (MXene) have attracted more attention due to their excellent physicochemical properties and potential applications in aqueous EESSs. Understanding the atomic-level working mechanism of MXene in energy storage through theoretical calculations is necessary to advance aqueous EESS development. This review comprehensively summarizes the theoretical insights into MXene in aqueous batteries and supercapacitors. First, the basic properties of MXene, including structural composition, experimental and theoretical synthesis, and advantages in EESSs are introduced. Then, the energy storage mechanism of MXene in aqueous batteries and supercapacitors is summarized from a theoretical calculation perspective. Additionally, the theoretical insights into the side reactions and stability issues of MXene in aqueous EESSs are emphasized. Finally, the prospects of designing MXene for aqueous EESSs through computational methods are given.

Innovative applications of MXenes in dialysis: enhancing filtration efficiency.

MXenes, a family of two-dimensional transition metal carbides and nitrides, exhibit exceptional properties such as high electrical conductivity, large surface area, and chemical versatility, making them ideal candidates for various dialysis applications. One prominent application of MXenes lies in the efficient removal of toxic metals and harmful dyes from wastewater. Their unique structure allows for rapid adsorption and selective separation, significantly improving purification processes. MXenes show great promise in the therapeutic management of acute kidney injury, where their biocompatibility and ability to facilitate toxin removal can mitigate damage to renal tissues. In hemodialysis, MXenes can enhance membrane performance through improved permeability and selectivity, leading to more effective clearance of waste products. Despite the potential of MXene-based composites in dialysis applications, several challenges loom large on the horizon. The stability of MXenes in physiological environments is a critical concern, as they can undergo oxidation or degradation, which may compromise their functionality over time. The scalability of synthesis processes remains a significant barrier; producing high-quality MXene materials in sufficient quantities for clinical use is not yet fully realized. Moreover, ensuring biocompatibility is paramount, as any adverse reactions could lead to inflammation or other complications in patients. The integration of MXenes into existing dialysis systems requires meticulous engineering to maintain optimal filtration properties while avoiding clogging or fouling. The future of MXenes and their composites in dialysis presents a promising horizon, teeming with potential innovations. The development of hybrid materials that utilize MXenes alongside other nanomaterials can lead to multifunctional systems, capable of addressing multiple challenges faced in dialysis treatments. Advancements in fabrication techniques may allow for tailored porosity, enabling customized dialysis solutions for individual patients. Research into surface modifications and composites can enhance their stability and functionality, potentially overcoming current limitations. The purpose of this review is to provide a comprehensive understanding of the current landscape of MXenes in dialysis, highlighting their applications, challenges, and future directions. This review explores the diverse applications of MXenes in the field of dialysis, focusing on their roles in the removal of toxic metals and dyes, therapy for acute kidney injury, and hemodialysis enhancement.

Prospects of Band Structure Engineering in MXenes for Active Switching MXetronics: Computational Insights and Experimental Approaches.

MXenes, two-dimensional (2D) transition metal carbides and nitrides, have shown promise in a variety of applications. The use of MXenes in active electronic devices is restricted to electrode materials due to their metallic nature. However, MXenes can be modified to be semiconducting and can be used for next-generation channel materials. The inherent metallic characteristics of pristine Mn+1Xn-structured MXene can be tuned to semiconducting by (i) functionalizing MXenes with different moieties, (ii) applying external strain, and (iii) varying the composition. These strategies effectively modify the metallic electronic structure of MXene into a semiconducting one. This review focuses on the potential of tuning the electronic band structure of MXenes by surface functionalization, strain engineering, and compositional variation. The computational and experimental approaches to tuning the electronic band structure using these strategies are discussed in detail. In addition, the experimental methods which can be used to prepare semiconducting MXenes are described.

Modulation of Ti3C2Tx interlayer spacing and functional groups by Lewis‐basic halides and their effects on Li+ storage properties

AbstractSurface and interfacial chemistry play a vital role in shaping the properties of two‐dimensional transition metal carbides and nitrides (MXenes). This study focuses on utilizing Lewis‐basic halides (LiCl/KCl) for thermal treatment of multilayered Ti3C2Tx, leading to the simultaneous modulation of interlayer spacing and surface functional groups. Compared to the pristine Ti3C2Tx, the LiCl/KCl treated sample (heating temperature: 450°C, denoted as LK‐Ti3C2Tx‐450) showcases a remarkable increase in the interlayer spacing and synergistic optimization of the functional groups. These modifications endow LK‐Ti3C2Tx‐450 with enhanced electrochemical properties, rendering it as a promising anode candidate for lithium‐ion batteries. The increased interlayer spacing is particularly advantageous, as it facilitates efficient and rapid Li+ diffusion, a vital factor in enhancing the performance of energy storage devices.

The Impact of Laser Irradiation on Thin ZrN Films Deposited by Pulsed DC Magnetron Sputtering.

Transition metal nitrides have extensive applications, including magnetic storage devices, hardware resistance coatings, and low-temperature fuel cells. This study investigated the structural, electrical, and mechanical properties of thin zirconium nitride (ZrN) films by examining the effects of laser irradiation times. Thin ZrN films were deposited on glass substrates using pulsed DC magnetron sputtering and irradiated with a diode laser for 6 and 10 min. Characterization was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), nanoindentation, and four-point probe techniques. Extended laser irradiation times resulted in increased numbers of peaks on XRD analysis, indicating enhanced crystalline behavior of thin ZrN film. SEM analysis revealed surface voids, while HRTEM showed nanostructured ZrN with uniform plane orientation. The electrical properties of the thin ZrN film improved with extended laser irradiation, as demonstrated by a reduction in sheet resistance from 0.43 × 109 Ω to 0.04 × 109 Ω. Additionally, nanoindentation tests revealed an increase in hardness, rising from 8.91 GPa to 9.36 GPa.

MgCl2-facilitated synthesis and highly efficient oxygen reduction performance of Ta3N5/C catalyst

Transition metal nitrides (TMNs) are considered potential candidates for the oxygen reduction reaction (ORR) in metal batteries. Herein, we report a novel Ta3N5/C catalyst that was prepared using MgCl2—a component that could modulate the electronic structure and geometry and induce Ta-N bond formation, as suggested by density functional theory (DFT) calculations. The prepared Ta3N5/C catalyst exhibits good ORR performance in alkaline electrolytes, and has a higher stability (ΔE1/2= −17mV) after the 2000-cycle accelerated degradation test and a significantly enhanced methanol resistance compared to a 20% Pt/C catalyst or Ta2O5/NC. DFT calculations indicate that Ta3N5 has a smaller band gap and larger d-electron distribution compared to Ta2O5 catalysts. These features ensure an outstanding conductivity and a fast-electron-transfer ability during the ORR. This work provides new strategies for designing novel electrocatalysts for metal batteries.

Two-Dimensional MXene-Based Functional Composites for Photocatalysts: Current Status and Perspectives

Abstract: MXenes, as novel two-dimensional (2D) transition metal carbides, nitrides or carbonitrides, have excellent metal conductivity, high carrier mobility, and surface-terminated groups regulated band structure. It can be thus used as a cocatalyst in photocatalytic systems to improve the photocatalytic properties. This review represented recent research progress on the controllable construction of MXene-based functional composites with zero-dimensional (0D), one-dimensional (1D), 2D, and three-dimensional (3D) semiconductor photocatalysts and their applications for photocatalysts. Extensive information related to 2D MXene-Based composites for photocatalysts and their associated patents were collected. The construction methods and photocatalytic enhancement mechanisms of 2D MXene-based composite photocatalysts were given. Due to their excellent physical and chemical properties, 2D MXene composites have been widely used in pollutant removal, hydrogen production, CO2 reduction, and nitrogen fixation. Through the construction of 2D MXene-based functional composite photocatalysts with novel structures and excellent performance, it provides a new perspective for the design and construction of high-efficiency photocatalysts. The future research directions of MXene-based composite photocatalysts was proposed.

Promising antibacterial performance of Ag-nanoparticles intercalated Nb2CTx MXene towards E. coli and S. aureus

MXenes are a group of two-dimensional (2D), atomically thin transition metal carbides, nitrides and carbon nitrides with a variety of desirable characteristics. Due to their exceptional physiochemical characteristics and ultrathin lamellar structure, MXenes have shown excellent antibacterial capabilities. Two-dimensional Nb2CTx MXene has been recently analyzed for potential applications in antibacterial materials. Due to the development of antibiotic-resistant bacteria further materials or composite materials need to be explored. In this work, we report the antibacterial properties of a composite of Nb2CTx and silver, synthesized using electrostatic self-assembly method. This work also demonstrates the optimization of the etching of Nb2CTx MXene for different time intervals and delamination of Nb2CTx MXene by using two different solvents i.e., tetramethylammonium hydroxide (TMAOH) and isopropyl amine. The antibacterial characteristics of Nb2CTx MXene, delaminated Nb2CTx MXene and Nb2CTx-Ag composite of 1:1 and 2:1 were tested and compared. This study demonstrates that Nb2CTx-Ag composite shows higher antibacterial properties than Nb2CTx and delaminated Nb2CTx MXene and could reach an antibacterial activity of 98.5 % for S. aureus and 100 % for E. coli.

Isocyanide Ligation Enables Electrochemical Ammonia Formation in a Synthetic Cycle for N2 Fixation.

Transition-metal-mediated splitting of N2 to form metal nitride complexes could constitute a key step in electrocatalytic nitrogen fixation, if these nitrides can be electrochemically reduced to ammonia under mild conditions. The envisioned nitrogen fixation cycle involves several steps: N2 binding to form a dinuclear end-on bridging complex with appropriate electronic structure to cleave the N2 bridge followed by proton/electron transfer to release ammonia and bind another molecule of N2. The nitride reduction and N2 splitting steps in this cycle have differing electronic demands that a catalyst must satisfy. Rhenium systems have had limited success in meeting these demands, and studying them offers an opportunity to learn strategies for modulating reactivity. Here, we report a rhenium system in which the pincer supporting ligand is supplemented by an isocyanide ligand that can accept electron density, facilitating reduction and enabling the protonation/reduction of the nitride to ammonia under mild electrochemical conditions. The incorporation of isocyanide raises the N-H bond dissociation free energy of the first N-H bond by 10 kcal/mol, breaking the usual compensation between pKa and redox potential; this is attributed to the separation of the protonation site (nitride) and the reduction site (delocalized between Re and isocyanide). Ammonia evolution is accompanied by formation of a terminal N2 complex, which can be oxidized to yield bridging N2 complexes including a rare mixed-valent complex. These rhenium species define the steps in a synthetic cycle that converts N2 to NH3 through an electrochemical N2 splitting pathway, and show the utility of a second, tunable supporting ligand for enhancing nitride reactivity.

Biosensors for measuring nitric oxide NO levels in biosubstrates: a systematic analysis

Nitric oxide NO is a signaling molecule involved in numerous physical and pathological processes in biological systems. Highly sensitive sensor materials for measuring NO amounts in vivo in exhaled air and in body fluids (saliva, blood, urine) can be a useful tool in diagnostics and management of patients with bronchopulmonary, cardiovascular, neurological and tumor diseases. Several approaches to measuring NO in biosubstrates (including exhaled air) have been developed: fluorescence/chemiluminescence, electron spin resonance, electrochemical/amperometric (organic and inorganic) and enzymatic/protein sensors. Semiconductors, transition metal nitrides, phthalocyanine complexes, porphyrin and cobalamin derivatives with metals can serve as materials for NO sensors. Creating sensor materials based on vitamin B12 derivatives is an urgent research task in biomedicine. The article systematizes information on using various compounds as materials for NO-sensitive and selective sensors to measure/evaluate NO levels in various biosubstrates.

Engineered Nickel-Iron Nitride Electrocatalyst for Industrial-Scale Seawater Hydrogen Production.

Seawater electrolysis under alkaline conditions is a crucial technology for sustainable hydrogen production. However, achieving the long-term stability of the electrocatalyst remains a significant challenge. In this study, it is demonstrated that surface reconstruction of a transition metal nitride (TMN) can be used to develop a highly stable oxygen evolution reaction (OER) electrocatalyst. Rapid introduction of phosphate groups (PO4 3-) accelerates the in situ surface reconstruction of Ni3FeN, generating a catalyst, with a conductive nitride core and Cl--resistant hydroxide shell that demonstrates outstanding performance, maintaining stability for over 2500 h at 1 A cm-2 current density in alkaline seawater. In situ characterization and density functional theory (DFT) calculations reveal the dynamic evolution of active sites, providing insights into the mechanisms driving long-term stability. This work not only introduces an efficient approach to TMN-based catalyst design but also advances the development of durable electrocatalysts for industrial-scale seawater hydrogen production.

Physical properties and thermal stability of zirconium platinum nitride thin films

Ternary transition metal nitrides (TMNs) promise to significantly expand the material design space by opening new functionality and enhancing existing properties. However, most systems have only been investigated computationally, and limited understanding of their stabilizing mechanisms restricts translation to experimental synthesis. To better elucidate key factors in designing ternary TMNs, we experimentally fabricate and analyze the physical properties of the ternary Zr–Pt–N system. Structural analysis and density functional theory modeling demonstrate that Pt substitutes nitrogen on the nonmetallic sublattice, which destabilizes the rock salt structure and forms a complex cubic phase. We also show insolubility of Pt in the Zr–Pt–N at 45 at. % with the formation of a secondary Pt-rich phase. The measured reduced plasma frequency, decrease in resistivity, and decrease in hardness reflect a dominance of metallic behavior in bonding. Additionally, we observe the exsolution of Pt nano precipitates from the Zr–Pt–N films upon annealing as well as degradation in the nitridic film's thermal stability. Even at low concentrations (1%), Pt facilitates a solid reaction with the Si substrate that is otherwise inaccessible in ZrN films.