Porous Vanadium Nitride Research Articles

Vanadium nitride/reduced graphene oxide composite interlayer with dual lithium-polysulfide adsorption effect for lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) have been developed as next-generation power sources owing to their high theoretical capacities and energy densities, cost effectiveness, and abundance. However, the low electrical conductivity of sulfur in the cathode and the dissolution of lithium polysulfides (LiPS) into the liquid electrolyte are challenging issues that deteriorate both capacity and energy density. Herein, a porous vanadium nitride and reduced graphene oxide (VN/rGO) composite is prepared as an LSB interlayer that enhances conversion and redox reactions and increases sulfur utilization. Polar VN in the VN/rGO interlayer chemically adsorbs LiPS while rGO provides excellent electrical conduction and a high specific surface area for the physical adsorption of LiPS. The dual LiPS adsorption effect of VN/rGO suppresses shuttle effect and enhances electrochemical performance, leading to specific capacities of 1025 and 693 mA h g−1 at 0.5 and 2 C, respectively, and a retention of 81 % at 0.5 C after 200 cycles.

Progressive activation of porous vanadium nitride microspheres with intercalation-conversion reactions toward high performance over a wide temperature range for zinc-ion batteries

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 (VOx). With the same mass of VN and VOx, 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.

Polyaniline-Coated Porous Vanadium Nitride Microrods for Enhanced Performance of a Lithium–Sulfur Battery

To solve the slow kinetics of polysulfide conversion reaction in Li-S battery, many transition metal nitrides were developed for sulfur hosts. Herein, novel polyaniline-coated porous vanadium nitride (VN) microrods were synthesized via a calcination, washing and polyaniline-coating process, which served as sulfur host for Li-S battery exhibited high electrochemical performance. The porous VN microrods with high specific surface area provided enough interspace to overcome the volume change of the cathode. The outer layer of polyaniline as a conductive shell enhanced the cathode conductivity, effectively blocked the shuttle effect of polysulfides, thus improving the cycling capacity of Li-S battery. The cathode exhibited an initial capacity of 1007 mAh g-1 at 0.5 A g-1, and the reversible capacity remained at 735 mAh g-1 over 150 cycles.

Hybridization of porous vanadium nitride nanosheets with cobalt-encapsulated nitrogen-doped carbon nanotubes on carbon cloth as an advanced monolithic negative electrode for boosting asymmetric supercapacitors

The low energy density of asymmetric supercapacitors (ASCs) is mainly attributable to the low capacitance of the negative electrode; consequently, developing negative electrodes with high capacitance is crucial to boosting the energy density of ASCs. Vanadium nitride (VN), with excellent theoretical capacitance, is an ideal negative electrode material, but its low conductivity and poor electrochemical stability limit its application in energy storage. Herein, we design a high-performance monolithic negative electrode of ASCs that consists of well-defined porous VN nanosheets stacked with small nanoparticles decorated on a conductive substrate of ultrafine cobalt-encapsulated nitrogen-doped carbon nanotubes on carbon cloth (VN NS/Co@NCNTs/CC). Because the Co@NCNTs/CC substrate can enhance conductivity and facilitate the dispersion of active species and the exposure of more reaction sites, the newly developed porous VN NS/Co@NCNTs/CC negative electrode exhibits a high capacitance of 1016 mF cm−2 (782.3 F g−1) at 2 mA cm−2 and a superior cycle stability (110% capacitance retention after 11,000 cycles). To construct the ASC, a positive electrode of manganese dioxide (MnO2) nanoneedles grown on Co@NCNTs/CC (MnO2 NN/Co@NCNTs/CC) was also built using a similar preparation method. Benefiting from the wide operating voltage and high capacitance of the negative and positive electrodes, the assembled ASC can operate stably at a high voltage of 2 V. More importantly, the ASC can reach an energy density of 29.9 μWh cm−2 (23.9 Wh kg−1) and a capacitance retention of 94.3 % after 20,000 cycles, outperforming most of the reported aqueous ASC devices. This study provides a feasible way to reasonably design ASC electrodes with superior electrochemical performance.

Synthesis and microwave absorption properties of porous vanadium nitride microspheres

Synthesis and microwave absorption properties of porous vanadium nitride microspheres

Direct growth of porous vanadium nitride on carbon cloth with commercial-level mass loading for solid-state supercapacitors

Mass production of wearable devices with effective three-dimensional (3D) structure is a vital prerequisite for practical energy storage. Vanadium nitride (VN) has been identified as a promising supercapacitor electrode due to its wide negative potential working window, high specific capacitance and outstanding electrical conductivity, Herein, porous VN is grown on carbon cloth (CC) by a dip-coating and nitridation method. Such a VN/CC electrode provides effective 3D structure is beneficial for high mass loading (up to 28.3 mg cm−2) with high specific capacitance. Consequently, the as-prepared VN/CC electrode can achieve high areal capacitance of 3.34 F cm−2 at 5 mA cm−2. As a result, the flexible symmetric supercapacitor shows robust cycling stability (96% retention over 10,000 cycles) with PVA/KOH gel electrolyte. In addition, high energy/power density (0.341 mWh cm−2 at 1.92 mW cm−2) and excellent cycling performance (87% retention over 8000 cycles) are achieved in the assembled solid-state asymmetric supercapacitor cell with Zn−Ni−Co ternary oxides (ZNCO)/NF cathode and VN/CC anode. The results provide a simple route to prepare high mass loading porous VN-based electrodes with outstanding areal capacitance. It is believed that this strategy will favor the development of other transition metal nitride electrodes for commercial use in the future.

Porous single-crystalline vanadium nitride octahedra with a unique electrocatalytic performance

Here we grow porous single-crystalline vanadium nitride that has a good performance in the HER, showing high activity and stability.

Hybridization of Porous Vanadium Nitride Nanosheets with Cobalt-Encapsulated Nitrogen-Doped Carbon Nanotubes on Carbon Cloth as an Advanced Monolithic Negative Electrode for Boosting Asymmetric Supercapacitors

Hybridization of Porous Vanadium Nitride Nanosheets with Cobalt-Encapsulated Nitrogen-Doped Carbon Nanotubes on Carbon Cloth as an Advanced Monolithic Negative Electrode for Boosting Asymmetric Supercapacitors

Direct Growth of Porous Vanadium Nitride on Carbon Cloth with Commercial-Level Mass Loading for High-Performance Solid-State Supercapacitors

Direct Growth of Porous Vanadium Nitride on Carbon Cloth with Commercial-Level Mass Loading for High-Performance Solid-State Supercapacitors

Multilayer Porous Vanadium Nitride Microsheets Anodes for Highly Stable Na-ion Batteries

Sodiumion batteries(SIBs) have attracted intensive attention as promising alternative to lithium-ionbatteries(LIBs) for large scale energy storage systems because of low cost of sodium, similar energy storage mechanism and the reasonable performance. However, it is still a great challenge to search and design a robust structure of anode materials with excellent cycling stability and high rate capability for SIBs. Herein, multilayer porous vanadium nitride (VN) microsheets are synthesized through a facile and scalable hydrothermal synthesis-nitrogenization strategy as an effective anode material for SIBs. The multilayer porous VN microsheets not only offer more active sites for fast Na+ insertion/extraction process and short diffusion pathway, but also effectively buffer the volume change of anode due to more space in the multilayer porous structure. The large proportions of capacitive behavior imply that the Na+ charge storage depends on the intercalation pseudocapacitive mechanism. The multilayer porous VN microsheets electrodes manifest excellent cycling stability and rate capability, delivering a discharge capacity of 156.1 mA·h/g at 200 mA/g after 100 cycles, and a discharge capacity of 111.9 mA·h/g at 1.0 A/g even after 2300 cycles with the Coulombic efficiency of nearly 100%.

Probing the interaction mechanism of heterostructured VOxNy nanoparticles supported in nitrogen-doped reduced graphene oxide aerogel as an efficient polysulfide electrocatalyst for stable sulfur cathodes

Reversible redox of sulfur to lithium sulfide through a series of lithium polysulfides (LiPS) still pose a key challenge to appreciate high-performance sulfur cathodes mainly because of shuttling phenomenon and sluggish kinetics. Herein, a simple novel synthetic approach has been presented to realize porous vanadium nitride oxide (VOxNy) nanoparticles spatially decorated within nitrogen doped reduced graphene aerogel (VONNG) via concurrent in-situ nitridation and carbonization processes. Nitrogen-doped reduced graphene aerogel enhances the physical retention and polar interaction of LiPS and contributes toward the overall conductivity of the matrix. Whereas, vanadium nitride oxide has exhibited a redox potential window intermediate to its oxides’ counterparts around which LiPS can form polythionate complexes to enhance the kinetics and LiPS retention by exploiting the V–N and V–O interfaces at cathode. The interaction mechanism has been probed through in-operando Raman spectroscopy, XPS and electroanalytical methods. The assembled cells from VONNG/S cathodes exhibit the initial discharge capacity of 1400 mAh g−1 at 0.05 C, 1250 mAh g−1 at 0.1 C and maintained reversible capacity about 700 mA h g−1 at 0.2 C after 200 cycles. The loss in capacity is less than 0.05% per cycle for 850 cycles with Coulombic efficiency close to 99% even at 5C.

Preparation of high purity vanadium nitride by magnesiothermic reduction of V2O3 followed by nitriding in N2 atmosphere

Abstract High purity vanadium nitride (VN) powders were prepared via a two-step process using vanadium trioxide (V2O3) as the raw material. The V2O3 was firstly reduced at 873 K in Ar atmosphere via magnesiothermic reduction reaction to get the mixture of V and MgO, and then the products were further nitrided at 1473 K in N2 atmosphere. Finally, the as-prepared samples were acid-leached to obtain pure VN powders. X-ray diffractometry and field-emission scanning electron microscopy were used to analyze the phase transition and morphological evolution of the samples. The results reveal that the overall morphology of the obtained VN powder retains the morphology of the initial V2O3 powders. After removing MgO by acidic leaching, the porous VN particles can be obtained, with the oxygen content of 0.178 wt.%. Compared with the traditional methods, high purity VN powders with a small amount of oxygen and no carbon can be obtained.

Hierarchical Nanosheets/Walls Structured Carbon-Coated Porous Vanadium Nitride Anodes Enable Wide-Voltage-Window Aqueous Asymmetric Supercapacitors with High Energy Density.

The energy density of aqueous asymmetric supercapacitors (ASCs) is usually limited by low potential windows and capacitances of both anode and cathode. Herein, a facile strategy to fabricate hierarchical carbon‐coated porous vanadium nitride nanosheet arrays on vertically aligned carbon walls (CC/CW/p‐VN@C) as anode for aqueous ASCs is reported. The potential window of CC/CW/p‐VN@C electrode can be stably extended to –1.3 to 0 V (vs Ag/AgCl) with greatly improved specific capacitance (604.8 F g−1 at 1 A g−1), excellent rate capability (368 F g−1 at 60 A g−1), and remarkable electrochemical stability. To construct ASCs, a Birnessite Na0.5MnO2 nanosheet arrays (CC/CW/Na0.5MnO2) cathode is similarly built. Benefiting from the matchable potential windows and high specific capacitances of the rationally designed anode and cathode, aqueous CC/CW/p‐VN@C||CC/CW/Na0.5MnO2 ASCs with a wide voltage window of 2.6 V are fabricated. Moreover, the ASCs showcase an ultrahigh energy density up to 96.7 W h kg−1 at a high power density of 1294 W kg−1, and excellent cycling stability (92.5% retention after 10 000 cycles), outperforming most of previously reported ASCs and even comparable to that of organic electrolyte supercapacitors (SCs). This efficient strategy for fabricating 2.6 V aqueous ASCs suggests a promising research system for high energy density SCs.

Co,N-Codoped porous vanadium nitride nanoplates as superior bifunctional electrocatalysts for hydrogen evolution and oxygen reduction reactions.

Developing efficient and low-cost bifunctional electrocatalysts as candidates for Pt-based materials to satisfy commercial applications in the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) is still very challenging. Herein, we show that Co,N-codoped porous vanadium nitride (VCoN) nanoplates are successfully synthesized via a simple one-step pyrolysis protocol without the use of NH3 gas. We also demonstrate that the crystallization, surface chemical state and porosity of vanadium nitride are well modulated by inventively using Co dopants as structural inducers. The resulting VCoN material exhibits an excellent catalytic activity towards the HER in alkaline media, with an extremely low onset potential of -0.03 V, an overpotential of 179 mV at 10 mA cm-2, and a remarkable durability for over 100 h. Moreover, it shows a superior ORR performance, which compares favorably with commercial 20% Pt/C, exhibiting an onset potential of ∼1.02 V, a half-wave potential of ∼0.91 V and a weak potential shift (-5 mV) after 2000 cycles at 1600 rpm in 0.1 M KOH. Such excellent electrocatalytic performance primarily contributes to the unique structural features of the heteroatom N (pyrrolic and graphitic N) and Co codoping in favor of improving the electrical conductivity and the high porosity contributing to exposing numerous catalytic active sites.

Synthesis and Electrochemical Performance of Spherical Porous Vanadium Nitride

Synthesis and Electrochemical Performance of Spherical Porous Vanadium Nitride

On Chip Interdigitated Micro‐Supercapacitors Based on Sputtered Bifunctional Vanadium Nitride Thin Films with Finely Tuned Inter‐ and Intracolumnar Porosities

AbstractMicro‐supercapacitors (MSC) are considered as promising miniaturized electrochemical energy storage devices for Internet of Things applications. Unfortunately, the technological readiness level of these devices is still at the lab scale with the development of individual prototypes due to the difficulty to produce high performance porous electrode material with microelectronic equipment available in pilot production lines. Here, the collective fabrication of on chip MSC based on sputtered porous vanadium nitride (VN) bifunctional material is reported. For the first time in the field of MSC, the porosity of the sputtered VN thin films is fine‐tuned at the nanoscale level in order to produce high capacitance and high conductive electrodes. Interdigitated MSC based on optimized VN thin films are fabricated on silicon wafers using microelectronic facilities. 2 μWh cm−2/10 mWh cm−3 energy densities are reached while keeping a high power density (10 mW cm−2/>50 W cm−3) owing to high electrical conductivity of VN layers. Sputtered vanadium nitride thin films are demonstrated to be suitable pseudocapacitive electrodes and highly conductive current collectors for MSC applications. These findings represent a major advance in order to go toward the large‐scale deployment of such miniaturized power sources.

All-solid-state high-energy planar hybrid micro-supercapacitors based on 2D VN nanosheets and Co(OH)2 nanoflowers

Planar micro-supercapacitors are recognized as one of the most competitive on-chip power sources for integrated electronics. However, most reported symmetric micro-supercapacitors suffer from low energy density. Herein, we demonstrate the facile mask-assisted fabrication of new-type all-solid-state planar hybrid micro-supercapacitors with high energy density, based on interdigital patterned films of porous vanadium nitride nanosheets as negative electrode and Co(OH)2 nanoflowers as positive electrode. The resultant planar hybrid micro-supercapacitors display high areal capacitance of 21 mF cm−2 and volumetric capacitance of 39.7 F cm−3 at 0.2 mA cm−2, and exhibit remarkable energy density of 12.4 mWh cm−3 and power density of 1750 mW cm−3, based on the whole device, outperforming most reported planar hybrid micro-supercapacitors and planar asymmetric micro-supercapacitors. Moreover, all-solid-state planar hybrid micro-supercapacitors show excellent cyclability with 84% capacitance retention after 10000 cycles, and exceptionally mechanical flexibility. Therefore, our proposed strategy for the simplified construction of planar hybrid micro-supercapacitors will offer numerous opportunities of utilizing graphene and other 2D nanosheets for high-energy microscale supercapacitors for electronics.

A 3D architecture composite of porous vanadium nitride nanoribbons and reduced graphene oxide as a high-efficiency counter electrode for dye-sensitized solar cells.

A three-dimensional (3D) porous architecture combining porous vanadium nitride nanoribbons with reduced graphene oxide was prepared through a hydrothermal process and subsequent thermal annealing in an ammonia/argon mixed atmosphere. Then, the obtained 3D porous vanadium nitride nanoribbon/reduced graphene oxide (PVNN/RGO) composite was explored as the counter electrode of dye-sensitized solar cells (DSCs). As evidenced by the electrochemical measurements, the 3D PVNN/RGO composite demonstrates excellent electrocatalytic performance, which is comparable to that of Pt. This can be attributed to the fact that the 3D architecture composite of porous vanadium nitride and reduced graphene oxide can simultaneously provide a favorable electrolyte diffusion channel, a fast electron-transport network, and an abundance of efficient electrocatalytic active sites. By employing such PVNN/RGO composite as the counter electrode, the fabricated DSC can achieve a conversion efficiency of 7.43%, which is comparable to that of the conventional Pt counter electrode (7.74%). Therefore, the 3D PVNN/RGO composite is a promising low-cost alternative to the expensive Pt as a counter electrode in DSCs.

Three-dimensional porous vanadium nitride nanoribbon aerogels as Pt-free counter electrode for high-performance dye-sensitized solar cells

Three-dimensional (3D) porous vanadium nitride nanoribbon aerogels (PVNNRAs) are prepared by hydrothermal synthesis and subsequent nitridation in ammonia/argon atmosphere and investigated as Pt-free counter electrode in dye-sensitized solar cells (DSCs). 3D porous nanoribbon aerogel can simultaneously offer more electrocatalytic active sites, a fast electron-transport pathway, and a favorable electrolyte diffusion channel, which endows the PVNNRA electrode with high electrocatalytic activity for the reduction of I3−. Under full-sun illumination (AM 1.5, 100mWcm−2), the DSC fabricated with PVNNRA counter electrode achieves a conversion efficiency of 7.05%, which is comparable to that of DSCs fabricated with Pt counter electrode. In addition, the PVNNRA electrode exhibits good stability in I−/I3− redox electrolyte. Thus, 3D PVNNRAs can be considered as a cost-effective alternative to Pt as the counter electrode of DSCs.

Porous vanadium nitride nanoribbon aerogel and its electrochemical properties

Porous vanadium nitride nanoribbon aerogel (PVNNRA) was prepared by hydrothermal reaction at 180°C and subsequent ammonia treatment at 550°C using NH4VO3 as the precursor. The electrochemical properties of PVNNRA were discussed. SEM and TEM images demonstrated that as-prepared vanadium nitride showed a porous nanoribbon morphology with the width of 100–400 nm and the pore size of 10–20 nm. The analysis of electrochemical impedance spectroscopy indicated that the charge-transfer resistance of PVNNRA electrode was 1.36 Ω cm2, indicating a high electrocatalytic activity for I3− reduction. The dye-sensitized solar cell fabricated with PVNNRA counter electrode achieved a conversion efficiency of 7.05%, which is closed to that of the cell fabricated with Pt counter electrode. The results of cyclic voltammetry and galvanostatic charge/discharge tests demonstrated that PVNNRA has a good capacitive performance. At the current density of 0.5 A/g, PVNNRA exhibited a specific capacitance of 292.2 F/g in 2 mol/L KOH aqueous solution. Therefore, as-prepared PVNNRA can be considered as an effective electrode material for application in dye-sensitized solar cells and supercapacitors