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NO x abatement has been an indispensable part of environmental catalysis for decades. Selective catalytic reduction with ammonia using V 2 O 5 /TiO 2 is an important technology for removing NO x emitted from industrial facilities. However, it has been a huge challenge for the catalyst to operate at low temperatures, because ammonium bisulfate (ABS) forms and causes deactivation by blocking the pores of the catalyst. Here, we report that physically mixed H-Y zeolite effectively protects vanadium active sites by trapping ABS in micropores. The mixed catalysts operate stably at a low temperature of 220 °C, which is below the dew point of ABS. The sulfur resistance of this system is fully maintained during repeated aging/regeneration cycles because the trapped ABS easily decomposes at 350 °C. Further investigations reveal that the pore structure and the amount of framework Al determined the trapping ability of various zeolites. V-based NO x abatement systems are limited in operating at low-temperatures due to the formation of ammonium bisulfate that blocks active sites of catalysts. Here, the authors report that physically mixed zeolites trap ammonium bisulfate in their micropores, thereby protecting the catalysts.

Vanadium has various oxidation states and multiple crystalline phases that make it interesting for various applications. The oxidation state transition and crystal formation of vanadium oxide (VOx) were affected by growth conditions and annealing temperatures. In this study, VOx nanopowders were prepared by hydrothermal method, and annealing-induced characterizations of VOx were analyzed. The morphologies, structures, composition, and optical properties of VOx were characterized by SEM, XRD, EDX, FTIR, and UV–Vis spectroscopy. The results demonstrated that the annealing temperature significantly affected the transition of oxide states from the VOOH and VOx clusters to V2O5 nanoparticles and the crystal size from amorphous to 38.96 nm which led to an increase in the optical band gap from 2.28, 2.26 to 2.39 and 2.38 eV as increasing calcination temperature and enhanced photocatalytic activity under sunlight irradiation. The energy dispersive X-ray (EDX) spectra reveal that the percentage molar mass between vanadium and oxygen changes due to the oxidation state transition and the formation of oxygen vacancies in V2O5. The relation between nanoparticle size, oxidation state, and crystal size was clarified by comparing EDX and XRD spectra.

This study focused on the development of vanadium-based catalysts for formic acid production from glucose. The influence of different vanadium precursors on the catalytic activity of titania supported catalysts was contemplated and compared to the performance of commercial and synthesized unsupported V 2 O 5 . The obtained results reveal a successful deposition of multiple vanadium species on TiO 2 as confirmed by XRD, Raman, and UV-Vis measurements. Catalyst screening identifies V 5+ species as main player indicating its important oxidizing potential. Afterwards, the key reaction conditions, as temperature, time, pressure and catalyst loading, were optimized as well as the state of the catalyst after the reaction characterized.

Aqueous zinc-ion batteries (ZIBs) have attracted burgeoning attention and emerged as prospective alternatives for scalable energy storage applications due to their unique merits such as high volumetric capacity, low cost, environmentally friendly, and reliable safety. Nevertheless, current ZIBs still suffer from some thorny issues, including low intrinsic electron conductivity, poor reversibility, zinc anode dendrites, and side reactions. Herein, conductive polyaniline (PANI) is intercalated as a pillar into the hydrated V2O5 (PAVO) to stabilize the structure of the cathode material. Meanwhile, graphene oxide (GO) was modified onto the glass fiber (GF) membrane through simple electrospinning and laser reduction methods to inhibit dendrite growth. As a result, the prepared cells present excellent electrochemical performance with enhanced specific capacity (362 mAh g−1 at 0.1 A g−1), significant rate capability (280 mAh g−1 at 10 A g−1), and admirable cycling stability (74% capacity retention after 4800 cycles at 5 A g−1). These findings provide key insights into the development of high-performance zinc-ion batteries.

In this study, vanadium (3.5+) electrolyte was prepared for vanadium redox flow batteries (VRFBs) through a reduction reaction using a batch-type hydrothermal reactor, differing from conventional production methods that utilize VOSO4 and V2O5. The starting material, V2O5, was mixed with various concentrations (0.8 M, 1.2 M, 1.6 M, 2.0 M) of citric acid (CA) as the reducing agent and stirred for 60 min at 90 °C using a hot plate to ensure complete dispersion in the solution. The resulting solution was subsequently subjected to a hydrothermal reduction reaction (HRR) furnace at 150 °C for 24 h to generate vanadium (3.5+). The mixed states of the produced vanadium (3+) and vanadium (4+) were confirmed using UV-vis spectroscopy. The electrochemical properties of the electrolyte were investigated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), revealing that the optimal concentration of the CA was 1.6 M. The current efficiency, energy efficiency, and voltage efficiency of the electrolyte produced via the HRR process was compared with that prepared using VOSO4 in charge and discharge experiments. The results demonstrate that the HRR process yields an enhanced electrolyte across all efficiency metrics produced through the given improved performance in all efficiencies. These findings indicate that the HRR process using citric acid can facilitate the straightforward preparation of vanadium (3.5+) electrolyte, making it suitable for large-scale production.

Membrane separation processes play a crucial role in gas separation applications, with the need for ongoing development to fulfill new needs for today's challenges. For this purpose, novel 2D nanomaterials are progressively showing promise over conventional polymer‐based membrane material, exhibiting excellent molecular transport properties. Beyond the 2D materials already studied in this field, this article presents the first gas separation performances of vanadium pentoxide membrane. Brand new in gas separation topic, 2D van der Waals nanoribbons of V2O5 are successfully synthesized and layered on an anodic aluminum oxide substrate. Gas permeation analysis of He, N2, and CO2 are performed on various membranes made from different quantities of the nanomaterial. Gas permeance results suggest a deviation from an expected Knudsen diffusion mechanism of the V2O5‐based membrane for He separation. The ideal selectivities of He/N2 and He/CO2 are compared to Robeson's upper bound for polymeric membranes. V2O5 membranes, prepared with the highest V2O5 quantity, exceeded the upper bound from 2008 for He/N2 and 2019 (the most recent) for He/CO2, demonstrating the interesting potential of V2O5 2D materials for gas separation. Membrane separation processes are essential in gas separation applications, requiring continuous development to tackle modern challenges. Novel 2D nanomaterials proved to enable excellent molecular transport properties. This study introduces gas separation performances of vanadium pentoxide nanoribbons based membranes. V2O5 membranes surpassed Robeson's upper bounds for He/N2 (2008) and He/CO2 (2019), showcasing the potential of V2O5 2D materials in gas separation.

Novel miniaturized Pb(II) paper-based potentiometric sensors are described using coumarin derivatives I and II as electroactive ionophores and nano vanadium pentoxide as a solid contact material for the sensitive and selective monitoring of trace lead ions. Density functional theory (DFT) confirms optimum geometries, electronic properties, and charge transfer behaviors of 1:2 Pb(II): coumarin complexes. The sensors are prepared by using two strips of 20 × 5 mm filter paper with two circular orifices. One orifice is coated with vanadium pentoxide (V 2 O 5 ) nanoparticles in colloidal conductive carbon as a solid-contact, covered by a PVC membrane containing coumarin ionophore to act as a sensing probe. The other orifice is treated with Ag/AgCl in a polyvinyl butyral (PVB) film, to act as a reference electrode. Sensors with ionophores (I) and (II) exhibit Nernstian slopes of 27.7 ± 0.2 and 30.2 ± 0.2 mV/decade over the linear concentration range 4.5 × 10 −7 to 6.2 × 10 −3 M and 8.5 × 10 −8 to 6.2 × 10 −3 M, with detection limits of 1.3 × 10 −7 M (26.9 ppb) and 2.1 × 10 −8 M (4.4 ppb), respectively. The sensors are satisfactorily used for accurate determination of lead ions in drinking water, lead-acid battery wastewater, and electronic waste leachates. The results compare favourably well with data obtained by flameless atomic absorption spectrometry. Graphical abstract

In this study, the vanadium pentoxide (V2O5), functionalized carbon nanotubes (f-CNT), and polypyrrole (PPy) based composites films have been prepared through a facile synthesis method and their electrochemical performance were evaluated as freestanding negative electrodes of supercapacitor. A hydrous V2O5 gel prepared by treating V2O5 powder with H2O2 was mixed with f-CNT to obtain V2O5/f-CNT composite film. V2O5/f-CNT composite was then coated with PPy through vapor phase polymerization method. The PPy deposited on the V2O5/f-CNT prevented the dissolution of V2O5 and thus resulted in an improved the capacitance and cycle life stability for V2O5/f-CNT/PPy composite electrode. V2O5/f-CNT/PPy freestanding negative electrode exhibited a high areal capacitance value (1266 mF cm−2 at a current density of 1 mA cm−2) and good cycling stability (83.0% capacitance retention after 10,000 charge-discharge cycles). The superior performance of the V2O5/f-CNT/PPy composite electrode can be attributed to the synergy between f-CNT with high conductivity and V2O5 and PPy with high-energy densities. Thus, V2O5/f-CNT/PPy composite based electrode can effectively mitigate the drawbacks of the low specific capacitance of CNTs and the poor cycling life of V2O5.

We investigate the effect of cerium and tungsten addition to optimize the deNOx activity of V2O5/TiO2 catalysts over a broad temperature range in the catalytic reduction of NOx with NH3 (NH3-SCR) with and without the presence of water. The catalysts were synthesized following co-impregnation of TiO2 with different loadings and varying content of V2O5, CeO2 and WO3 oxides as promoters. Based on surface and bulk characterization, we show that all catalysts undergo different structural changes depending on the chemical nature of the promoters. X-ray photoelectron spectra indicate a tendency for surface reduction after addition of CeO2, surface oxidation after addition of WO3, and after catalytic NH3-SCR. Promotion of V2O5/TiO2 catalysts with CeO2 and/or WO3 broadens the operation temperature window of the catalytic NH3-SCR reaction under both dry and wet conditions and improves the N2 selectivity at high temperatures. The thermal deactivation resistance of CeO2- and WO3-promoted catalysts improves with increasing amount of WO3. We tentatively relate this to suppression of the sintering of the active VOx component and increasing the amount of CeVO4. The latter, as a consequence of Ce-V interaction, detrimentally changes the surface composition of the catalysts and hides active V in the bulk structure inaccessible for reaction. Water slightly decreases the overall catalytic activity of SCR at low temperatures, while preventing the formation of N2O at elevated temperatures. Addition of CeO2 leads to a slight decrease in overall reducibility of the catalysts, while W causes an enhancement in quantitative H2 uptake. On the contrary, the sole addition of CeO2 leads to an enhancement of ammonia adsorption and the appearance of new acidic surface sites, which beneficially combine the reduced surface of the catalysts with an enhanced deNOx activity at low temperature.

Inconel 625 samples, obtained by Selective Laser Melting (SLM) and conventional technology, were tested for hot corrosion resistance against a molten mixture of Na2SO4 and V2O5. The assessments were performed in air, at 900 °C with exposure time of up to 96 h, and at 1000 °C for 8 h. Weight gain was higher for samples obtained by SLM, with 37.4% after 8 h, 3.98% after 24 h, 4.46% after 48 h, and 5.8% after 96 h at 900 °C (22.6% at 1000 °C, 8 h). Three stages of corrosion were observed, the first and last with a high corrosion rate, while the second one showed a slower corrosion rate. Corrosion behaviour depends on the morphology of the grain boundary, which can influence the infiltration of corrosive salts, and on the formation of Cr2NiO4 compound, which acts as a temporary barrier.