Hydrogen In Vanadium Research Articles

A High Discharge Power Density Single Cell of Hydrogen–Vanadium Flow Battery

A High Discharge Power Density Single Cell of Hydrogen–Vanadium Flow Battery

Intercalated PtCo Electrocatalyst of Vanadium Metal Oxide Increases Charge Density to Facilitate Hydrogen Evolution.

Efforts to develop high-performance electrocatalysts for the hydrogen evolution reaction (HER) are of utmost importance in ensuring sustainable hydrogen production. The controllable fabrication of inexpensive, durable, and high-efficient HER catalysts still remains a great challenge. Herein, we introduce a universal strategy aiming to achieve rapid synthesis of highly active hydrogen evolution catalysts using a controllable hydrogen insertion method and solvothermal process. Hydrogen vanadium bronze HxV2O5 was obtained through controlling the ethanol reaction rate in the oxidization process of hydrogen peroxide. Subsequently, the intermetallic PtCoVO supported on two-dimensional graphitic carbon nitride (g-C3N4) nanosheets was prepared by a solvothermal method at the oil/water interface. In terms of HER performance, PtCoVO/g-C3N4 demonstrates superior characteristics compared to PtCo/g-C3N4 and PtCoV/g-C3N4. This superiority can be attributed to the notable influence of oxygen vacancies in HxV2O5 on the electrical properties of the catalyst. By adjusting the relative proportions of metal atoms in the PtCoVO/g-C3N4 nanomaterials, the PtCoVO/g-C3N4 nanocomposites show significant HER overpotential of η10 = 92 mV, a Tafel slope of 65.21 mV dec-1, and outstanding stability (a continuous test lasting 48 h). The nanoarchitecture of a g-C3N4-supported PtCoVO nanoalloy catalyst exhibits exceptional resistance to nanoparticle migration and corrosion, owing to the strong interaction between the metal nanoparticles and the g-C3N4 support. Pt, Co, and V simultaneous doping has been shown by Density Functional Theory (DFT) calculations to enhance the density of states (DOS) at the Fermi level. This augmentation leads to a higher charge density and a reduction in the adsorption energy of intermediates.

HXV2O5 Nanocatalysts Combined with Ultrasound for Triple Amplification of Oxidative Stress to Enhance Cancer Catalytic Therapy

AbstractMultiple amplification of tumor oxidative stress has been demonstrated as efficient strategy to enhance the reactive oxygen species (ROS)‐mediated cancer therapy. Herein, vanadium‐based nanocatalysts, hydrogen vanadium bronzes (HXV2O5, for short HVO), were constructed and employed as novel biocatalysts for amplifying tumor oxidative stress and enhancing cancer catalytic therapy. Such HVO nanocatalysts harboring multivalent V element possessed multi‐functional catalytic activity in decomposing H2O2 into ⋅OH and depleting endogenous glutathione (GSH) to dually amplify tumor oxidative stress. Meanwhile, HVO nanocatalysts could also be activated by ultrasound to further triply amplify oxidative stress. The massive intracellular ROS caused mitochondrial dysfunction, DNA damage, cell cycle arrest, and cell proliferation inhibition, further realizing cancer cell death and tumor growth inhibition. Collectively, HVO nanocatalysts highlight the remarkable value of ROS‐mediated cancer therapies.

HX V2 O5 Nanocatalysts Combined with Ultrasound for Triple Amplification of Oxidative Stress to Enhance Cancer Catalytic Therapy.

Multiple amplification of tumor oxidative stress has been demonstrated as efficient strategy to enhance the reactive oxygen species (ROS)-mediated cancer therapy. Herein, vanadium-based nanocatalysts, hydrogen vanadium bronzes (HX V2 O5 , for short HVO), were constructed and employed as novel biocatalysts for amplifying tumor oxidative stress and enhancing cancer catalytic therapy. Such HVO nanocatalysts harboring multivalent V element possessed multi-functional catalytic activity in decomposing H2 O2 into ⋅OH and depleting endogenous glutathione (GSH) to dually amplify tumor oxidative stress. Meanwhile, HVO nanocatalysts could also be activated by ultrasound to further triply amplify oxidative stress. The massive intracellular ROS caused mitochondrial dysfunction, DNA damage, cell cycle arrest, and cell proliferation inhibition, further realizing cancer cell death and tumor growth inhibition. Collectively, HVO nanocatalysts highlight the remarkable value of ROS-mediated cancer therapies.

First-principles calculations of transition elements interaction with hydrogen in vanadium

We performed systematic first-principles calculations to investigate the interactions of 26 transition elements (TEs) with hydrogen (H) and vacancy in vanadium (V). In the presence of 26 substitutional solute elements (Sc,Ti,Mn,Cr,Co,Fe,Cu,Ni,Y,Zr,Mo,Nb,Rh,Ru,Pd,Tc,Ag,La,Hf,W,Ta,Os,Re,Pt,Ir,Au), H still prefers to occupy the tetrahedral interstitial sites. H is unstable for solute elements at the nearest octahedral interstitial sites except for Ni and Cu. Then we calculated the binding energies of TEs and H with their distances. H atoms are attractive with early three 3d/4d/5d TEs (Sc/Ti/Y/Zr/La/Hf) and repulsive with other TEs. And we predicted the effect of solid solution elements on H diffusivity, Sc/Y/Zr/La/Hf can significantly reduce the effective diffusivity of H, while other elements have little effect on it. In addition, most of TEs can stabilize TE-vacancy-H clusters, the interactions of all TE-vacancy-H clusters are attractive and decrease with the increase of atomic number in the same period. In the case of pre-existing TE-vacancy complex defects, most of TEs can reduce the binding strength of vacancy to H. These results deepened the understanding of the TEs-H interactions and H retention in V alloys under irradiation.

Study on the effect of electrode configuration on the performance of a hydrogen/vanadium redox flow battery

All-vanadium redox flow batteries (VRFBs) are one of the potential energy storage systems for renewable energy storage. The high cost of vanadium electrolytes is one of the barriers to VRFB commercialization. To reduce the cost of the battery, the aqueous negative electrolyte is replaced with gaseous hydrogen, whereas the positive electrolyte retains vanadium ions as a hydrogen–vanadium redox flow battery (HVRFB). Hydrogen can be supplied using renewable energy sources, which enhances the kinetics of the reaction. The HVRFB is investigated in this study by examining the effects of negative electrode configuration, Pt loading, humidity conditions, and electrolyte flow rate. Pt loading and positive electrolyte flow rate are discovered to have a significant effect on electrolyte utilization. The highest battery performance is obtained when the catalyst loading is set at 0.3 mg Pt cm−2 and the positive electrolyte flow rate is around 2 L h−1. The HVRFB operates continuously for 200 cycles and demonstrates an energy efficiency of around 88% when operated at a current density of 80 mA cm−2.

Boosting Zn2+ Diffusion via Tunnel-Type Hydrogen Vanadium Bronze for High-Performance Zinc Ion Batteries.

Aqueous zinc ion batteries (ZIBs) are emerging as a promising candidate in the post-lithium ion battery era, while the limited choice of cathode materials plagues their further development, especially the tunnel-type cathode materials with high electrochemical performance. Here, a tunnel-type vanadium-based compound based on hydrogen vanadium bronze (HxV2O5) microspheres has been fabricated and employed as the cathode for fast Zn2+ ions' intercalation/deintercalation, which delivers an excellent capacity (425 mAh g-1 at 0.1 A g-1), a remarkable cyclability (91.3% after 5000 cycles at 20 A g-1), and a sufficient energy density (311.5 Wh kg-1). As revealed by the experimental and theoretical results, such excellent electrochemical performance is confirmed to result from the fast ions/electrons diffusion kinetics promoted by the unique tunnel structure (3.7 × 4.22 Å2, along the c direction), which accomplishes a low Zn2+ ion diffusion barrier and the superior electron-transfer capability of HxV2O5. These results shed light on designing tunnel-type vanadium-based compounds to boost the prosperous development of Zn2+ ion storage cathodes.

Synthesis of hydrocarbon-vanadium thin films by a low energy plasma focus device

Synthesis of hydrocarbon-vanadium thin films by a low energy plasma focus device is reported. The thin films have organometallic structure and organometallic trovacenyl carboxylic acid anhydride (C26H22O3V2) is formed. The vanadium deposition process was achieved in methane atmosphere using different number (10, 20, and 30) of focused shots. Prior to deposition process, surface of pure vanadium substrate and the anode tip were exposed to atmosphere to allow the formation of vanadium trioxide (V2O3) and hydrogen vanadium bronze (HxV2O5) structures. During deposition process, HxV2O5 reacts with methane molecules and C26H22O3V2 molecular structure in nano-grain scale is created. The findings of present study indicates that C26H22O3V2 can be categorized as a semiconductor with band gap energy in the range of 1.20–1.35 eV. Furthermore, it is demonstrated that C26H22O3V2 molecular structure is not Raman active. Characteristics of the V2O3, HxV2O5 and C26H22O3V2 structures are investigated by crystalline, spectroscopy and microscopy methods. The average crystallite size of C26H22O3V2 was roughly 6 nm with almost 16% carbon deposited in the thin films. The Raman results are independent of the number of focused shots.

Permeation and diffusion of hydrogen in vanadium using deoxidation and glow-discharge surface cleaning techniques

Vanadium (V) is an attractive hydrogen separation membrane material. However, its diffusion behavior under hydrogen permeation is not well understood mainly because of surface oxidation. Here, we have attempted to observe the permeation of hydrogen through V by subjecting V samples to different surface treatments e.g., electropolishing and plasma-induced cleaning using a glow-discharge technique. We have achieved a high flux of hydrogen controlled by long-range diffusion under a low hydrogen potential at 723–973 K. The diffusion coefficients of hydrogen in defect-free and high-purity samples analyzed from the permeation curves at 823–973 K are almost consistent with the literature data obtained by Gorsky effect and absorption measurements. However, the activation energy of diffusion (19 kJ mol−1) is 8–14 kJ mol−1 higher than the literature values. This difference in activation energy suggests that permeation through the active surface of V is highly sensitive to trapping by oxygen—a slight amount of oxygen dissolved from a very thin native oxide layer would segregate near the surface to trap hydrogen. Furthermore, we have found that residual strain, grain boundaries, and lattice defects, induced by mechanical deformation, reduce the flux and retard the diffusion considerably.

Effect of Different Acid-Modified Coking Coals on Quinoline Adsorption.

The adsorption of quinoline from wastewater by coking coal (AC-1), HCl-modified coking coal (AC-2), HNO3-modified coking coal (AC-3), HF-modified coking coal (AC-4), and H2SO4-modified coking coals (AC-5) was investigated in this paper. The effects of acid-modified concentration, modification time, and adsorption time versus quinoline removal rate were studied by batch experiments. The quinoline concentration was measured by UV spectrophotometry, the average pore size and specific surface area of coking coal before and after modification were characterized through static nitrogen adsorption, the mineral composition of coking coal was tested by X-ray diffraction, the surface functional groups were tested by Fourier transform infrared spectroscopy, and the surface topography was tested using a scanning electron microscope. The experimental results showed that the adsorption capacity of coking coals was the best when both the modification time was 120 min and the acid-modified concentration was 0.1 mol·L–1 and the quinoline removal rate reaches the highest when the adsorption time was 120 min. The specific surface area of AC-2 increased from 2.898 to 3.637 m2·g–1, and the removal rate of quinoline increased from 77.64 to 90.61%. Acids reacted with inorganic mineral impurities within coking coal such as hydrogen vanadium phosphate hydrate, which caused an increase in the specific surface area. A new peak appeared in the Fourier transform infrared spectroscopy pattern at the wavenumber 2300 cm–1. The surface of coking coal modified by acids was rougher than that of AC-1. The adsorption capacity of coking coal was improved after modification, and modified coking coals have the highest potential as low-cost adsorbents for quinoline removal.

Effect of impurity carbon and oxygen atoms on the behavior of hydrogen in vanadium in a fusion environment: A first-principles study

We have investigated the effect of impurity X (X = C and O) atoms on the behavior of hydrogen in vanadium, which is an ideal structural material for nuclear fusion reactors, by first-principles calculations. We found that (1) in bulk V, the interaction between an interstitial H atom and an X atom is repulsive, and the interaction with O is much stronger than that with C. (2) The X–vacancy (vac) cluster can act as a center for capturing H in V. The C-vac cluster can trap as many as two H atoms, while the O–vac cluster can capture up to four H atoms. (3) C and O impurities can effectively decrease the trapping energy of a single H atom in a vacancy. The H-trapping energies in the C–vac and O–vac complexes are 0.88 eV and 0.46 eV, respectively, both of which are lower than those in the X-free vacancy. (4) Both H–X and X-metal interactions affect the H solubility in V. The above results provide important information for application of vanadium as a structural material for nuclear fusion tokamaks.

First-principles study of hydrogen behavior in vanadium-based binary alloy membranes for hydrogen separation

Vanadium-based alloys are considered to be one of the most promising hydrogen separation membranes due to their high hydrogen permeability. In this study, we investigate the dissolution and diffusion behaviors of hydrogen in vanadium-based binary alloys, V15M (where M = Al, Ti, Cr, Fe, Ni and Nb) alloys, using first-principles method based on density functional theory. The dissolution of hydrogen in V15M alloys is affected by both the elastic and electronic properties, but the elastic effect is the main factor. The H solution energies in the alloys follow the sequence: VTi < VNb < VAl < VCr < VNi < VFe, and a smaller atom size increase the H solution energy. Therefore, the addition of alloying elements with smaller atomic sizes can reduce the solubility of hydrogen in vanadium and inhibit hydrogen embrittlement. For hydrogen diffusion, alloying elements Al, Ti and Nb can be good candidates because they have a higher diffusion coefficient. The VTi alloy has the highest hydrogen permeability, but will have serious hydrogen embrittlement due to the increased H solubility.

Influence of site occupancy on diffusion of hydrogen in vanadium

We investigate the effect of site occupancy on the chemical diffusion of hydrogen in strained vanadium. The diffusion rate is found to decrease substantially, when hydrogen is occupying octahedral ...

Diffusion and retention of hydrogen in vanadium in presence of Ti and Cr: First-principles investigations

We systemically investigated diffusion and retention of hydrogen (H) in vanadium (V) in presence of Ti/Cr and determined the stability of Hn clusters and Hn-vacancy clusters (n = 1–6) near Cr/Ti using first-principles calculations. H prefers a tetrahedral site near Ti than other interstitial sites. H-Cr interactions have a weak repulsion contrarily H-Ti interactions have a weak attraction. Kinetically, H diffusion barrier decreases towards Ti, while it increases towards Cr. Ti and Cr block H mobility in V alloys. Moreover, Hn Ti clusters are quite stable while HnCr clusters are less stable. Ti enhances H retention by acting as a trapping site for multiple H atoms in similar with vacancy, and a Ti atom can trap at least six H atoms. The stability of H-vacancy-Cr/Ti complexes and vacancy-Cr/Ti trapping for multiple H atoms are discussed. The findings are valuable for understanding the mechanism of H bubble nucleation and H embrittlement under irradiation.

Interactions of hydrogen with vanadium in crystalline silicon

In this work, we have investigated interactions of vanadium with hydrogen in n‐ and p‐type float zone grown silicon using deep level transient spectroscopy (DLTS), Laplace DLTS, capacitance‐voltage and secondary ion mass spectroscopy measurements (SIMS). Vanadium was introduced into Si wafers by ion implantation with subsequent heat treatments at 800 °C for removing the implantation induced lattice damage. In the DLTS spectra of the annealed samples, we have observed two deep level states due to interstitial vanadium (Vi) atoms in n‐type Si and one in p‐type Si. A comparison of concentration profiles of the Vi atoms with those for the total concentration of V measured by SIMS has shown that at the projected implantation depth the [Vi]/[Vtotal] ratio is less than 0.05 at chemical concentration of vanadium of 1 × 1015 cm−3, so the majority of V atoms are in electrically inactive states in this region. At lower chemical concentrations of vanadium, similar values of [Vi] and [Vtotal] are observed. After the treatment of the n‐type V‐doped samples in a remote hydrogen plasma at room temperature, we have found that the concentration of the Vi atoms decreases while additional electron traps emerge in the DLTS spectra. A trap with the highest concentration has been attributed to a vanadium–hydrogen complex. In the p‐type Si:V samples, no new levels have emerged in the DLTS spectra after the H‐plasma treatments. It is suggested that in p‐type Si:V an interaction of H atoms with the Vi atoms is suppressed because of the Coulombic repulsion of positively charged Vi and hydrogen defects. It is argued that no electrically active defects are formed in either the n‐ or p‐type Si:V samples due to possible interactions of hydrogen with electrically inactive V‐related defects. We present evidence that annealing of the n‐type Si:V samples in the temperature range 75–125 °C following the application of hydrogen plasma results in up to 20% decrease in the total concentration of electrically active V‐related defects, indicating the formation of some electrically inactive V–H complexes. Heat treatments at temperatures above 175 °C have resulted in the disappearance of all the V–H complexes and recovery of electrical activity of the Vi atoms.

Hydrogen in vanadium: Site occupancy and isotope effects

We discuss the influence of site occupancy on the absorption of the hydrogen isotopes H and D in thin V(001) layers. By growing V(001) under biaxial compressive strain in Fe/V(001) superlattices, the hydrogen (H as well as D) is forced to reside exclusively in octahedral (${\mathrm{O}}_{z}$) sites, even at the lowest concentrations. A weakening of the isotope effects is observed when hydrogen resides in octahedral as compared to tetrahedral sites.

Study of Loss Mechanisms Using Half-Cell Measurements in a Regenerative Hydrogen Vanadium Fuel Cell

The positioning of reference electrodes in redox flow batteries without disturbing the cell operation represents a great challenge. However decoupling anode and cathode processes is crucial in order to fully understand the losses in the system so it can be further optimized. The feasibility of a regenerative fuel cell based on an V(IV)/V(V) electrolyte and hydrogen gas has previously been demonstrated. In this investigation, using electrochemical impedance spectroscopy, the various losses of the cathode, anode and whole cell were established using an alternative reference electrode set-up. The findings showed that the largest irreversible losses under the conditions tested arose from diffusion limitations in the cathode and the effect of vanadium crossover and therefore adsorption onto the platinum layer of the hydrogen electrode leading to higher losses on the anode. These results highlight the potential for further improvement and optimization of cell design and materials for both electrodes in the Regenerative Hydrogen Vanadium Fuel Cell.

In-Situ Deuterium Charging for Direct Detection of Hydrogen in Vanadium by Atom Probe Tomography

Journal Article In-Situ Deuterium Charging for Direct Detection of Hydrogen in Vanadium by Atom Probe Tomography Get access S Dumpala, S Dumpala Department of Materials Science and Engineering and Institute for Combinatorial Discovery, IowaState University, 2220 Hoover Hall, Iowa State University, Ames, USA Search for other works by this author on: Oxford Academic Google Scholar D Haley, D Haley Department of Materials, University of Oxford, Parks Road, Oxford OX13PH, UK Search for other works by this author on: Oxford Academic Google Scholar SR Broderick, SR Broderick Department of Materials Science and Engineering and Institute for Combinatorial Discovery, IowaState University, 2220 Hoover Hall, Iowa State University, Ames, USA Search for other works by this author on: Oxford Academic Google Scholar PAJ Bagot, PAJ Bagot Department of Materials, University of Oxford, Parks Road, Oxford OX13PH, UK Search for other works by this author on: Oxford Academic Google Scholar M P Moody, M P Moody Department of Materials, University of Oxford, Parks Road, Oxford OX13PH, UK Search for other works by this author on: Oxford Academic Google Scholar K Rajan K Rajan Department of Materials Science and Engineering and Institute for Combinatorial Discovery, IowaState University, 2220 Hoover Hall, Iowa State University, Ames, USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 21, Issue S3, 1 August 2015, Pages 695–696, https://doi.org/10.1017/S1431927615004274 Published: 23 September 2015

Regenerative Fuel Cells for Energy Storage Application: Performance Limitation Studies

Redox flow batteries are a potentially versatile and attractive solution to store and deliver energy over the kW/kWh to MW/MWh range. A variety of redox flow chemistries exist, with all-vanadium battery being the most mature and developed. Nonetheless, all-vanadium systems suffer from a relatively low power density, specific energy and high cost, associated with the use of vanadium based electrolytes. These issues can be circumvented by replacing the vanadium anolyte or catholyte with a cheaper alternative. Particularly, novel regenerative fuel cells have been developed that utilise a combination of a liquid and a gaseous redox reactions; either hydrogen oxidation reaction on the anode side or oxygen reduction reaction on the cathode side. Previous work by the authors has demonstrated a regenerative fuel cell based on hydrogen/vanadium redox reactions whichachieved a specific power of 200 mW/cm2. Further optimisation of this system has increased the power density to more than 400 mW/cm2. This paper will present a study of the performance limiting factors in the Regenerative Hydrogen Vanadium Fuel Cell, showing how this information can be generally implemented in other energy storage systems utilising hydrogen and metal redox couples.

Effect of uniaxial strain on the site occupancy of hydrogen in vanadium from density-functional calculations.

We investigate the influence of uniaxial strain on the site occupancy of hydrogen in vanadium, using density functional theory. The site occupancy is found to be strongly influenced by the strain state of the lattice. The results provide the conceptual framework for the atomistic description of the observed hysteresis in the to phase transition in bulk, as well as the preferred octahedral occupancy of hydrogen in strained V layers.