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This paper presents experimental results concerning the one-step preparation of cast divanadium nitride and aluminum oxynitride (AlON) by high-temperature synthesis under 5 MPa of N 2 from green mixtures containing vanadium oxide, aluminum, and aluminum nitride. It was shown that the mixtures with a wide range of component ratios are capable to burn with the temperature exceeding the melting point of the final products, divanadium nitride and aluminum oxynitride, that makes it possible to obtain them in the form of a melt with subsequent separation of vanadium nitride (lower ingot) and aluminum oxynitride (upper ingot). The resulting products had no cohesion and were easily separated from each other. Variation in the content of aluminum nitride in the charge markedly affected the synthesis process, phase composition, and microstructure of the target products. The content of excess aluminum nitride in the starting mixture α = 10% was found to be optimum on a yield/composition of the target products. [ABSTRACT FROM AUTHOR]

Abstract Vanadium nitride (VN) is a transition-metal nitride with remarkable properties that have prompted extensive experimental and theoretical investigations in recent years. However, there is a current paucity of experimental research investigating the temperature-dependent electronic structure of single-crystalline VN. In this study, high-quality VN(111) films were successfully synthesized on $$\alpha$$ α -Al $$_2$$ 2 O $$_3$$ 3 (0001) substrates using magnetron sputtering. The crystal and electronic structures of the VN films were characterized by a combination of high-resolution X-ray diffraction, low-energy electron diffraction, resonant soft X-ray absorption spectroscopy, and ultraviolet photoelectron spectroscopy. The electrical transport measurements indicate that the superconducting critical temperature of the VN films is around 8.1 K. Intriguingly, the temperature-dependent photoelectron spectroscopy measurements demonstrate a weak temperature dependence in the electronic structure of the VN films, which is significant for understanding the ground state of VN compounds.

Lithium–sulfur batteries (LSBs) are recognized as among the best potential alternative battery systems to lithium-ion batteries and have been widely investigated. However, the shuttle effect has severely restricted the advancement in their practical applications. Here, we prepare vanadium nitride (VN) nanoparticles grown in situ on a nitrogen-doped carbon skeleton (denoted as VN@NC) derived from the MAX phase and use it as separator modification materials for LSBs to suppress the shuttle effect and optimize electrochemical performance. Thanks to the outstanding catalytic performance of VN and the superior electrical conductivity of carbon skeleton derived from MAX, the synergistic effect between the two accelerates the kinetics of both lithium polysulfides (LiPSs) to Li2S and the reverse reaction, effectively suppresses the shuttle effect, and increases cathode sulfur availability, significantly enhancing the electrochemical performance of LSBs. LSBs constructed with VN@NC-modified separators achieve outstanding rate performance and cycle stability. With a capacity of 560 mAh g−1 at 4 C, it exhibits enhanced structural and chemical stability. At 1 C, the device has an incipient capacity of 1052.4 mAh g−1, and the degradation rate averaged only 0.085% over 400cycles. Meanwhile, the LSBs also show larger capacities and good cycling stability at a low electrolyte/sulfur ratio and high surface-loaded sulfur conditions. Thus, a facile and efficient way of preparing modified materials for separators is provided to realize high-performance LSBs. [ABSTRACT FROM AUTHOR]

This comprehensive chemistry experiment utilizes vanadium trichloride and hexamethylenetetramine as precursors to synthesize a heterostructured composite material consisting of nano-scaled vanadium nitride particles embedded in nitrogen-doped carbon sheets through template-assisted heat treatment and nitridation methods. Furthermore, the electrocatalytic nitrogen reduction performance of the composite material is thoroughly examined. The experimental procedure encompasses interdisciplinary knowledge and practical skills in inorganic chemistry, physical chemistry, and analytical chemistry, with a focus on cutting-edge scientific research. By stimulating students' interest in learning and enhancing their application abilities, this experiment aims to cultivate students' disciplinary literacy, research innovation capabilities, and sense of social responsibility. [ABSTRACT FROM AUTHOR]

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Vanadium nitride (VN) is a transition-metal nitride with remarkable properties that have prompted extensive experimental and theoretical investigations in recent years. However, there is a current paucity of experimental research investigating the temperature-dependent electronic structure of single-crystalline VN. In this study, high-quality VN(111) films were successfully synthesized on α -Al 2 O 3 (0001) substrates using magnetron sputtering. The crystal and electronic structures of the VN films were characterized by a combination of high-resolution X-ray diffraction, low-energy electron diffraction, resonant soft X-ray absorption spectroscopy, and ultraviolet photoelectron spectroscopy. The electrical transport measurements indicate that the superconducting critical temperature of the VN films is around 8.1 K. Intriguingly, the temperature-dependent photoelectron spectroscopy measurements demonstrate a weak temperature dependence in the electronic structure of the VN films, which is significant for understanding the ground state of VN compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-rate solid-state supercapacitors were assembled by the integrated Fe-NiCoP/CC cathode and VN/CNT/CC anode respectively. • The doped Fe ions in NiCoP significantly improve the electronic conductivity and adsorption capacity of OH−. • The integrated electrodes and solid-state supercapacitors show excellent electrochemical performance and EMI shielding. The development of flexible and wearable electronics subjects to the limited energy density and accompanying electromagnetic pollution. With a high theoretical specific capacity, nickel–cobalt bimetallic phosphide (NiCoP) is considered to be potential cathode materials for supercapacitor. However, the pristine NiCoP fails to display excellent electrochemical performance due to its inferior rate performance and cycling stability. Herein, we design Fe doped NiCoP nanowire arrays on carbon cloth (Fe-NiCoP/CC) as the cathode for supercapacitors. The introduced Fe doping enable to increase in the electronic conductivity and enhance the adsorption of OH−, supported by the density functional theory (DFT) analysis. As a result, Fe-NiCoP/CC electrode displays a high areal capacity of 3.18 F cm−2 at 1 mA cm−2, superb rate capability (86.3 % capacity retention at 20 mA cm−2) and outstanding structure stability, superior to the NiCo/CC, FeNiCo/CC, and NiCoP/CC counterparts. Moreover, the assembled Fe-NiCoP/CC||VN/CNT/CC hybrid supercapacitor (HSC) device delivers a high energy density of 176.9 μWh cm−2 at the power density of 750 μW cm−2. More importantly, the designed electrodes and assembled HSC device exhibits excellent electromagnetic interference (EMI) shielding performance. This design concept presented in this paper can provide insights into the construction of multifunctional and high-performance flexible electronic devices. [ABSTRACT FROM AUTHOR]

Vanadium sesquioxide/vanadium nitride nanoparticles were prepared in carbon fibers by electrospinning, followed by carbonization. Polyacrylonitrile was used as the carbon precursor, poly-(methyl methacrylate) as the porogen, and V2O5 nanowires as the vanadium source. During the high temperature carbonization, V2O5 was reduced in situ by carbon and converted into V2O3 and further transformed into VN by NH3 released from polyacrylonitrile. The composite was used as electrodes and fabricated into a symmetric coin cell-type supercapacitor using 1 M lithium bis-(trifluoromethanesulfonyl)-imide in propylene carbonate as the electrolyte. The resulting supercapacitor showed a specific capacitance of 369 F g–1 at 5 mV/s, an energy density of 107 Wh kg–1 at 0.05 A g–1, and a high power density of 5154 W kg–1 at 5 A g–1. [ABSTRACT FROM AUTHOR]

Ceramic nitride samples of tailored composition and shape have been prepared by controlled nitridation of Ti–V metal pairs. We have obtained kinetic and current–voltage curves for the interaction of the Ti–V metal pairs with nitrogen. In different parts of the metal pairs, the nitridation process follows different mechanisms. In the case of the pure metals, the formation of nearly stoichiometric ceramics involves the formation of three- and two-layer graded structures. Nitridation of the junction region, containing a Ti–V solid solution, is determined by the chemical affinity of titanium and vanadium for nitrogen. The formation of titanium nitride leads to decomposition of the Ti–V solid solution in the junction and vanadium metal separation on grain boundaries. The rate of vanadium nitridation increases as the titanium content of the solid solution decreases. The thermoelectric voltage of the Ti–V system in the temperature range from –195.7 to +550°C has been evaluated as a function of the degree of nitridation. The thermoelectric voltage and Seebeck coefficient of metal–ceramic and ceramic structures have been determined as functions of temperature. Characteristically, the thermoelectric voltage of all the nitrided pairs rises monotonically over the entire temperature range studied. Nitrided titanium–vanadium pairs with tailored composition can be used as ceramic thermoelectric converters. [ABSTRACT FROM AUTHOR]

An advanced Fe 2 N@Fe 3 O 4 /VN heterostructure with dual interfaces and dual conductive layer confinements is rationally constructed to improve the distribution and alleviate the volume expansion as well as increase the electron conductivity of Fe 3 O 4. Benefiting from these merits, it presents significantly improved rate performance and cycling stability. [Display omitted] • A Fe 2 N@Fe 3 O 4 /VN heterostructure with dual interfaces and confinements is constructed. • This strategy addresses volume expansion, lower conductivity, and agglomeration of Fe 3 O 4 nanoparticles. • The composite exhibits greatly improved rate performance and cycling stability. Ferroferric oxide (Fe 3 O 4) as an anode material of lithium-ion battery has been widely investigated due to its high theoretical capacity, environmental friendliness, natural abundance, and low cost. However, it suffers from severe aggregation and volume expansion during energy storage. Herein, we rationally construct an advanced Fe 2 N@Fe 3 O 4 /VN heterostructure via a hydrothermal and followed nitridation process, where the wrapping of conductive Fe 2 N on the surface of Fe 3 O 4 effectively improves the electron conductivity and alleviates the volume expansion, and VN inhibits the agglomeration of Fe 2 N@Fe 3 O 4. Benefiting from the dual conductive confinements and promoted interfacial charge transfer, the Fe 2 N@Fe 3 O 4 /VN heterojunction exhibits excellent rate capability and cycling stability. It possesses the highest reversible capacity of 420.8 mAh g−1 at 1 A g−1 after 600 cycles, which is three times that of Fe 3 O 4. Furthermore, a full cell based on a Fe 2 N@Fe 3 O 4 /VN anode and a LiFePO 4 cathode delivers considerable electrochemical performance. This work demonstrates that Fe 2 N@Fe 3 O 4 /VN is a potential anode material and provides a model in constructing other high-performance electrode materials. [ABSTRACT FROM AUTHOR]

In this study, nanostructured coatings of VN2/Fe3N/Fe4N are synthesized by Plasma Deposition (CCPD) using a vanadium cathodic cage and subject to cathodic and floating potential treatments. Microstructural and mechanical properties of coated SAE 1080 steel samples are investigated using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Vickers microhardness (HV), and surface roughness analysis. The coating produced under cathodic potential treatment exhibited a nitride-based microstructure (VN2, Fe3N, Fe4N), with surface morphology consisting of clusters of granular structures with varied particle sizes. The coating produced under floating potential predominantly exhibited the iron nitride phase (Fe3N) with a morphology composed of uniformly sized grains. Microhardness testing showed that both layers exhibited more excellent plastic deformation resistance than the substrate. Roughness measurements confirmed a more organized microstructure profile for the sample treated under floating potential. This study demonstrates that the CCPD-produced cathodic potential coating can be utilized in tribological applications.

Abstract Vanadium nitride (VN) electrode displays high‐rate, pseudocapacitive responses in aqueous electrolytes, however, it remains largely unclear in nonaqueous, Na+‐based electrolytes. The traditional view supposes a conversion‐type mechanism for Na+ storage in VN anodes but does not explain the phenomena of their size‐dependent specific capacities and underlying causes of pseudocapacitive charge storage behaviors. Herein, we insightfully reveal the VN anode exhibits a surface‐redox pseudocapacitive mechanism in nonaqueous, Na+‐based electrolytes, as demonstrated by kinetics analysis, experimental observations, and first‐principles calculations. Through ex situ X‐ray photoelectron spectroscopy and semiquantitative analyses, the Na+ storage is characterized by redox reactions occurring with the V5+/V4+ to V3+ at the surface of VN particles, which is different from the well‐known conversion reaction mechanism. The pseudocapacitive performance is enhanced through nanoarchitecture design via oxidized vanadium states at the surface. The optimized VN‐10 nm anode delivers a sodium‐ion storage capability of 106 mAh g−1 at the high specific current of 20 A g−1, and excellent cycling performance of 5000 cycles with negligible capacity losses. This work demonstrates the emerging opportunities of utilizing pseudocapacitive charge storage for realizing high‐rate sodium‐ion storage applications.

The escalating demand for sustainable and high-performance energy storage systems has led to the exploration of alternative battery technologies for lithium-ion batteries. Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have emerged as promising candidates because of their abundant Na/K resources, inexpensive costs, and similar chemistries to lithium-ion batteries. However, inherent challenges, such as large ionic radii, sluggish kinetics, and serious volume expansion, necessitate the development of robust and efficient anode materials for SIBs and PIBs. Vanadium nitride has attracted increasing attention as a viable anode due to its high electronic conductivity and potential capacity. In this study, we report on a flexible electrode for SIBs and PIBs that creates binder-free anodes by synthesizing vanadium nitride nanoparticles grown directly on carbon fiber cloths (VN/CFC). The unique architecture and binder-free nature of this anode ensure a robust electrode–electrolyte interface and enhance its electron/ion transport kinetics. The results demonstrate that the material exhibits an outstanding specific discharge capacity of 227 mAh g−1 after undergoing 1000 cycles at a current density of 2 A g−1 for SIBs. An electrochemical analysis indicated that the excellent performance of the material is attributed to the bind-free structure of carbon fiber cloth and the fast kinetics of surface pseudo-capacitive contribution. Furthermore, the material continues to demonstrate an impressive performance, even for PIBs, with a specific discharge capacity of 125 mAh g−1 after 1000 cycles at a current density of 1 A g−1. This study provides a new perspective for designing and developing advanced binder-free anodes for the storage of sodium and potassium ions, paving the way for high-performance energy storage applications. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries (LSBs) are recognized as among the best potential alternative battery systems to lithium-ion batteries and have been widely investigated. However, the shuttle effect has severely restricted the advancement in their practical applications. Here, we prepare vanadium nitride (VN) nanoparticles grown in situ on a nitrogen-doped carbon skeleton (denoted as VN@NC) derived from the MAX phase and use it as separator modification materials for LSBs to suppress the shuttle effect and optimize electrochemical performance. Thanks to the outstanding catalytic performance of VN and the superior electrical conductivity of carbon skeleton derived from MAX, the synergistic effect between the two accelerates the kinetics of both lithium polysulfides (LiPSs) to Li2S and the reverse reaction, effectively suppresses the shuttle effect, and increases cathode sulfur availability, significantly enhancing the electrochemical performance of LSBs. LSBs constructed with VN@NC-modified separators achieve outstanding rate performance and cycle stability. With a capacity of 560 mAh g−1 at 4 C, it exhibits enhanced structural and chemical stability. At 1 C, the device has an incipient capacity of 1052.4 mAh g−1, and the degradation rate averaged only 0.085% over 400cycles. Meanwhile, the LSBs also show larger capacities and good cycling stability at a low electrolyte/sulfur ratio and high surface-loaded sulfur conditions. Thus, a facile and efficient way of preparing modified materials for separators is provided to realize high-performance LSBs.

Vanadium nitride (VN) thin films have been deposited on silicon wafer substrates by reactive DC magnetron sputtering with varied nitrogen (N2) flow rates from 5.0 to 8.0 sccm without substrate heating. The crystallinity, morphology, and optical properties of the prepared VN films were investigated by gracing-incidence X-ray diffraction (GIXRD), field emission scanning electron microscope (FE-SEM), and UV-Vis-NIR spectrophotometer, respectively. The GIXRD pattern shows that the crystal structure of the films is consistent with the face-centered cubic VN structure. An increase in N2 led to a decrease in film thickness and sheet resistance. On the contrary, the reflectance percentage tends to increase with the increase of N2 flow rate. [Copyright information to be updated in the production process]. [ABSTRACT FROM AUTHOR]

The optimized VN-2 composite exhibits an impressive high-rate capacity and ultra-long lifespan for zinc-ion batteries in all-climate conditions (-15–50 °C) achieved by the Zn2+ intercalation and conversion storage mechanism. [Display omitted] • The VN shows a high capacity of 272 mAh g−1 after 7000 cycles at 5 A g−1. • The ex-situ results disclose the Zn2+ intercalation and conversion storage mechanism. • It shows remarkable performance for AZIBs in all-climate conditions (-15–50 °C). Rechargeable aqueous zinc-ion batteries have great promise for becoming next-generation storage systems, although the irreversible intercalation of Zn2+ and sluggish reaction kinetics impede their wide application. Therefore, it is urgent to develop highly reversible zinc-ion batteries. In this work, we modulate the morphology of vanadium nitride (VN) with different molar amounts of cetyltrimethylammonium bromide (CTAB). The optimal electrode has porous architecture and excellent electrical conductivity, which can alleviate volume expansion/contraction and allow for fast ion transmission during the Zn2+ storage process. Furthermore, the CTAB-modified VN cathode undergoes a phase transition that provides a better framework for vanadium oxide (VO x). With the same mass of VN and VO x , VN provides more active material after phase conversion due to the molar mass of the N atom being less than that of the O atom, thus increasing the capacity. As expected, the cathode displays an excellent electrochemical performance of 272 mAh g−1 at 5 A g−1, high cycling stability up to 7000 cycles, and excellent performance over a wide temperature range. This discovery creates new possibilities for the development of high-performance multivalent ion aqueous cathodes with rapid reaction mechanisms. [ABSTRACT FROM AUTHOR]

Vanadium nitride film made using a thin film deposition technique is a promising electrode material for micro‐supercapacitor applications owing to its high electrical conductivity and high volumetric and surface capacitance values in aqueous electrolyte. Nevertheless, the cycling stability has to be improved to deliver good capacitance during a large number of cycles. Here, it is shown that vanadium nitride films made by a magnetron sputtering deposition method exhibit remarkable cycling stability (high capacitance retention value after 150 000 cycles), ultra‐high rate capability (75% of the initial capacitance at 1.6 V s−1), while providing high surface capacitance values (≈1.4 F cm−2) and very low ageing of the VN electrodes (no loss of performance after 13 months). Additionally, new findings regarding the location of vanadium oxides species responsible for the charge storage mechanism in pseudocapacitive VN films are revealed by transmission electron microscopy electron energy‐loss spectroscopy analyses at the nanoscale. [ABSTRACT FROM AUTHOR]

In this study, synchrotron radiation X-ray diffraction is used to study the equation of state of vanadium nitride in a diamond anvil cell at room temperature. Experimental results reveal the high stability of the cubic structure up to 76 GPa pressure. In addition, the bulk modulus of vanadium nitride derived from XRD data is K0 = 328.4(2.8) GPa with K0′ = 5.86(0.14). Finally, the high pressure compression behavior is investigated to 80 GPa using density functional theory of first-principle calculations, and the obtained bulk elastic modulus is 316 GPa. Vanadium nitride is not magnetic in the whole pressure range and is metallic. Highlights • We have investigated the equation of state of VN under high pressure with silicone oil as the pressure transmitting medium to 76 GPa. • It was found that the face-centred cubic structure of VN maintains the maximum pressure of 76 GPa. • We have carried out first-principles calculations and obtained the equation of state, band structure, and electronic density of state of VN to 80 GPa. [ABSTRACT FROM AUTHOR]

The issues of inadequate cycle stability and energy density for aqueous zinc‐ion batteries (ZIBs) can be partly addressed by controlling cathode dissolution and structural deterioration and improving electronic conductivity and reaction kinetics. Herein, vanadium nitride embedded nitrogen‐doped carbon nanofiber (VN/N‐CNFs) composites with 3D self‐supported skeletons and hierarchical structures are developed by an electrospinning technique and thermal treatments. The introduction of vanadium‐based metal organic frameworks (V‐MOFs) contributes to in situ hierarchical growth of whisker‐like secondary structures and homogeneous distribution of 0D active VN nanograins into both trunk nanofibers and branched nano‐whiskers. The protective and conductive carbon matrix derived from functional V‐MOFs and electrospun nanofibers not only prevents the self‐aggregation of highly‐active 0D nanograins, but also provides encapsulating shells to suppress the vanadium dissolution by controlling the direct contact with aqueous electrolytes. Furthermore, the flexible and free‐standing 3D electrospun VN/N‐CNFs skeletons contribute high structural integrity for the aqueous ZIBs, exhibiting an ultra‐long cycle lifespan with reversible capacity of 482 mAh g−1 after cycling at 50 A g−1 for 30,000 cycles and a super‐high rate capability with discharge capacity of 297 mAh g−1 at high rate of 100 A g−1. This research sheds light upon a pathway toward designing superior ZIBs. [ABSTRACT FROM AUTHOR]

The present work evaluates the nitriding and deposition of niobium and vanadium films using the cathode cage technique and its influence on the formation of a double film generated from these two sequential treatments (duplex film) on AISI D2 steel substrates. The element niobium has attracted research because Brazil has the most significant deposits of this ore in the world, and the properties of this element are important for several applications. For example, niobium nitride has excellent properties such as high hardness and toughness, thermodynamic stability, and wear and corrosion resistance. Another nitride film that stands out due to its excellent properties is vanadium nitride (VN), which presents better corrosion resistance and reduced friction coefficient at high temperatures and favors high-speed machining. This work evaluated the wear resistance, microstructure, adhesion and composition of the deposited layer, and microhardness. [ABSTRACT FROM AUTHOR]

Transition metals and their compounds supported on carbon materials are widely used as cathodes for lithium‐sulfur batteries. Vanadium nitride is considered to be a promising cathode because of its good adsorption capacity for lithium polysulfides and high catalytic activity, but in practice it usually shows insufficient electrical conductivity and low electrocatalytic activity due to particles agglomeration. In this study, highly dispersed vanadium nitride supported on porous nitrogen‐doped carbon was prepared via one‐pot pyrolysis in a molten salt medium. Physical characterization revealed VN particles with a uniform size distribution of ca. 10 nm well dispersed on the carbon surface. When used as a cathode for Li−S battery, the material delivered a specific discharge capacity of 1050 mAh g−1 at 0.2 C and good rate performance. During the stability test over 500 continuous cycles, the average decay rate was 0.059 % per cycle. The study demonstrates prospective application of the newly developed electrocatalytic material as a cathode in lithium‐sulfur batteries. [ABSTRACT FROM AUTHOR]

The term "silver-doped vanadium titanium nitride" refers to a class of composite biomaterial that combines the characteristics of vanadium titanium nitride with silver's antibacterial and bioactive capabilities. Using the physical vapor deposition (PVD) technique, the coating was applied by first depositing a single layer of Titanium on a titanium substrate, followed by a layer of TiVN(Ag), with fixed power for the Titanium (450W) and vanadium (350W), and variable power for the silver (25–100W). Atomic force microscopy (AFM) was used to evaluate surface morphology, transmission electron microscopy (TEM) was used to evaluate cross-sectional microstructural analysis of coatings, X-ray diffraction (XRD) was used to evaluate the phase formation of the coating, X-ray photoemission spectroscopy (XPS) was used to evaluate composition and atomic bonding, and finally, the biocompatibility test was conducted individually to evaluate the viability of MG-63 cells. Our results showed that the fluctuation of the silver concentration in the system impacts the microstructural and biological characteristics of the coating. The best balance between cell viability and microstructure was obtained using a sample of TiVN(Ag) and 50W of electricity. [Display omitted] • Silver titanium vaadium nitride (TiVN–Ag) coatings were successfully fabricated using magnetron sputtering. • The incorporation of silver atoms into TiVN coatings influenced their structural and chemical properties. • Variations in silver power during deposition significantly impacted the crystalline orientation of TiVN–Ag coatings. • Fluorescence microscopy revealed distinct cell responses to TiVN–Ag coatings with varying silver. [ABSTRACT FROM AUTHOR]

Transition metal nitrides present superior electrocatalytic activities on the air electrode for fuel cells or metal-air batteries. Despite that, the weak intrinsic activity and ease of aggregation have hampered their catalytic kinetic properties and practical application. Herein, vanadium nitride (VN) particles of different sizes, micron to molecular level, have been fabricated using a facile, in-situ urea-nitridation method, and embedded in an N-doped graphitic carbon aerogel electrocatalyst (VN@CA), the doped material serving as an oxidation catalyst. Having a balance of atomic-level dispersed VN clusters and a high active site density, the obtained VN@CA catalytic material exhibits enhanced catalytic efficiency for the oxygen reduction reaction (ORR), the values of onset and half-wave voltages were measured to be 0.97 V and 0.90 V, respectively, compared to Pt/C (which had voltages of 0.95 V and 0.87 V). Furthermore, the assembled Zn-air battery using VN@CA as catalyst exhibits a high-power density of 176 mW cm−2, a substantial specific discharge capacity of 851 mAh g Zn −1 at 20 mA cm−2, a narrow gap between charging and discharging voltages (0.73 V at 50 mA cm−2), and an excellent charge-discharge cycling stability, exceeding 270 cycles with a 66 % round-trip efficiency. This work confirms that the particle size and the density both are responsible for the enhanced electrochemical activity. • Vanadium nitride (VN) particles with the sizes from micron to molecular level, have been fabricated using a facile method. • The active sites VN nanoparticles anchored on an N-doped graphitic carbon aerogel with a pore volume of 1.55 cm3 g−1. • The size evolution mechanism of VN nanoparticles is investigated. • The VN@CA catalyst as the air cathode in Zn-air batteries (ZABs) shows superior catalytic activities. [ABSTRACT FROM AUTHOR]

Li-S batteries suffered from the severe "shuttle effect", resulting in poor conversion kinetics and limited life-span. This work proposed an electrochemical active porous architecture (EPA) interlayer to regulate the migration of ions and electrons, and highlights the importance of porous structure design and chemical modification of functional interlayer for reliable lithium–sulfur batteries. [Display omitted] • An electrochemical active porous architecture (EPA) is synthesized through hydrothermal reaction and heat treatment (550 °C) under ammonia atmosphere. • The EPA displays a sponge-like porous morphology with an interconnected porous structure and decorated numerous VN nanoparticles, and achieves strong chemical interaction toward lithium polysulfides and enhanced electrolyte diffusion. • The liquid–solid transformation kinetics of polysulfides can be accelerated in the EPA + TMM separator, thereby further achieving a dense and smooth Li deposition morphology. • Low polarization, high initial discharge capacity, good rate capabilities, and excellent cycling performance are achieved. Although lithium–sulfur batteries have excellent theoretical specific capacity (1675 mAh g−1) and high energy density (2600 wh kg−1), their practical application is hampered by the severe "shuttle effect" of polysulfides in ether-based electrolytes. Soluble polysulfides can migrate across separator and react with lithium metal, resulting in a rapid capacity decay. In this study, we proposed an electrochemical active porous architecture (EPA) interlayer to address this tricky issue. Firstly, the porous architecture guarantees efficient electrolyte diffusion. Additionally, the catalytic vanadium nitride particles within the conductive skeleton can capture soluble polysulfides, accelerate their redox reaction, and suppress the "shuttle effect", thereby further restraining the parasitic reaction between lithium metal anode and polysulfides. Therefore, integrating the EPA interlayer in the battery enables an initial capability of 1465.8 mAh g−1 at 0.1C and delivers a good rate performance at 2.0C (668.0 mAh g−1). The battery achieves an average capacity of 796.7 mAh g−1 within the first 500 cycles under 0.5C, with a high average Coulombic efficiency of 99.8 %, indicating the practical potential of EPA interlayer design for application in reliable lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

In recent years, heterojunction has attracted widespread attention as an anode for sodium-ion batteries since they can effectively optimize the materials' rate performance and cycling stability. However, the advantage is choked by multi-element composition and stepwise synthesis process. Herein, cobalt sulfide (Co 9 S 8 /CoS) homologous heterojunction deposited at vanadium nitride/carbon nanofibers is synthesized as an excellent anode for high-performance sodium-ion batteries in one step by employing the "3 d -orbital electron complementary effect" combined with high-temperature heat-treatment technology. The Co 9 S 8 /CoS homologous heterojunction successfully overcomes the inherent drawback of Co 9 S 8 and possesses an ultrafast charging/discharging process, outstanding reversible specific capacity, and remarkable rate capability. A systematic study reveals that vanadium nitride is a key trigger for forming Co 9 S 8 /CoS heterojunction. When used as anode materials for sodium-ion batteries, it reaches a high specific capacity of 353.0 mAh/g at a current density of 10 A/g (615.8 mAh/g at a current density of 0.05 A/g) due to the presence of heterointerface. Theoretical calculations show that the construction of the heterostructure enhances the sodium-ion storage capacity and storage kinetics compared with pristine Co 9 S 8. This discovery opens an interesting strategy for constructing homogeneous heterojunctions and broadens the horizons for designing energy storage and conversion materials. The Co 9 S 8 /CoS homologous heterojunction deposited at vanadium nitride /carbon nanofibers is constructed by combining the "3 d -orbital electron complementation effect" of vanadium nitride and the Co atom with high-temperature heat-treatment technology to achieve ultrafast and high-capacity sodium-ion storage. [Display omitted] [ABSTRACT FROM AUTHOR]

The escalating demand for sustainable and high-performance energy storage systems has led to the exploration of alternative battery technologies for lithium-ion batteries. Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have emerged as promising candidates because of their abundant Na/K resources, inexpensive costs, and similar chemistries to lithium-ion batteries. However, inherent challenges, such as large ionic radii, sluggish kinetics, and serious volume expansion, necessitate the development of robust and efficient anode materials for SIBs and PIBs. Vanadium nitride has attracted increasing attention as a viable anode due to its high electronic conductivity and potential capacity. In this study, we report on a flexible electrode for SIBs and PIBs that creates binder-free anodes by synthesizing vanadium nitride nanoparticles grown directly on carbon fiber cloths (VN/CFC). The unique architecture and binder-free nature of this anode ensure a robust electrode–electrolyte interface and enhance its electron/ion transport kinetics. The results demonstrate that the material exhibits an outstanding specific discharge capacity of 227 mAh g−1 after undergoing 1000 cycles at a current density of 2 A g−1 for SIBs. An electrochemical analysis indicated that the excellent performance of the material is attributed to the bind-free structure of carbon fiber cloth and the fast kinetics of surface pseudo-capacitive contribution. Furthermore, the material continues to demonstrate an impressive performance, even for PIBs, with a specific discharge capacity of 125 mAh g−1 after 1000 cycles at a current density of 1 A g−1. This study provides a new perspective for designing and developing advanced binder-free anodes for the storage of sodium and potassium ions, paving the way for high-performance energy storage applications.

The precipitation of V and Cu in the powder forged connecting rods of Fe-V-Cu-C alloy, were studied by atom probe tomography (APT). The purpose of alloying with V was to further improve the mechanical properties of the existing powder forged materials based on Fe-Cu-C. In this study, materials tested at room temperature and 120°C were investigated. It was found that Cu was unevenly distributed on a micrometer scale. The local Cu content affected the Cu precipitation; a higher Cu content resulted in a higher volume fraction of precipitates. The V was found to form very small nitrides. The N presumably originates from the sintering process. The vanadium nitrides act as nucleation points for the Cu precipitates during cooling of the material during fabrication. APT analysis of the deformed material close to the fracture surface of the tensile test samples showed a similar volume fraction of Cu precipitates, but statistical analysis of the data indicates that both Cu and VN precipitates are more diffuse than in the undeformed material. [ABSTRACT FROM AUTHOR]

[Display omitted] Porous carbon-supported transition metals and their compounds have attracted much attention as sulfur host materials for cathodes of lithium-sulfur batteries, due to their high chemisorption capacity and ability to catalyze the conversion of polysulfides. However, actual activity of these materials is not very high because of low specific surface areas of transition metal compounds synthesized at high temperatures. In this study, ultra-fine vanadium nitride particles with an average particle size of ca. 4 nm (VN/M/NC) are successfully grown on the surface of nitrogen-doped three-dimensional carbon using sp2 nitrogen atoms, resulting from melamine pyrolysis in the presence of ammonium metavanadate, as anchor points to lock vanadium atoms in the VN/M/NC material. When used as a cathode for lithium-sulfur battery, VN/M/NC demonstrates initial discharge specific capacity of 1080 mAh g−1 at 0.2 C, and retains a discharge capacity of 475 mAh g−1 at a high rate of 2 C. With capacity attenuation of only 0.037% per cycle after 500 cycles at 1 C, the newly obtained VN/M/NC can be a promising cathode material for lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

Developing a high‐rate and stable battery‐type anode to match the capacitor‐type cathode is a critical issue for potassium ion capacitors (PICs). Surface‐redox pseudocapacitive materials can meet this demand due to their fast surface Faradaic reaction kinetics and superior structure stability during charging–discharging. Herein, a free‐standing anode by growing VN particle‐composed nanosheets on carbon fibers (VN@CFs) is developed. The VN@CFs is endowed with high reversible capacity of 245.8 mA h g–1 at 0.05 A g–1, high rate performance of 102.7 mA h g–1 at 6.0 A g–1, and long‐term stability. Based on the in situ XRD, ex situ XPS and TEM characterizations, and density functional theory calculations, it is proved that the potassium storage of VN derives from a surface‐redox pseudocapacitive mechanism between VN and K+, rather than an intercalation or conversion reaction. As expected, the as‐assembled PICs based on the VN@CFs anode show an ultrahigh power output of 10.9 kW kg–1 when keeping an energy density of 49.2 Wh kg–1 and excellent capacity retention of 86.8% after 15000 cycles. [ABSTRACT FROM AUTHOR]

Interface engineering is deemed as an effective approach to optimize the electronic structure of catalytically active sites in electrocatalysts for boosted hydrogen evolution reaction (HER). Herein, a novel ultrasmall VN/Co heterostructure anchored in N-doped graphitized nanocarbons (VN/Co@GNC) is successfully synthesized by a simple calcination protocol. Benefiting from the abundant reactive sites on the interface of ultrasmall heterostructure, enhanced N active sites of VN coupled with Co nanoparticles, as well as excellent conductivity of N-doped graphitized nanocarbons as the scaffold, the resulting VN/Co@GNC material exhibits outstanding electrocatalytic HER performance, delivering the current density of 10 mA/cm2 at a quite low overpotential of 155 mV without iR-compensation, and retaining the catalytic durability for at least 565 h (∼23.5 days) in 1 M KOH solution. The superior catalytic activity and ultrastability of VN/Co@GNC electrocatalyst lay a solid foundation for its commercial applications toward the hydrogen fuel production.

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Exploring earth-abundant electrocatalysts with high efficiency and stability for oxygen evolution reaction (OER) is vital to hydrogen production technology, which especially can work well at higher current density. Herein, we report a facile method for the in situ growth of vertical nanoarray vanadium nitride and carbon nanotube hybrid materials on iron foam (labeled as VN/CNT/IF). The obtained catalyst exhibits good electrocatalytic activity and stability toward OER in alkaline media, with a low overpotential of 270 mV at 10 mA cm–2 and a small Tafel slope of 60 mV dec–1. Meanwhile, the obtained materials can deliver a large current density of 1000 mA cm–2 at an overpotential of only 410 mV for OER in 30 wt % KOH, an electrolyte widely used in commercial aqueous alkaline electrolyzers. The experimental results indicate that the vertical nanoarray structure offers a high specific surface area and exposes abundant active sites. In addition, the vanadium nitride and carbon nanotube hybrid can strongly decrease the charge transfer resistance, further facilitating the water-splitting reaction kinetics. [ABSTRACT FROM AUTHOR]

The effect of the concentration of vanadium nitride additive (in the range from 0 to 10 wt %) on the phase formation, hardness, and fracture toughness of composite diamond-containing materials based on the 51Fe–32Cu–9Ni–8Sn matrix molded by cold pressing and subsequent vacuum hot pressing is investigated. It is found that the addition of 10 wt % of vanadium nitride to the 51Fe–32Cu–9Ni–8Sn composite is accompanied by an increase in the hardness from 3.86 to 8.58 GPa with a slight decrease in the fracture toughness from 5.55 to 4.76 MPa m1/2. Moreover, the H(CVN) dependence has two characteristic segments that differ in the slope. The hardness increases insignificantly (from 3.86 to 5.26 GPa) in the range of 0 < CVN < 4 wt %, while the second region (CVN > 4 wt %) is characterized by a more substantial increase in the hardness and a more significant decrease in the grain size. It is shown that these parameters are achieved owing to the dispersion mechanism of strengthening and modification of the structure (a decrease in the mean particle size of the matrix phase, the formation of new (Fe3Ni)0.5 and Cu3Fe17 phases, and the precipitation of primary and secondary phases of vanadium nitride) and phase composition of the composites. [ABSTRACT FROM AUTHOR]

The energy storage devices for flexible/wearable and portable electronics are on immediate requirement demanding for high-performance flexible supercapacitors. Nevertheless, the real-time application of advanced electronics necessitates supercapacitors to own admirable mechanical properties to endure rigorous straining environments. Also, it is necessary to reduce the mass and volume of the whole device. Therefore, constructing a high-performance flexible supercapacitor based on better electrochemical and significant mechanical properties is still a formidable task. Herein, we have successfully fabricated a vanadium nitride thin film electrode onto the flexible, thin, and light-weight graphite paper substrate via reactive direct current (DC) magnetron sputtering method. The as-fabricated graphite sheets current collector is flexible, thin, light-weight, electrically conductiviting, cost-effective, and easy to fabricate. Furthermore, the as-prepared binder-free flexible negative electrode displayed better supercapacitor performance in terms of specific capacitance and cycle stability. The negative electrode exhibited an areal capacitance of 91 mF cm−2 and better cycling stability with > 64% capacitance retention after 2000 cycles. Moreover, the flexible hybrid supercapacitor is fabricated with NiCo hydroxide and VN films and showed a maximum energy density of 1.80 μWh cm−2 and power density of 387.5 μW cm−2 and good stability. These results propose that the fabricated electrode has great prospective as a power source for flexible, wearable, and portable electronic devices. [ABSTRACT FROM AUTHOR]

In this paper, vanadium nitride (VN) thin films have been deposited on Al substrates by reactive magnetron sputtering. Thermochromic VO2 films have been obtained by air oxidation of VN samples performed at three temperatures (450, 525 and 550 °C) at various durations (lower than 50 min). X-ray diffraction and Raman spectrometry of the VN oxidized films indicate that VO2 and V2O5 are the only phases produced during the oxidation process. Vanadium dioxide is the first oxide formed. It coexists with VN in a long period at 450 °C or suddenly disappears at 525 and 550 °C. Whatever the temperature, V2O5 is exclusively detected after the total oxidation of VN. This oxide is detrimental to the thermochromic performance of films. The emissivity-switching properties of the oxidized films were analyzed by infrared camera in the 7.5–13 μm range. The comparison among all the samples exhibiting a thermochromic behavior shows that the maximum emissivity switch is independent of the oxidation temperature and the surface morphology of the samples. These results could open a new strategy in the investigation of VN oxidation as a method to obtain VO2, along with an insight into the correlation between surface morphology and optical properties.

In this study, three dispersants of polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG) and citric acid (CA) are used to optimize the structure of the precursor in order to prepare high quality VN. Under optimum condition, the VN with nitrogen content of 17.94 % is prepared by adding 5 % PVP. The sequence of phase evolution from the precursor to VN is: APV → V 2 O 5 → V 6 O 13 → V 7 O 13 → VO 2 → V 3 O 5 → V 2 O 3 → (VC) → VN. The precursors of adding 5 % PVP have lower E a of 0.17 kJ mol−1, 20.51 kJ mol−1 and 62.70 kJ mol−1 during reduction and nitration process, which is easier to be reduced and nitridated. PVP not only promotes the uniform dispersion of the carbon powders in the vanadium rich solution but also enhance the hydrogen bonding of APV ions to promote their nucleation and growth. The precursor with uniform and concentrated particle size distribution, complete and stable encapsulation of shell of APV and core of carbon powder, and uniform and moderate thickness of APV shell is successfully prepared by adding PVP. The precursor has a larger phase reaction interface and more reactive sites during the nitriding reduction process, which results in a faster reduction and nitriding rate. In comparison with the current process, the nitriding reaction temperature has been reduced from 1400 ∼ 1500 °C to 1150 ∼ 1200 °C, the reaction time has been shortened by 75 %, and the N 2 consumption has been reduced by 40 %. [Display omitted] • The precursors of adding 5 % PVP are easier to convert to low-valent VO x after 297°C. • The precursors of adding 5% PVP have lower E a and faster reaction rate during nitride reduction. • The nitrogen content of VN prepared with PVP reaches 17.94 %, which improves by 1.5 %. [ABSTRACT FROM AUTHOR]

Cubic vanadium nitride (VN) holds substantial promise as an anode material for supercapacitors, owing to its high conductivity, theoretical capacity, and a wide negative voltage window. However, the tendency of VN to agglomerate, coupled with poor cycling stability from irreversible volume expansion during charge-discharge cycles, hinders its application in asymmetric supercapacitors. In this work, we reported a one-pot molten salt pyrolysis method to prepare VN/nitrogen doped porous carbon (VN/NPC) materials. The nitrogen-doped carbon material with 3D hierarchical porous structure not only facilitates ion diffusion and charge transport, but also serve as a matrix to in-situ synthesis VN nanoparticles to improve the cycling performance. The VN/NPC exhibits a specific capacitance of 272.3 F/g at 2 mV/s, and 268 F/g at 0.5 A/g. In addition, the VN/NPC demonstrates an excellent cycling stability with only 7 % capacity decay after 10,000 cycles. Furthermore, the all-solid-state asymmetric supercapacitors (ASCs) constructed using VN/NPC as anode and NiCo-layered double hydroxides (NiCo-LDH) as cathode deliver remarkable energy densities of 61.1 and 22.9 Wh/kg at power densities of 700.4 and 7496.6 W/kg, respectively. In addition, this ASCs exhibits excellent cycling stability with 83 % capacity retention after 10,000 cycles. This work provides a green and facile method to prepare anode materials with high capacitance and excellent cycle performance for high energy density ASCs devices. [Display omitted] • VN/NPC was prepared by a one-pot molten salt pyrolysis method. • The VN/NPC exhibited specific capacitance of 272.3 F/g at 2 mV/s. • The all-solid-state asymmetric supercapacitor devices were assembled. • The devices demonstrated high energy density of 61.09 Wh/kg at 700.4 W/kg. [ABSTRACT FROM AUTHOR]

Vanadium-based compounds are highly regarded as potential cathodes for aqueous zinc-ion batteries (AZIBs) owing to the high theoretical capacity, diverse structural frameworks and abundant oxidation states. Nevertheless, the challenges such as slow diffusion kinetics, low electrical conductivity and inadequate structural stability restrict their further development. Herein, yolk shell-like SiO 2 -coated V 2 O 3 /VN heterojunction microspheres (VON@SiO 2) are synthesized through a hydrothermal method followed by annealing and subsequent SiO 2 coating. As an advanced cathode for AZIBs, the construction of V 2 O 3 /VN heterojunction effectively exposes reactive sites, leads to the reduction in interfacial charge transfer resistance, and thus improves the ion diffusion kinetics, while the surface coating of SiO 2 is beneficial for enhancing the structural stability of the material and further reduces the capacity fading. Additionally, the micromorphology of porous yolk shell-like microspheres self-assembled by nanoparticles contributes to the complete penetration of electrolyte and greatly exposing reactive sites. Based on synergistic engineering of heterojunction, surface coating and porous shell-like micromorphology, the synthesized VON@SiO 2 delivers excellent specific capacities of 483.5 mAh g−1 at 0.5 A g−1 and 294 mAh g−1 at 10 A g−1, and exhibits impressive cycling performance with 94 % of capacity retention after 1000 cycles at 10 A g−1. Further, in-situ XRD and ex-situ XPS reveals the mechanism of zinc ion storage. This work offers a valuable reference into the development of high-performance cathode materials for AZIBs by co-engineering of heterojunction, surface coating and micromorphology optimization. • The construction of V 2 O 3 /VN heterojunction exposes more reactive sites and reduces interfacial charge transfer resistance. • The surface coating of SiO 2 greatly enhances the microstructural stability, efficiently reducing the capacity fading. • The yolk-shell microstructure is beneficial for full penetration of electrolyte, promoting the electrochemical reaction. [ABSTRACT FROM AUTHOR]

Vanadium Nitride (VN) is attractive for energy storage due to its high conductivity (1.6 × 106 S/m) and specific capacitance (1350 F/g) but limited to alkaline electrolytes for redox. In contrast, V 2 O 3 is redox active but not very conductive. In these hybrids a mixture of VN and vanadium oxide (V 2 O 3) were encapsulated in electrospun carbon-nanofibers. A combination of VN and V 2 O 3 takes advantage of the high conductivity from VN and the redox activity from V 2 O 3. Additionally, having the vanadium encapsulated within the carbon can help with the stability as the electrolyte will not have direct interaction with the surface. These hybrids were made by in-situ nitridation of the encapsulated V 2 O 5 followed by ex-situ activation with carbon dioxide. The hybrids were characterized by XPS and Raman spectroscopy. Hybrids of VN/V 2 O 3 -CNF showed increased capacitance of 245 Fg−1 with energy and power densities of 70.2 Wh kg−1 and 1751 W kg−1 in ionic liquid electrolyte. The devices showed good cycle stability with ∼90 % retention after 10,000 cycles at a current density of 1 Ag−1. These findings highlight the potential of VN/V 2 O 3 -CNF hybrids as high-performance supercapacitor electrodes. The combination of high conductivity and redox activity, along with encapsulation within CNFs, opens promising avenues for advanced energy storage. [ABSTRACT FROM AUTHOR]

As a promising anode material in supercapacitors, vanadium nitride has been widely concerned due to its ultra‐high theoretical specific capacitance. However, its routine test capacitance value is still far from the theoretical value and its energy storage mechanism is controversial. In order to solve these two key problems, here we prepare interplanar spacing expanded vanadium nitride materials with different impurity atoms intercalation from two anionic precursors of vanadium‐based metal organic frameworks with different functional groups. The obtained vanadium nitride reaches a higher specific capacitance; and further, through ex situ X‐Ray diffraction and in situ Raman, the charge storage of vanadium nitride is contributed by two processes: the first benefit is from the K+ de/intercalation in the interplanar spacing, and the other one is derived from the redox reaction with OH− by adsorption on surface. Furthermore, both of the first principle calculation and extended experiments support this idea. We believe that such detailed research on the energy storage mechanism can provide a clear idea for the application of metal nitrides in supercapacitors and other energy storage devices. [ABSTRACT FROM AUTHOR]

The effects of the concentration of the nano-VN additive (in the range from 0 to 10 wt %) on the structure, the retention of diamond grains by metal matrix, and the mechanical properties (nanohardness H, elastic modulus E, stability of the material to elastic deformation H/E, and resistance of the material to plastic deformation H3/E2) of samples of composite diamond-containing materials (CDMs) based on the 51Fe–32Cu–9Ni–8Sn matrix formed by cold pressing with subsequent vacuum hot pressing are studied. It is shown that the structure of the sintered CDM sample based on the 51Fe–32Cu–9Ni–8Sn matrix consists of diamond grains and fcc solid solutions that contain iron, copper, nickel, and tin in different ratios. Under this condition, elements Fe, Cu, Ni, and Sn are not detected on the surface of diamond grains, and gaps and discontinuity flaws are observed at the diamond–matrix contact. The additions of nano-VN added to the composition of the CDM in the amounts of 2, 4, 6, and 8 wt % allow one to obtain more finely grained structures composed of solid solutions containing iron, copper, nickel, vanadium, and tin, as well as diamond grains, on the surfaces of which small amounts of the same elements are present. At the same time, the diamond-containing matrix contact is tight without visible gaps, discontinuity flaws, and other defects. It is found that the variation of the concentration of vanadium nitride is accompanied by a nonmonotonic change in H for the entire studied interval of the depth of indenter immersion into the sintered sample surfaces. The addition of 2 wt % nano-VN to the DCM provides increases in the H value of the matrix from 5.2 to 5.6 GPa, in the E value from 197 to 202 GPa, in the H/E ratio from 0.0264 to 0.0277, and in the H3/E2 ratio from 3.62 to 4.30 MPa. The largest increases in H (7.8 GPa), E (213 GPa), H/E (0.036), and H3/E2 (10.46 MPa) are found for the CDM sample containing nano-VN additive in the amount of 8 wt %. These characteristics are achieved owing to the dispersion mechanism of strengthening and the modification of the structure (a decrease in the mean grain size, the creation of a tight diamond–matrix contact, the formation of V, Fe, Ni, and Cu inclusions on the surface of diamond grains, and the disappearance of pores in the metal matrix) and phase composition of the composites. [ABSTRACT FROM AUTHOR]

A Platinum free hybrid counter electrode (CE) Vanadium nitride/graphene (VNGp) for dye‐sensitized solar cell (DSSC) was synthesized by hydrothermal method. The surface morphology and chemical composition of the as‐prepared VNGp composite were analyzed by X‐ray diffraction (XRD) analysis, Raman spectroscopy, high‐resolution electron transmission microscopy (HR‐TEM), and cyclic voltammetry (CV). The VNGp hybrid counter electrode displayed an adsorption‐controlled process towards the (I−/I3−) redox couple at CE/electrolyte interface and the value was calculated to be 3.16×10−9 mol/s by varying the scan rate. The exchange current density (Jo) was calculated as 6.59 mA/cm2 from the Tafel slope. The VNGp hybrid counter shows a maximum fill factor (FF) of 66.28 with high efficacy of 8.15 % under the illumination of 100 mW/cm2 as compared to the Pt CE for DSSC. [ABSTRACT FROM AUTHOR]

The rational design of highly effective and low-cost catalysts for oxygen evolution reaction (OER) is of prime importance for the development of water splitting. However, the activity of electrocatalysts still needs enhancement to satisfy the practical application. Herein, we report Co nanoparticles grafted on vanadium nitride (VN) surface via in situ phase separation method by nitriding Co 2 V 2 O 7 precursor. Benefiting the advantages of abundant active sites of Co, high conductivity and corrosion resistance of VN, the Co/VN achieves incredibly high activity and durability for OER with a low overpotential of 320 mV at a current density of 10 mV cm−2 with a small Tafel slope of 50.4 mV dec−1 and long-term stability. In addition, the in situ Raman further reveals the synergistic effect of Co and VN. Significantly, this study may enrich our knowledge and it can be extended to prepare other interconnected framework structures for the development of OER catalysts. [Display omitted] • Co nanoparticles are anchored on VN (Co/VN) is successful synthesized. • The Co nanoparticles can provide more active sites and VN boasts superior conductivity. • Co/VN displays a remarkable OER activity, exhibiting a high O 2 generation rate. [ABSTRACT FROM AUTHOR]

Eliminating the usage of metal current collectors and binders in traditional battery electrode configuration is an effective strategy to significantly improve the capacities of lithium ion batteries (LIBs). Herein, we demonstrate the construction of porous vanadium nitride (VN) nanosheet network in situ grown on nitrogen-rich (N-rich) carbon textile (N-C@P-VN) as lightweight and binder-free anode for LIBs. The N-rich carbon textile is used both as the current collector and host to store Li+, thus improving the specific capacities of binder-free VN anode and meanwhile reducing the inert mass of the whole cell. Moreover, the open spaces in carbon textile and vertically aligned pores in VN nanosheet network can not only provide an expressway for Li+ and e− transport, but also afford more active sites. As a result, the binder-free N-C@P-VN anode maintains a specific capacity of 1,040 mAh·g−1 (or an areal capacity of 2.6 mAh·cm−2) after 100 cycles at 0.1 mA·cm−2 in half cell. Moreover, in an assembled N-C@P-VN//LiFePO4 full cell, it exhibits an areal capacity of 1.7 mAh·cm−2 after 300 cycles at 0.1 C. The synergistic strategy of N-C substrate and porous VN network could be applied to guide rational design of similar N-C@nitride or sulfide hybrid systems with corresponding sulfur-doped carbon textile as the substrate. [ABSTRACT FROM AUTHOR]

We prepared samples of composite diamond-containing materials 10 mm in diameter and 8 mm in thickness, based on the 51Fe–32Cu–9Ni–8Sn matrix (wt %) with different (0–10 wt %) concentrations of vanadium nitride (VN), the physical the mechanical characteristics of which depend on the composition of the iron matrix. The optimal (cVN = 4%) concentration of vanadium nitride in the matrix of composites sintered in the temperature range of 20–1000°C at a pressure of 30 MPa for 5 min ensures the highest indices of the physicomechanical properties of the composites (Rbm = 1110 MPa and Rcm = 1410 MPa) due to the dispersion mechanism of strengthening and modification of the structure, that is, a decrease in the average grain size, the disappearance of pores, the formation of clusters of the inhibitor phase at the interphase boundaries, and the phase composition of the composites. All sintered samples containing VN powder additives in the charge are characterized by a more uniform distribution of phases and a more dispersed structure compared to a sample without VN additives. The structure of composites containing a VN additive consists of a solid solution of nitrogen and vanadium in α-iron and a mixture of Fe, Cu, Ni, and Sn phases and primary and secondary dispersed phases of vanadium nitride. [ABSTRACT FROM AUTHOR]

Vanadium nitride (VN) is a promising electrode material for sodium-ion storage due to its multivalent states and high electrical conductivity. However, its electrochemical performance has not been fully explored and the storage mechanism remains to be clarified up to date. Here, the possibility of VN/carbon hybrid nanorods synthesized from a metal-organic framework for ultrafast and durable sodium-ion storage is demonstrated. The VN/carbon electrode delivers a high specific capacity (352 mA h g -1 ), fast-charging capability (within 47.5 s), and ultralong cycling stability (10 000 cycles) for sodium-ion storage. In situ XRD characterization and density functional theory (DFT) calculations reveal that surface-redox reactions at vanadium sites are the dominant sodium-ion storage mechanism. An energy-power balanced hybrid capacitor device is verified by assembling the VN/carbon anode and active carbon cathode, and it shows a maximum energy density of 103 Wh kg -1 at a power density of 113 W kg -1 ., (© 2024 Wiley‐VCH GmbH.)