Vanadyl Groups Research Articles

Solvothermal synthesis and selected properties of {[Ni(dien)2]3[V6As8O26]}2+·2 Cl– featuring the small [V6 IVAs8 IIIO26]4– cluster anion

Abstract A new arsenato-polyoxovanadate with the composition {[Ni(dien)2]3[V6As8O26]}2+·2 Cl– has been crystallized under solvothermal conditions as turquoise block-like crystals. The central structural feature is the [V6 IVAs8 IIIO26]4– cluster anion, which is composed of two trinuclear {V3O11} groups consisting of three edge-sharing VO5 polyhedra. Pairs of pyramidal AsO3 moieties share a common corner forming As2O5 units, which interconnect the {V3O11} groups. One of the [Ni(dien)2]2+ complexes adopts the s-fac (Ni1) and the second complex the mer configuration (Ni2). The Cl− anion is involved in strong hydrogen bonding interactions and links the [Ni(dien)2]2+ complexes to form twelve-membered rings which host the [V6As8O26]4– cluster anions. The Hirshfeld surface analysis yields a detailed picture of the intermolecular interactions revealing clear differences for the two unique [Ni(dien)2]2+ complexes. Intermolecular contacts also include As⋯H, O⋯H and H⋯H interactions. In the electronic spectrum the bands of d–d transitions of the vanadyl group and of the Ni2+ cations overlap, preventing a detailed analysis.

Electronic and Magnetic Properties of a Monolayer of VOTPP Molecules Sublimated on Ag(100)

AbstractVanadyl(IV) 5,10,15,20‐tetraphenylporphyrin (VOTPP) is an S = 1/2 molecular system with remarkable spin qubit properties. Its structure offers a higher chemical tunability with respect to archetypal molecular qubits, such as vanadyl(IV)Phthalocyanines (VOPc), and a less rigid organic scaffold where peripheral phenyl rings can promote electron decoupling from the substrate. The properties of a VOTPP monolayer on the Ag(100) surface by photoemission spectroscopies and synchrotron radiation are studied. The results indicate that the electronic and spin features of the massive phase are retained in the monolayer. Moreover, X‐ray photoelectron spectroscopy revealed the existence of two distinct species characterized by varying strengths of molecule‐surface interactions. Like VOPc, these species can be assigned to molecules with the vanadyl group oriented upward or toward the surface. However, in contrast to VOPc, only subtle screening effects are observed in the oxygen‐down configuration, suggesting a more pronounced decoupling effect inherent in the VOTPP structure. This opens broader perspectives for investigations focusing on spin characteristics at the single‐molecule level.

Gladstone-Dale compatibility, electronic polarizability and vibrational spectroscopy of minerals and inorganic compounds with V4+O and V4+O2 vanadyl groups.

VO and VO2 vanadyl groups with short (typically 1.57-1.68 Å), essentially covalent, V-O bonds are common for V4+-bearing oxysalts with [5]- and [6]-coordinated vanadium. There is a clear negative correlation between vanadyl bond lengths and wavenumbers of the bands of V-O stretching vibrations in infrared spectra (in the range 1000-880 cm-1). Optical, structural and chemical data for vanadyl minerals are used to calculate Gladstone-Dale compatibility coefficients. Gladstone-Dale compatibility indices of minerals containing vanadyl bonds are compared with total electronic polarizabilities of V4+. Unlike compounds of [5]-coordinated Ti4+, for most minerals with V4+=O (vanadyl) bonds there is good agreement between measured refractive indices and those calculated based on the polarizability concept.

On the Origin of Ion Intercalation and Conductivity Enhancement in Sn-Doped V2O5 Cathodes of Li-Ion Batteries: A Computational Study

Vanadium pentoxide (V2O5) is one of the most promising cathode materials used in metal-ion batteries due to its high theoretical capacity. But it still suffers from low electronic conductivity leading to sluggish ion transport kinetics. Although the introduction of Sn impurities in V2O5 has been proposed to partially alleviate these drawbacks, the origin of the improvement is still unclear. In this work, we employed the density functional theory (DFT+U) method to study the role of Sn doping on the enhanced electronic conductivity and Li intercalation. Using a thermodynamic model based on defect formation energies and charge neutrality constraint, we find that Sn substitution at a vanadyl group (SnVO) is likely to occur upon Sn doping. The SnVO defect generates one electron polaron at the nearby V center, which could escape the defect site upon thermal excitation with a barrier of 0.55 eV. Such a relatively mobile polaron could act as a charge carrier and enhance the electronic conductivity of the cathode. Upon Li intercalation, the SnVO defect with a repulsive nature toward Li serves as a nucleation center, where Li could accumulate nearby the defect site. This could enhance the formation of a lithiated phase during the early discharge process. However, loading too much Sn could lead to inferior cathode performance since it impedes Li diffusion. Our findings provide insights into the role of Sn doping in the design of high-performance V2O5-based cathode materials for Li-ion batteries.

New As-Rich Arsenato-Polyoxovanadate Clusters: Solvothermal Synthesis and Selected Properties of [V6IVAs8IIIO26]4− Cluster-Containing Compounds

Three new arsenato-polyoxovanadates with the composition [M(en)3]2[V6As8O26] (M = Co2+ (I), Zn2+ (II), and Cd2+ (III)) were synthesized under solvothermal conditions in high yields, thus significantly enhancing the knowledge of As-rich polyoxovanadate cluster chemistry. The compounds are isostructural and feature the very rare [V6IVAs8IIIO26]4− cluster anion. The cluster shell is constructed by interconnection of two trimeric {V3O11} groups consisting of three edge-sharing VO5 polyhedra and four As2O5 units, which are formed by two corner-sharing AsO3 pyramids. While the As2O5 group is a common structural feature in arsenato-polyoxovanadates, the {V3O11} unit is only observed in V-rich high-nuclear heteroatom-containing polyoxovanadates {V14E8} (E = As, Sb, Ge). The complexes adopt the Λ (δδδ) conformation, which is the most stable arrangement. Interestingly, the unit cell parameters do not scale with the volume of the [M(en)3]2+ complexes, assuming a constant volume of the anion. Only a very detailed Hirshfeld surface analysis revealed that the van der Waals volume of the {V6As8O26} moiety is the smallest for the Cd-containing compound, while the volumes of the anions in the other two compounds are very similar. Therefore, the observed trends of the lattice parameters can be explained on the basis of these findings. Furthermore, intermolecular interactions include As⋯H contacts in addition to O⋯H and H⋯H interactions. The electronic spectrum of I contains d–d transitions of the vanadyl group and of the Co2+ cation. As expected only the d–d transitions of the VO2+ unit occur for II and III.

Mössbauer spectroscopy and other structural properties of some V2O5.SrO.FeO glasses

ABSTRACT A series of (80-x)%V2O5·(x)%SrO·20%FeO glasses with 0 ≤ x ≤ 40 mole are prepared. The XRD proved the amorphous network of the glasses. Some isolated V = O vanadyl groups and some V–O–V bonds are broken by the Sr ions to form V–O–Sr bridges. A continuous increase in the Tg, Tc, Tm with increasing the mol%SrO is observed . High QS, IS and LW values are detected by Mössbauer spectroscopy. Most iron ions in the samples 0 and 5 mol% SrO appeared in paramagnetic glassy phase. All the iron ions in the glasses containing from 10 to 40 mole% SrO are dissolved in glass network. An increase in the density from 3.2 to 4.2 g.cm3 with a continuous decrease in the molar volume are found with increasing the SrO%. Molar polarisability, molar refractive index in addition to some structural and optical properties are calculated and discussed.

Mn2+ substitution within the {V14As8} polyoxovanadate archetype results in {Mn2V12As8} shells with trans‐positioned heterometal positions

AbstractSolvothermal exploration of the As, V, Mn reaction system in the presence of aqueous diethylenetriamine (=dien) solution led to the discovery of [MnII4VIV12AsIII8O40(dien)4(H2O)] ⋅ 3.5H2O, containing the first arsenato‐polyoxovanadate featuring a {Mn2V12As8O40} cluster shell. In comparison to its parental {V14As8O42} archetype, two vanadyl (VO2+) units at opposite ends of the polyoxovanadate shell here are substituted by Mn2+ centers. In the solid state, these {Mn2V12As8O40} units are joined into rods by sharing common Mn−O−V linkages. Expansion of the cluster shell by two further Mn2+ sites via Mn−O=V bridges generates a {Mn4V12As8O40} moiety. Three Mn2+ cations are joined by monodentate‐coordinating dien ligands, which link the rods into layers. The dien ligands here coexist in three different coordination modes: monodentate, bidentate and tridentate, which is rarely observed. Magnetic susceptibility measurements show the expected significant antiferromagnetic coupling interactions between all spin centers present in the title compound, namely the isotropic spin‐5/2 Mn2+ centers and the isotropic spin‐1/2 vanadyl groups, in line with most other heterometal‐substituted arsenato‐polyoxovanadate(IV) clusters.

Electron stimulated desorption of vanadyl-groups from vanadium oxide thin films on Ru(0001) probed with STM.

Low-temperature scanning tunnelling microscopy (STM) is employed to study electron-stimulated desorption of vanadyl groups from an ultrathin vanadium oxide film. The vanadia patches are prepared by reactive vapour deposition of V onto a Ru(0001) surface and comprise a highly ordered network of six and twelve membered V-O rings, some of them terminated by upright V[double bond, length as m-dash]O groups. The vanadyl units can be desorbed via electron injection from the STM tip in a reliable fashion. From hundreds of individual experiments, desorption rates are determined as a function of bias voltage and tunnelling current. Data analysis reveals a distinct threshold behaviour with bias onsets at +3.3 V and -2.6 V for positive and negative polarity, respectively. The desorption rate varies quadratically (cubically) with the tunnelling current at positive (negative) sample bias, indicating that V[double bond, length as m-dash]O desorption is a many-electron process. Based on our findings, a mechanism for desorption is proposed that includes resonant tunnelling into anti-bonding or out of bonding orbitals, followed by vibrational ladder climbing in the binding potential of the V[double bond, length as m-dash]O ad-system. The underlying electronic states can be identified directly in the STM conductance spectra taken on the oxide surface.

An investigation on geometry and metal interactions in multi metallic porphyrin complexes – EPR studies [microwave power saturation and degree of covalency

Innovative stylish materials can be synthesized and designed at the molecular level by attaching well characterized and tailored functionalities that have various applications. A series of meso-tetracuperated porphyrin-Schiff base complexes has been prepared from metallo-5,10,15,20-tetrakis(4-hydroxyphenyl) porphyrins (M = Cu(II), VO(II) and Ni(II)) and salicylideneamino-2-(N,N-dimethylamino)ethane copper(II) perchlorate under a nitrogen atmosphere and their electron paramagnetic resonance (EPR) spectra have been studied. The steric hindrance and electronic effects of the substituted groups and the characteristics of the different metal ions are the major patrons in inducing the properties of the compounds. From detailed spectral analysis and complete simulation, the results reveal a dipolar interaction between the central copper metal ion of the porphyrin and the meso-copper ions, but no interaction between the vanadyl group and the meso-copper ions. Through studying the EPR properties of these compounds, it is clear that novel EPR oximetry materials can be found and this will help to extend the applications of EPR in vivo.

Improving performance of polymer-based ammonia gas sensor using POMA/V2O5 hybrid films

Abstract Conducting polymers such as polyaniline (PANi) have been widely investigated as ammonia gas sensors due to their intrinsic redox states, good environmental stability, and suitability for low-cost and variable changing in electrical conductivity when exposed to acid and basic gases. In this paper we used both a hybrid PANi derivative, poly(o-methoxyaniline) (POMA)-vanadium pentoxide (V2O5) film, and new ac electrical measurement strategies to increase the ammonia gas sensor performance. Complex impedance measurements of POMA/V2O5 hybrid film showed linearity in response and a high sensitivity to ammonia in the 0–20 ppm range in both real (around 800%) and imaginary (around 3000%) components, which indicated that the film is a good candidate to use as an ammonia sensing material. FTIR spectra presented typical V2O5 and POMA bands and also presented a shifting to higher wave numbers in bands referring to the vanadyl group and primary amines, which indicated the presence of hydrogen bonds between oxide and polymer. Finally, the Cole–Cole theoretical model with an interface effect provided a good fit for the experimental results from electrical ac measurements.

Thermal activation and aging of a V2O5/WO3-TiO2 catalyst for the selective catalytic reduction of NO with NH3

Real-world vanadium-based catalysts for the selective catalytic reduction (SCR) of NO with NH3 are occasionally exposed to high temperatures, which can induce catalyst aging. In this work, a 2.0 wt% V2O5/WO3-TiO2 catalyst based on commercial WO3-TiO2 was lab aged in dry and wet feed at different time lengths and temperatures. Aging carried out in static atmosphere or in flow only marginally influenced its performance, while e.g. temperature and water in the feed heavily affected the SCR activity. The low temperature NOx conversion (≤300 °C) increased after aging up to 600 °C for 16 h and was more pronounced after hydrothermal aging compared to thermal aging, which was associated with the increased surface coverage of the SCR-active vanadyl groups. Measurements of vanadium volatility in the temperature range selected for the aging temperatures revealed the high mobility of V species induced by the (hydro-)thermal treatments. The onset of catalyst deactivation, observed at lower aging temperature for the hydrothermally aged catalyst compared to the thermally treated one, is possibly due to a larger amount of mobile V and W species and the concurrent loss of specific surface area. The set of catalytic and characterization data showed that water is an essential component in aging protocols because it heavily affects the structure and the resulting catalytic activity of the SCR catalyst. Removal of residual sulfate groups, which are present on the commercial support, also contributed to catalyst activation at 550°C aging temperature as a result of structural changes evidenced by surface area measurements and by IR and Raman spectroscopy, including rearrangement of V species and apparent increase of Lewis acidity.

Dehydration of microporous vanadosilicates: the case of VSH-13Na

Microporous VSH-13Na of composition Na2(VO)(Si4O10)·3H2O was synthesized under mild hydrothermal conditions and studied by single-crystal X-ray diffraction at room temperature and 398 K. Its vanadosilicate framework, consisting of sheets of silicate tetrahedra connected by vanadyl-type square-based pyramids, closely resembles that of the mineral cavansite, Ca(VO)(Si4O10)·4H2O. Due to the disorder in the orientation of the short apical vanadyl groups, the topological symmetry of VSH-13Na was originally described in space group Imma. However, when analysing the systematic absences in our dataset, only the 21 screw axis along b was strictly fulfilled suggesting monoclinic space group P1211. The resulting structure in P21 with a = 14.364 (4), b = 9.134 (2), c = 10.373 (3) Å, β = 90.056 (7)°, V = 1360.9 (7) Å3 was interpreted as a case of allotwinning of two polytypes with topologically idealized orthorhombic symmetry: A (∼62%) with antiparallel orientation of the vanadyl groups in adjacent (100) layers and B (∼38%) with all vanadyl groups in adjacent layers oriented in the same way. At 398 K, the structure of VSH-13Na became fully dehydrated and adopted the unit-cell parameters a = 12.584 (16), b = 9.525 (13), c = 9.696 (14) Å, β = 90.10 (4)°, V = 1162 (3) Å3 (space group P21). Release of H2O caused severe contraction of T—O—T angles and the unit-cell volume decreased by ∼15%. Despite their structural similarity, the VSH-13Na framework seems to be more flexible upon dehydration compared with cavansite, whose structure collapsed before removal of the last H2O molecule. Thus, the presence of monovalent or divalent extraframework cations plays a key role in the dehydration process of natural and synthetic vanadosilicates.

Evaluation of Gastroprotective Effect of Vanadyl Sulfate and Lycopene on rat model with Ethanol-Induced Gastric Mucosal Lesions

Gastric ulcers result from an imbalance between endogenous defense mechanisms and certain aggressive agents. Many drugs were used to overcome this imbalance, but few literatures made on plants. Therefore, we try to evaluate the gastroprotective efficacy of two nutritional supplements (Vanadyl sulfate and Lycopene) in comparison to Lansoprazole. Five groups of seven healthy albino male rats each were received an oral daily dose of above agents for ten days. Then 1.25 ml of 95% ethanol orally used to induce mucosal injury and animals were sacrificed 1 hour later. Glutathione and malondialdehyde were estimated. A significant elevation in glutathione level found in Vanadyl and Lycopene-received groups in comparison to lansoprazole-received group (717.13±19.47 μmol/gm wet tissue, 609.55±17.6 μmol/gm wet tissue and 512.07±25.32 μmol/gm wet tissue respectively), with a significant reduction in malondialdehyde level (10.63±0.92 nmol/gm wet tissue, 12.66±0.56 nmol/g wet tissue and 14.90±0.33 nmol/gm wet tissue respectively). This revealed gastro-protective effects of Vanadyl and Lycopene in ameliorating the oxidative cellular damage.

Unusually Strong Dipole–Dipole and Dipole–Quadrupole Interactions in a Nanoporous Solid. Crystal Structure and Related Properties of (VO)3[M(CN)6]2·nH2O (M = Fe, Co)

In porous Prussian blue (PB) analogues, the partially naked central metal atoms found at the cavities surface are responsible for many of their physical properties, among them the adsorption potentials. In the as‐synthesized PB analogues, such metal sites stabilize water molecules inside the cavity through coordination bond formation. The filling of the cavity volume is completed with water molecules linked to the coordinated ones through hydrogen bonds formation. Vanadyl‐based PB analogue shows quite different features. The metal(V) at the cavities surface has saturated its coordination sphere with the O atom of the vanadyl ion (V=O). In this material, the V=O group preserves enough strong dipole moment to stabilize adsorbed species at the cavity through dipole–dipole and dipole–quadrupole interactions. This contribution reports the preparation, crystal structure and properties for (VO)3[M(CN)6]2·nH2O (M = Fe, Co). According to the refined crystal structure, IR spectra and TG data, six water molecules remain stabilized inside the cavities through a strong dipole–dipole coupling with the vanadyl group. The cavity contains additional water molecules interacting through hydrogen bond bridges with the water molecules coupled to the V=O group. The vanadyl ion is free of hydrogen bonding interactions with the water molecules. The recorded adsorption isotherms for N2, CO2 and H2, three molecules with only quadrupole moment, reveal presence of relative strong adsorption forces due to dipole‐quadrupole interactions.

Configurational Isomerism in Polyoxovanadates.

A water-soluble derivative of the polyoxovanadate {V15 E6 O42 } (E=semimetal) archetype enables the study of cluster shell rearrangements driven by supramolecular interactions. A reaction unique to E=Sb, induced exclusively by ligand metathesis in peripheral [Ni(ethylenediamine)3 ]2+ counterions, results in the formation of the metastable α1 * configurational isomer of the {V14 Sb8 O42 } cluster type. Contrary to all other polyoxovanadate shell architectures, this isomer comprises an inward-oriented vanadyl group and is ca. 50 and 12 kJ mol-1 higher in energy than the previously isolated α and β isomers, respectively. We discuss this unexpected reaction in light of supramolecular Sb-O⋅⋅⋅V and Sb-O⋅⋅⋅Sb contacts manifested in {V14 Sb8 O42 }2 dimers detected in the solid state. ESI MS experiments confirm the stability of these dimers also in solution and in the gas phase. DFT calculations indicate that other, as of yet elusive isomers of {V14 Sb8 }, might be accessible as well.

Correlations between EPR and optical properties: Diborovanadate glasses in a highly modified regime

Glasses with composition x V2O5 - 10PbO – (90−x) NaBO2 with 10≤x≤30 were prepared by a novel, energy-efficient and economical microwave method. The Electron Paramagnetic Resonance (EPR) spectra of all the glasses investigated exhibited a well-defined hyperfine structure, from which the spin Hamiltonian parameters of the VO2+ ion, dipolar hyperfine coupling parameters, and the fermi-contact interaction term (K) have been calculated. The values of g-tensor reveal the existence of the VO2+ ion in octahedral coordination with a tetragonally compressed site. The variations seen in P, K, Pβ2K and PK/γ with V2O5 content indicate the s character of the magnetic spin of vanadium which arises due to the partial unpairing of s-electrons. Also, a decrease in K with V2O5 mol% suggests a strong VO interaction, makes the bond length (VO) in the vanadyl group shorter and distorts the vanadyl group from Oh to C4V. The EPR and UV–Vis parameters are analyzed on the basis of structural motifs formed due to the network modification. The molecular orbital coefficients α2 and γ2 have been calculated. The ratio, 1−γ21−α2 increases with increasing V2O5 mol%, suggesting that the σ-bonding between the V atom and the equatorial ligand is weakening. IR studies reveal the presence of [BO3/2]0, [BO4/2]− and [B2V2O9]2− structural groups in the glass matrix.

Formic acid decomposition over V-Ti oxide catalyst: Mechanism and kinetics

A detailed kinetic model for formic acid (HCOOH) decomposition on oxide vanadium-titanium (7.3%V2O5/92.7%TiO2) catalyst has been developed based on transient kinetic studies and IR spectroscopy in situ. Formic acid decomposition to CO2 (dehydrogenation) and to CO (dehydration) proceeds via different mechanistic routes. Dehydrogenation proceeds via the conventional “formate” mechanism and include reversible dissociative adsorption of formic acid on vanadyl group V=O. The oxygen of the group acts as a proton acceptor whereas a vanadium cation is a formate anion stabilizer. Formate complexes can recombinate with protons and desorb in the form of formic acid or decompose to CO2. Dehydration reaction follows a different mechanism. An interaction of the coordination unsaturated sites V+-O− with HCOOH leads to the synchronous cleavage of the COH and CH bonds. Meanwhile the two OH hydroxyl groups are formed and CO molecule is evolved into gas phase. The path is completed by water desorption.The rate constants and activation energies of elementary steps are calculated for a dehydrogenation and dehydration reactions. The rate-limited steps of the reaction are formate decomposition stage for dehydrogenation path (Ea=60kJ/mol) and water desorption stage for dehydration rout (Ea=100kJ/mol). The difference in the values of activation energies results in an increase of selectivity towards CO with reaction temperature elevation. Water inhibits formic acid decomposition. In the case the dehydrogenation, it connected with adsorption displacement of formates with water, whereas, in the case of dehydration, it is associated with an active centers blocking by adsorbed water. The developed kinetic model takes into account the water effect of both routs and satisfactorily describes the steady state reaction behavior.

Nanobelt-arrayed vanadium oxide hierarchical microspheres as catalysts for selective oxidation of 5-hydroxymethylfurfural toward 2,5-diformylfuran

Nanobelt-arrayed vanadium oxide hierarchical microspheres were synthesized to catalyze selective oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran with the high conversion and selectivity of 93.7% and 95.4%, respectively. This prominent performance can be attributed to the major exposure of (010) facet with highest hydrogen adsorption capability of vanadyl group (VO) sites and the highly oriented morphology for reactant contact and residence time control. Density functional theory calculation of the hydrogen adsorption capabilities on different facets and different chemical environmental sites has been utilized to explain the influence of different facets and lattice oxygen sites on 5-hydroxymethylfurfural oxidation performance based on hydrogen adsorption and αH-C bond cleavage steps. Isotopic studies verified the reaction mechanism and kinetic studies derived the first order reaction rate equation dependent on the 5-hydroxymethylfurfural concentration. These results suggested the crucial roles of (0 1 0) facets and the VO sites in O-H and αH-C bonds cleavage of 5-hydroxymethylfurfural before the reduction product V-OH species further dehydrogenation by molecular oxygen.

Effect of Variable Oxidation States of Vanadium on the Structural, Optical, and Dielectric Properties of B2O3-Li2O-ZnO-V2O5 Glasses.

In the present study, the effect of variable vanadium oxidation states on the structural, optical, and dielectric properties of vanadium oxide containing lithium borate glasses has been investigated. Electron paramagnetic resonance studies indicate that vanadium in these glasses is mostly in the V4+ state, having a tetragonal symmetry. As the glass composition of V2O5 increases, tetragonality also increases at the cost of octahedral symmetry. The photoluminescence (PL) spectra of these glasses are dominated by zinc oxide transition, whereas the peaks pertaining to the vanadyl group are not visible in the PL spectra. The optical absorption spectra show a single wide absorption band, which is attributed to V4+ ions in these glasses. The ac conductivity of the glasses increases with an increase in vanadium content. The highest electrical conductivity observed is ∼10-5 S cm-1 at 250 °C for the glass with 2.5 mol % V2O5. Electrical conductivity is dominated by electron conduction, as indicated by the activation energy calculation.

Mo3VOx catalyst in biomass conversion: A review in structural evolution and reaction pathways

Mo3VOx heterogeneous catalyst is among the complex metal oxides that have piqued recent interest due to its superior ýcatalytic properties. Its synthesis via sol gel or hydrothermal methods focused on the production of pentagonal polyoxomolybdate unit in the reaction precursor assembles with other V and Mo ions to form crystalline MoV oxides with pentagonal, hexagonal, and heptagonal units in either trigonal or orthorhombic phases. Moreover, the orthorhombic structure of Mo3VOx catalyst exhibited particularly high catalytic activity for selective oxidation of ethane, propane, and acrolein, whereby the reaction can take place not only in the mouth of heptagonal channels, but also in the entirety of the Mo3VO4 channel. Indeed, the Vanadyl groups with vanadium at the crystallographic positions are accountable for C–H activation of propane in the rate determining abstraction of the first H2 atoms. The molybdenum surface enrichment is detrimental with respect to the selectivity of the reaction. With that advantage, Mo3VOx has been applied as a catalyst for the acrolein oxidation to acrylic acid, selective oxidative activation of alkanes, ammoxidation of propane to acrylonitrile, or to acrylic acid, oxidation of n-butane to maleic acid or anhydride, oxidative of dehydrogenation of ethane to ethylene, or oxidation of ethane to acetic acid and partial oxidation of alcohols/aromatic hydrocarbon. Abundant metal components, such as Fe, W, Cu, Nb, and Te, have been used with the intention of optimizing the structure and catalytic performance, elucidating structural peculiarities, and improving catalytic performance.