V2O5 Catalysts Research Articles

Novel bilayer 2D V2O5 as a potential catalyst for fast photodegradation of organic dyes

Two-dimensional (2D) materials have recently drawn interest in various applications due to their superior electronic properties, high specific surface area, and surface activity. However, studies on the catalytic properties of the 2D counterpart of V2O5 are scarce. In the present study, the catalytic properties of 2D V2O5 vis-à-vis bulk V2O5 for the degradation of methylene blue dye are discussed for the first time. The 2D V2O5 catalyst was synthesized using a modified chemical exfoliation technique. A massive increase in the electrochemically active surface area of 2D V2O5 by one order of magnitude greater than that of bulk V2O5 was observed in this study. Simultaneously, ~ 7 times increase in the optical absorption coefficient of 2D V2O5 significantly increases the number of photogenerated electrons involved in the catalytic performance. In addition, the surface activity of the 2D V2O5 catalyst is enhanced by generating surface oxygen vacancy defects. In the current study, we have achieved ~ 99% degradation of 16 ppm dye using the 2D V2O5 nanosheet catalysts under UV light exposure with a remarkable degradation rate constant of 2.31 min−1, which is an increase of the order of 102 from previous studies using V2O5 nanostructures and nanocomposites as catalysts. Since the enhanced photocatalytic activity emerged from the surface and optical properties of the catalyst, the current study shows great promise for the future application of 2D V2O5 in photo- and electrocatalysis.

Graphene controlled solid-state growth of oxygen vacancies riched V2O5 catalyst to highly activate Fenton-like reaction

Fenton-like process based on metal oxide presents one of the most hoping strategies to generate reactive oxygen species to treat refractory pollutants. The introduction of oxygen vacancies (OVs) can enhance the catalytic performance of metal oxides in Fenton-like reaction. In this paper, a one-step all solid-state synthesis strategy is proposed to induce oxygen defects in V2O5, which uses graphene to engineer the crystallization process of V-based crystals. Such approach employs graphene as a solid-catalyst to promote growth of V-based crystals owing to the ions-π interactions between graphene and VCl3. The electron-donor OVs in V2O5@graphene can not only active H2O2 for the •OH generation, but also accelerate the reduction of V5+ and V4+, thereby ensuring defective V2O5@graphene/H2O2 system is 14.3, 28.2, and 17.3 times higher than that of graphene/H2O2, pure V2O5/H2O2 and graphene+V2O5/H2O2 (mechanical mixed system), respectively. Our study provides a novel synthetic strategy to design and prepare OVs-riched transition metal catalysts for developing advanced oxidation technologies toward higher sustainability and practicality.

Lewis Acid Fe‐V Pairs Promote Nitrate Electroreduction to Ammonia

AbstractElectrochemical reduction of nitrate to ammonia (NO3RR) has been recognized as an appealing approach to realize both sustainable NH3 production and waste nitrate removal. Herein, from the perspective of Lewis acid‐base interaction, a single‐atom Fe‐doped V2O5 (Fe‐V2O5) catalyst enriched is designed with Lewis acid sites, which present the maximum NH3‐Faradaic efficiency of 97.1% with the corresponding NH3 yield of 12.5 mg h−1 cm−2 at –0.7 V versus RHE. Mechanistic studies based on theoretical calculations and operando spectroscopic characterizations identify the creation of Lewis acid Fe‐V pairs on Fe‐V2O5, which can synergetically activate the NO3−, promote the hydrogenation energetics, and restrain the hydrogen evolution, leading to the enhanced NO3RR activity and selectivity.

Photocatalytic Activity of the V2O5 Catalyst toward Selected Pharmaceuticals and Their Mixture: Influence of the Molecular Structure on the Efficiency of the Process.

Due to the inability of conventional wastewater treatment procedures to remove organic pharmaceutical pollutants, active pharmaceutical components remain in wastewater and even reach tap water. In terms of pharmaceutical pollutants, the scientific community focuses on β-blockers due to their extensive (over)usage and moderately high solubility. In this study, the photocatalytic activity of V2O5 was investigated through the degradation of nadolol (NAD), pindolol (PIN), metoprolol (MET), and their mixture under ultraviolet (UV) irradiation in water. For the preparation of V2O5, facile hydrothermal synthesis was used. The structural, morphological, and surface properties and purity of synthesized V2O5 powder were investigated by scanning electron microscopy (SEM), X-ray, and Raman spectroscopy. SEM micrographs showed hexagonal-shaped platelets with well-defined morphology of materials with diameters in the range of 10−65 µm and thickness of around a few microns. X-ray diffraction identified only one crystalline phase in the sample. The Raman scattering measurements taken on the catalyst confirmed the result of XRPD. Degradation kinetics were monitored by ultra-fast liquid chromatography with diode array detection. The results showed that in individual solutions, photocatalytic degradation of MET and NAD was relatively insignificant (<10%). However, in the PIN case, the degradation was significant (64%). In the mixture, the photodegradation efficiency of MET and NAD slightly increased (15% and 13%). Conversely, it reduced the PIN to the still satisfactory value of 40%. Computational analysis based on molecular and periodic density functional theory calculations was used to complement our experimental findings. Calculations of the average local ionization energy indicate that the PIN is the most reactive of all three considered molecules in terms of removing an electron from it.

Synthesis, characterization, catalytic reduction of Eosin B dye and C, N cross coupling reactions of sodiumalginate/V2O5 nanocomposite

BackgroundA low cost with high efficiency sodiumalginate (SA)/V2O5 nanocomposite catalyst was synthesized by complexation followed by reduction method. The V2O5 catalyst and SA was chemically linked with each other and hence restriction in diffusion of the catalyst into the reaction medium during the course of the reaction. The catalytic activity of SA/V2O5 bio-nano catalyst system was tested towards the C, N cross coupling reaction and reduction of EB dye. MethodsThe bio-polymer nanocomposite formation was confirmed by FT-IR spectroscopy, 1H-NMR spectroscopy, DSC (Tg) and TGA (Td) and HR-TEM (size) like analytical tools. The cross coupling reaction between rosebengal (RB) and nitrogen containing heterocyclic compounds like indole, benzimidazole, 2-methylimidazole were carried out. Same type of reaction was carried out with congored (CR), acidfuchsin (AF) and safranine O (SO) dyes. Further, the catalytic activity of SA/V2O5 nanocomposite catalyst was tested towards the reduction of Eosin blue (EB) dye. Significant findingsThe FTIR spectrum showed a peak at 615 cm−1 due to the V-O stretching. The 1H-NMR spectrum confirmed that the OH group of SA involved in the complex formation with V atom of V2O5. The Tg and Td of the SA/V2O5 bio-polymer nanocomposite system was higher than that of the neat polymer. The apparent rate constant (kapp) value was found to be higher in the presence of SA/V2O5 catalyst system. The C,N cross coupling reaction was successfully carried out with significant % yield in the presence of low cost and eco-friendly SA/V2O5 nano catalyst. The catalyst was stable up to several cycles of operations.

Synthesis of value-added furan compounds from biomass derived glucose via cascade catalysis using functionalized V2O5 catalysts

• Both organic and inorganic surface functionalization of V 2 O 5 NPs and their characterization have been studied. • Surface of V2O5 NPs modified with trimesic acid has led to the formation vanadium fibers are highly active in the synthesis of DFF. • Functionalized vanadia has been utilized in the one pot conversion of glucose to DFF in good yields via cascade catalysis. • The nitro alcohol product (1,1’-(furan-2,5-diyl)bis(2-nitroethan-1-ol) was synthesized directly from biomass derived glucose. In this paper we report the highly active, versatile and stable catalyst has been prepared through surface functionalization of vanadium oxide nanoparticles (V 2 O 5 NPs) using various organic modifiers. The surface modified catalyst forms fiber type of structure has been evaluated in the cascade catalysis of glucose to 2,5-diformyl furan (DFF) in water. Further, nitro alcohol product (1,1’-(furan-2,5-diyl)bis(2-nitroethan-1-ol) was synthesized by adding nitromethane and potassium carbonate to DFF formed ( in situ) from biomass. This is a new representative of work using heterogeneous catalysis utilizing surface modified NPs. High thermal stability, high crystallinity with a band gap (5.03 eV) and fibrous nature makes the surface modified catalyst attractive to recycle in DFF synthesis from glucose. In addition, orthorhombic V 2 O 5 NPs have been deposited on high surface area carbon (Vulcan XC72R) were prepared, characterized and studied in catalysis of biomass conversion.

Cobalt-doped V2O5 hexagonal nanosheets for superior photocatalytic toxic pollutants degradation, Cr (VI) reduction, and photoelectrochemical water oxidation performance

The worldwide energy calamity and ecological disturbances demand materials that can remove harmful contaminants from the polluted water. Recently, semiconductor-based catalytic dye removal has created much consideration due to its high efficacy and eco-friendly contaminated water treatment processes. Vanadium oxide (V2O5) has attracted superior attention as a catalyst due to its robust oxidation power, chemical inertness, and stability against photodegradation. In this study, pristine and cobalt (Co)-doped V2O5 samples were synthesized by solvothermal method and examined for their photo-degradation activity and photoelectrochemical (PEC) water oxidation properties. The orthorhombic crystal phase was confirmed by X-ray diffraction (XRD), hexagonal-shaped morphology was observed by scanning electron microscope (SEM) and reduced optical band gap (2.01 eV) was noticed for doped V2O5 catalyst compared to the pristine (2.20 eV) catalyst. The doped V2O5 catalyst exhibited enhanced photodegradation of crystal violet CV (92.7%) and Cr (VI) reduction (90.5%) after 100 min of light irradiation. The doped photocatalyst exhibited approximately 2.1 and 1.9-fold enhancement of photodegradation of CV and Cr(VI) reduction, respectively. The doped electrode showed improved photocurrent density (0.54 mA/cm−2) compared to pristine electrode (0.12 mA/cm−2). Moreover, the doped electrode showed reduced charge-transfer resistance and enhanced charge-transfer properties compared to those of the pristine electrode. Hence, the prepared hexagonal-shaped V2O5 is a suitable material for the elimination of environmental contaminants from the polluted water as well as water splitting for hydrogen generation.

Interface sites on vanadia-based catalysts are highly active for NOx removal under realistic conditions

TiO2-supported V2O5 catalysts are commonly used in NOx reduction with ammonia due to their robust catalytic performance. Over these catalysts, it is generally considered that the active species are mainly derived from the vanadia species rather than the intrinsic structure of V-O-Ti entities, namely the interface sites. To reveal the role of V-O-Ti entities in NH3-SCR, herein, we prepared TiO2/V2O5 catalysts and demonstrated that V-O-Ti entities were more active for NOx reduction under wet conditions than the V sites (V=O) working alone. On the V-O-Ti entities, kinetic measurements and first principles calculations revealed that NH3 activation exhibited a much lower energy barrier than that on V=O sites. Under wet conditions, the V-O-Ti interface significantly inhibited the transformation of V=O to V-OH sites thus benefiting NH3 activation. Under wet conditions, meanwhile, the migration of NH4+ from Ti site neighboring the V-O-Ti interface to Ti site of the V-O-Ti interface was exothermic; thus, V-O-Ti entities together with neighboring Ti sites could serve as channels linking NH3 pool and active centers for activation of NH4+. This finding reveals that the V-O-Ti interface sites on V-based catalysts play a crucial role in NOx removal under realistic conditions, providing a new perspective on NH3-SCR mechanism.

Polyol-Mediated Synthesis of V2O5-WO3/TiO2 Catalysts for Low-Temperature Selective Catalytic Reduction with Ammonia.

We demonstrated highly efficient selective catalytic reduction catalysts by adopting the polyol process, and the prepared catalysts exhibited a high nitrogen oxide (NOX) removal efficiency of 96% at 250 °C. The V2O5 and WO3 catalyst nanoparticles prepared using the polyol process were smaller (~10 nm) than those prepared using the impregnation method (~20 nm), and the small catalyst size enabled an increase in surface area and catalytic acid sites. The NOX removal efficiencies at temperatures between 200 and 250 °C were enhanced by approximately 30% compared to those of the catalysts prepared using the conventional impregnation method. The NH3-temperature-programmed desorption and H2-temperature-programmed reduction results confirmed that the polyol process produced more surface acid sites at low temperatures and enhanced the redox ability. The in situ Fourier-transform infrared spectra further elucidated the fast absorption of NH3 and its reduction with NO and O2 on the prepared catalyst surfaces. This study provides an effective approach to synthesizing efficient low-temperature SCR catalysts and may contribute to further studies related to other catalytic systems.

Toward rational design of supported vanadia catalysts of lignin conversion to phenol

In sustainable chemical engineering, catalytic upgrading of lignocellulosic biomass has recently gained attention for producing renewable platform chemicals. To achieve maximal biomass utilization, upgrading the underutilized lignin components is essential. Among various catalysts for lignin upgrading, supported vanadia (V2O5) catalysts are promising because of their cost-effectiveness and tunability of either dopant metals or catalyst supports. Here, computational studies are conducted to derive rational design guidelines of supported V2O5 catalysts for accomplishing the high catalytic activity of lignin upgrading to phenol, a key compound for producing bioplastics and biofuel blendstocks. Guaiacol was used as the model compound since it comprises the highest portion of depolymerized lignin. Computational mechanistic studies for the catalytic guaiacol conversion to phenol were performed for the V2O5 catalysts on Titania (TiO2) and silica (SiO2) to explain higher experimental phenol yields on V2O5/SiO2 than V2O5/TiO2. The hydrogen migration from the methoxy group to the aryl ring was identified as a rate-determining step, and the overall activation energies on the two catalysts were compared. A structural analysis was carried out for the catalysts and rate-determining transition states to gain further insights from mechanistic studies. It was concluded that the tilt angle of the aryl group in the hydrogen migration transition state is a key descriptor determining the catalytic activity of phenol formation. These features correlate well with activation energies and experimental phenol yields, indicating that they provide design guidelines for supported metal catalysts for lignin upgrading before experiments.

Application of CeO2-V2O5 catalysts in the oxidative desulfurization of 4,6-dimethyl dibenzothiophene as a model reaction to remove sulfur from fuels

Oxidative desulfurization (ODS) is an excellent alternative for removing sulfur from fuels and the accurate choice of catalyst is essential in obtaining good conversion. In this study, V2O5 and CeO2 catalysts and their mixture were prepared by incipient impregnation method from ammonium metavanadate and cerium chloride as precursors. The catalysts were characterized by different physicochemical techniques. The acidity of the catalyst was measured potentiometrically by titration with pyridine and using a platinum electrode. The catalytic properties of the synthesized catalysts were evaluated in the ODS of 4,6-dimethyl dibenzothiophene. Acidity increased with the addition of vanadium, which generated more variants in the oxidation state of V2O5 and improved the catalytic activity. The vanadium catalyst with the highest amount of vanadium oxide achieved a conversion rate of nearly 100%, renders a viable catalyst for sulfur removal. Factors such as acidity and surface area affect the catalytic activity.

Removal of vanadium by ion exchange resins from model and real solutions from spent V2O5 catalyst

The present study deals with the potential application of the two adsorbents Dowex M4195 (M4195) and Lewatit MonoPlus TP220 (TP220) for the removal of vanadium(V) from the model and real aqueous solutions. The kinetic and equilibrium studies as well as the effects of pH, ion exchanger dose, contact time and initial concentration were studied using the batch method. Both the Langmuir and Freundlich adsorption isotherms and the pseudo-first order, pseudo-second order, intraparticle diffusion kinetic models were used to describe the adsorption process. The maximum adsorption capacity obtained from the Langmuir isotherm was found to be 248 mg/g and 209 mg/g for TP220 and M4195, respectively. The kinetics followed the pseudo second order reaction. Desorption, reusability of ion exchangers and vanadium(V) removal in the continuous system (column studies) were determined.

Degradation of o-, m-, p-cresol isomers using ozone in the presence of V2O5-supported Mn, Fe, and Ni catalysts

Abstract Oxidative degradation of o-, m- and p-cresols using ozone in the presence of V2O5-supported metal (Mn, Fe, Ni) catalysts was studied under ambient reaction conditions. Metal (Mn, Fe, Ni) loaded V2O5 catalysts were prepared using a wet-impregnation method, thereafter, characterized, and analyzed by use of the XRD, FT-IR, SEM-EDX, TEM, and ICP-OES. Results show the effect of the amount of a metal that was loaded on the support, particularly, how it affects the resultant catalysts’ (i) crystallite size, (ii) dispersion of an active metal over the surface of a support, and (iii) catalytic activity. Mn-loaded catalysts were found to be relatively more active for the conversion of individual cresol isomers and the activity of this catalyst was significantly enhanced at a lower Mn to V2O5 ratio (2.5 wt%). Mn(2.5 %)/V2O5 catalyst led to conversions of 66.78, 71.01 and 73.68 % with o-, m-, and p-cresols respectively within 24 h of oxidation. Oxidation products were derivatized by ethanol and a few were positively detected using GC-MS. o-Tolyl acetate and 2,5-dihydroxy toluene were detected from o-cresol, m-tolyl acetate, and 2,3-dihydroxy toluene from m-cresol and p-tolyl acetate and 3,4-dihydroxy toluene from p-cresol oxidation. Dimethyl maleate and dimethyl oxalate were detected as common products in all three isomers’ oxidation.

Transesterification of Ethyl-10-undecenoate Using a Cu-Deposited V2O5 Catalyst as a Model Reaction for Efficient Conversion of Plant Oils to Monomers and Fine Chemicals.

Transesterification of ethyl-10-undecenoate (derived from castor oil) with 1,4-cyclohexanedimethanol over a recyclable Cu-deposited V2O5 catalyst afforded 1,ω-diene, the corresponding cyclohexane-1,4-diylbis(methylene) bis(undec-10-enoate), a promising monomer for the synthesis of biobased polyesters, in an efficient manner. Deposition of Cu plays an important role in proceeding the reaction with high selectivity, and both the activity and the selectivity are preserved for five recycled runs by the addition of the substrates. The present catalyst was effective for transesterification with other alcohols, especially primary alcohols, demonstrating a possibility of using this catalyst for efficient conversion of plant oil to various fine chemicals.

Understanding the role of Al2O3-ZrO2 mixed oxides as support for vanadium catalysts for the selective ammoxidation of o-chlorotoluene to o-chlorobenzonitrile

o-Chlorotoluene (o-CT) ammoxidation to prepare o-chlorobenzonitrile (o-CBN) was investigated on Al2O3-ZrO2 supported V2O5 catalysts in the temperature range of 360 to 420 °C. A set of vanadium oxide supported on mixed oxides with varying its loadings were prepared by wet impregnation method. The catalysts surface and structural characteristics were derived from BET-surface area, X-ray diffraction, FT-infrared, temperature programmed reduction, temperature programmed desorption of ammonia and UV–Vis diffuse reflectance spectroscopy. The characterization results revealed that vanadium species were well dispersed and strongly interacted with mixed oxide support. The ammoxidation activity was depended on V2O5 content and its nature of surface species existing in the catalyst. The catalyst with 10 wt% of V2O5 on Al2O3-ZrO2 showed high ammoxidation activity with 100% selectivity to o-CBN. Moreover, the catalyst showed consistent activity during time on stream study.

Physicochemical Properties of MoVTeNb Mixed Oxide Catalysts Synthesized using Different Vanadium Sources

The use of different vanadium sources in the synthesis of multi-metal MoVTeNb oxide catalysts has been investigated for their effect on the physicochemical properties of catalysts. Metal oxides were synthesized by slurry method assisted with a microwave irradiation. Vanadium pentoxide (V2O5), vanadyl sulphate (VOSO4) and ammonium metavanadate (NH4VO3) were used as the vanadium sources, respectively. X-ray diffraction (XRD) pattern showed the existence of orthorhombic (M1) phases in all catalysts. The catalyst prepared using V2O5 produced the highest formation of the phase. This was further supported by Inductive Couple Plasma-Atomic Emission Spectroscopy (ICP-AES), which showed that the V2O5 catalyst has the highest V: Mo ratio, mainly responsible for the high catalytic activity. Temperature Programmed Reduction in Hydrogen (H2-TPR) showed better reducibility for the catalyst when compared to the others. Temperature Programmed Reaction (TPRn) confirmed that the oxidants active for propane conversion into acrylic acid were originated from the lattice of the catalyst.

Activation of film growth on indium phosphide by pulsed photon treatment

Photon activation of various physicochemical processes by the radiation of powerful pulsed xenon lamps (radiation range of 0.2-1.2 µm) is one of the promising areas of material science. The aim of this study was to determine the effect of preoxidative pulsed photon treatment on the process of thermal oxidation of indium phosphide with a nanosized layer of V2O5 on the surface, as well as its effect on the composition and morphology of the formed films. We determined the optimal mode of pre-oxidative pulsed photon treatment of magnetron-formed V2O5/InP heterostructures with a radiation density of 15 J/cm2. By laser and spectral ellipsometry methods, photon activation of V2O5/InP before thermal oxidation was found to increase the thickness of the formed films practically twofold. X-ray diffraction analysis confirms the intensification of the phosphate formation process. The morphological characteristics of the films were determined by atomic force microscopy.Pre-oxidative pulsed photon treatment with an optimal radiation density of 15 J/cm2 activates the thermal oxidation of V2O5/InP heterostructures. It is associated with the formation of new active centres and accelerated rearrangement of chemical bonds in the intermediate complexes of the V2O5 catalyst with semiconductor components

CATALYTIC ACTIVITY OF VANADIUM OXIDE DOPED WITH PALLADIUM NANOPARTICLES ON OXIDATION OF 5-HYDROXYMETHYLFURFURAL

2,5-Furan dicarboxylic acid (FDCA) is a bio-based chemical used as a feedstock for a wide range of industrial applications - particularly the bioplastic industries. It is derived from 5-hydroxymethylfurfural (HMF) through a reaction of oxidation using either homogeneous or heterogeneous catalysts. According to the advantages of heterogeneous catalysts, this research aims to seek a novel catalyst type with high selectivity and high activity. We performed an investigation of the synergic effect of palladium nanoparticles and V2O5 catalysts on catalytic oxidation of HMF and physicochemical properties. A commercial vanadium oxide powder (V2O5) was doped with 1 wt.% palladium nanoparticles (Pd NPs). The Pd NPs were prepared by the colloid-chemical reduction method. Two different synthesis processes were performed base on the consequence of the combination of colloid-chemical reduction and immobilization steps, herein stepwise (ST) and simultaneous (SI) process. For the ST process, Pd NPs were reduced and then immobilized on V2O5 powder. During the SI process, the reduction and immobilization steps took place simultaneously. Physical and chemical properties of a prepared catalyst such as morphology, particle size distribution, and chemical structure and composition were characterized using various techniques, e.g. TEM, BET, X-ray diffraction, UV-vis spectrophotometer. It was distinctly found the synergic effect between Pd NPs and V2O5 catalysts on the surface catalytic activity of HMF oxidation and catalytic selectivity. The Pd NPs incorporated catalysts (ST and SI processes) gave catalytic activity at 63%, which are 2-fold in catalytic activity in comparison with bare V2O5 catalysts as well as they were selective to FDCA up to 19-24%. The step of catalyst preparation slightly influenced on catalytic activity and yield of FDCA; however, it did alter particle size distribution of Pd NPs and surface characteristics

HCl-doping of V/TiO2-based catalysts reveals the promotion of NH3-SCR and the rate limiting role of NO oxidative activation

NH3-SCR is the best available technology for NOx abatement from power plant, incinerators, gasifiers, and a well-established technology for on board NOx emission control; in the last 40 years, the reaction mechanism and kinetics have been deeply investigated, but the understanding of the nature of surface intermediates and rate determining steps is still object of a lively discussion. A major factor, though, has been largely neglected in the scientific literature, that is the presence of HCl in the flue gases generated by coal, biomass and plastics. In this work, the effect of HCl on NH3-SCR over V2O5 catalysts was investigated through combined kinetic analysis and operando FTIR. Unexpectedly, after HCl-doping, the catalyst intrinsic activity of a commercial catalyst increased by a factor of 5. Besides, it was found that while the NH3 surface coverage is little affected by HCl-doping, the chemisorption capacity of NO + O2 undergoes a remarkable promotion that scales with the promotion of the reaction rate. The HCl-effect provided thus an indirect but unambiguous piece of evidence that NO-activation by an O-species is a key rate controlling step of NH3-SCR.

Morphology and crystal facet-dependent activation mechanism of persulfate by V2O5 nanomaterials for organic pollutants degradation

Vanadium pentoxide (V2O5) including nanorod-like V2O5 (VR), nanowire-like V2O5 (VW) and nanospheres (VS) were synthesized by simple hydrothermal methods and then used as heterogeneous catalysts for persulfate activation. A series of characterization containing XRD, XPS, SEM, TEM and BET tests confirmed the different exposed crystal facets, morphologies and specific surface areas for the three kinds of V2O5 catalysts. The experimental results demonstrated that the combination of persulfate with V2O5 was efficient in promoting the degradation of acid orange 7 (AO7). The three types of V2O5 exhibited different abilities to activate persulfate (PS) for AO7 degradation with a sequence of VW > VS > VR, which is probably caused by the larger specific surface area (~30.428 m2 g−1) and the exposed crystal facet (111) with lower Fermi energy and higher positive charge densities for VW. Free radical quenching and ESR studies revealed that both sulfate radical (SO4−) and hydroxyl radical (OH) contributed to AO7 degradation. Furthermore, the prepared catalysts exhibited excellent recyclability and stability.