Oxygen Transfer Reactions Research Articles

MXene-supported Co3Ti and single-atom Co catalyst activated PMS for efficient removal of Pb-EDTA: The involvement of Co (Ⅳ)

Activation of peroxymonosulfate (PMS) by MXene-supported Co3Ti and single-atom Co catalyst (Co@MXene) achieved the efficient decomplexation of lead-ethylenediaminetetraacetic acid (Pb-EDTA) and the recovery of lead (Pb) over the pH range of 3.0–9.0. The removal efficiency of Pb-EDTA reached up to 93.6 % within 30 min and total Pb was completely removed within 15 min. The coordination structure differences between Co3Ti and single-atom Co induced their various electron transfer pathways with PMS, in which Co3Ti brought key effect to the generation of Co (Ⅳ), while single-atom Co and regenerative Co (II) were responsible for the generation of HO and SO4−and 1O2, More importantly, the oxygen transfer reaction from O-Co3Ti to Co3Ti-O and the reducibility of MXene triggered the regeneration of low-valent Co. This study proposed a novel mechanism of Co (Ⅳ) generation and low-valent Co regeneration, which improved the understanding of the electron transfer pathways of Co@MXene/PMS oxidation process.

Thermodynamic analysis on the fate of ash elements in chemical looping combustion of solid fuels – Manganese-Based oxygen carriers

Chemical looping combustion (CLC) is an innovative technology suitable for converting waste-derived fuels into heat and power. The process inherently produces pure CO2, which is highly favorable for carbon capture and storage and could be instrumental for achieving negative emissions. CLC operates by utilizing solid oxygen carriers (OCs) to transfer heat and oxygen between two reactors. The OC play a crucial role in achieving an efficient combustion. Manganese-based OCs are particularly interesting, due to their ability to release gaseous oxygen. However, ash components from solid fuels could alter their oxygen transfer capacity, and cause problems related to corrosion and agglomeration. The objective of this work is to obtain in-depth insights about Mn-based OCs for CLC of waste-derived fuels. This is achieved by investigating phase transitions during CLC of solid fuels when utilizing two manganese-based OCs: manganese oxide and a representative manganese ore. For this purpose, thermodynamic modeling is employed, and a specific focus is given to K, Na, Cu, Zn, and Pb, due to their important role in corrosion and/or agglomeration. Thermodynamic databases are expanded by calculating properties from first-principles. It is shown that Mn-based OCs are suitable for effectively converting waste-derived fuels while limiting corrosion. Furthermore, the iron in manganese ores is found to have positive implications for oxygen-transfer reactions. In terms of alkali release to the gas phase, manganese ore seems to be a more promising material compared to manganese oxide. The pathways for the heavy metals Zn, Cu, and Pb were, meanwhile, independent of the OC type.

Iron(III) and BF3·OEt2-Promoted O-Transfer Reaction of N-Aryl-α,β-Unsaturated Nitrones to Prepare Difluoroboron β-Ketoiminates.

We described an iron(III) and BF3·OEt2-promoted oxygen transfer reaction of N-aryl-α,β-unsaturated nitrones to prepare various N,O-difluoroboron β-ketoiminates in good yields ranging from 24% to 87%. Control experiments revealed that the enaminone was the vital intermediate for the formation of N,O-difluoroboron β-ketoiminates, and iron(III) combined with BF3·OEt2 played as cocatalyst to promote the oxygen transfer reaction through intramolecular cyclization and N-O bond cleavage. More importantly, an estrone-derived N,O-difluoroboron β-ketoiminate was easily prepared in 40% yield from estrone in four steps.

Deoxygenation of Oxiranes by λ3 σ3 -Phosphorus Reagents: A Computational, Mechanistic, and Stereochemical Study.

Invited for this month's cover is Prof. Arturo Espinosa Ferao at the University of Murcia, Spain. The cover picture shows two different ways of reacting a phosphane (R3 P) with the oxirane (epoxide) ring. They arise from phosphorus attacking either the carbon or oxygen ring atoms and promoting carbene or oxygen transfer reactions with eliminations of H2 C=O or CH2 =CH2 , respectively. More information can be found in the Research Article by Arturo Espinosa Ferao .

Untangling the catalytic importance of the Se oxidation state in organoselenium-mediated oxygen-transfer reactions: the conversion of aniline to nitrobenzene.

Seleninic acids and their precursors are well-known oxygen-transfer agents that can catalyze several oxidations with H2O2 as the final oxidant. Until very recently, the Se(iv) "peroxyseleninic" acid species has been considered the only plausible catalytic oxidant. Conversely, in 2020, the involvement of Se(vi) "peroxyselenonic" acid has been proposed for the selenium mediated epoxidation of alkenes. In this work, we theoretically probe different mechanisms of H2O2 activation and of Se(iv) to Se(vi) interconversion. In addition, we investigate through a combined theoretical (DFT) and experimental approach the mechanistic steps leading to the oxidation of aniline to nitrobenzene, when Se(iv) seleninic acid or Se(vi) selenonic acids are used as catalysts and H2O2 as the oxidant. This process encompasses three subsequent organoselenium mediated oxidations by H2O2. These results provide a mechanistic explanation of the advantages and disadvantages of both oxidation states (iv and vi) in the different stages of catalytic oxygen-transfer reactions: hydrogen peroxide activation and actual substrate oxidation. While the Se(vi) "peroxyselenonic" acid is found to be a better oxidant, the privileged role of "peroxyseleninic" acid as the main active species is assessed and its origin is identified in the lower catalyst-distortion that seleninic acid undergoes when activating H2O2. Conversely, the higher catalyst-distortion that characterizes the reaction of selenonic acid with H2O2 supports an inactivating role of Se(iv) to Se(vi) interconversion.

Dynamics of carbene formation in the reaction of methane with the tantalum cation in the gas phase.

The controlled activation of methane has drawn significant attention throughout various disciplines over the last few decades. In gas-phase experiments, the use of model systems with reduced complexity compared to condensed-phase catalytic systems allows us to investigate the intrinsic reactivity of elementary reactions down to the atomic level. Methane is rather inert in chemical reactions, as the weakening or cleavage of a C-H bond is required to make use of methane as C1-building block. The simplest model system for transition-metal-based catalysts is a mono-atomic metal ion. Only a few atomic transition-metal cations activate methane at room temperature. One of the most efficient elements is tantalum, which forms a carbene and releases molecular hydrogen in the reaction with methane: Ta+ + CH4 → TaCH2+ + H2. The reaction takes place at room temperature due to efficient intersystem crossing from the quintet to the triplet surface, i.e., from the electronic ground state of the tantalum cation to the triplet ground state of the tantalum carbene. This multi-state reactivity is often seen for reactions involving transition-metal centres, but leads to their theoretical treatment being a challenge even today. Chemical reactions, or to be precise reactive collisions, are dynamic processes making their description even more of a challenge to experiment and theory alike. Experimental energy- and angle-differential cross sections allow us to probe the rearrangement of atoms during a reactive collision. By interpreting the scattering signatures, we gain insight into the atomistic mechanisms and can move beyond stationary descriptions. Here, we present a study combining collision energy dependent experimentally measured differential cross sections with ab initio calculations of the minimum energy pathway. Product ion velocity distributions were recorded using our crossed-beam velocity map imaging experiment dedicated to studying transition-metal ion molecule reactions. TaCH2+ velocity distributions reveal a significant degree of indirect dynamics. However, the scattering distributions also show signatures of rebound dynamics. We compare the present results to the oxygen transfer reaction between Ta+ and carbon dioxide, which we recently studied.

Regulation of dye-decolorizing peroxidase gene expression in Pleurotus ostreatus grown on glycerol as the carbon source.

Dye-decolorizing peroxidases (DyPs) (E.C. 1.11.1.19) are heme peroxidases that catalyze oxygen transfer reactions similarly to oxygenases. DyPs utilize hydrogen peroxide (H2O2) both as an electron acceptor co-substrate and as an electron donor when oxidized to their respective radicals. The production of both DyPs and lignin-modifying enzymes (LMEs) is regulated by the carbon source, although less readily metabolizable carbon sources do improve LME production. The present study analyzed the effect of glycerol on Pleurotus ostreatus growth, total DyP activity, and the expression of three Pleos-dyp genes (Pleos-dyp1, Pleos-dyp2 and Pleos-dyp4), via real-time RT-qPCR, monitoring the time course of P. ostreatus cultures supplemented with either glycerol or glucose and Acetyl Yellow G (AYG) dye. The results obtained indicate that glycerol negatively affects P. ostreatus growth, giving a biomass production of 5.31 and 5.62 g/L with respective growth rates (micra; m) of 0.027 and 0.023 h-1 for fermentations in the absence and presence of AYG dye. In contrast, respective biomass production levels of 7.09 and 7.20 g/L and growth rates (μ) of 0.033 and 0.047 h-1 were observed in equivalent control fermentations conducted with glucose in the absence and presence of AYG dye. Higher DyP activity levels, 4,043 and 4,902 IU/L, were obtained for fermentations conducted on glycerol, equivalent to 2.6-fold and 3.16-fold higher than the activity observed when glucose is used as the carbon source. The differential regulation of the DyP-encoding genes in P. ostreatus were explored, evaluating the carbon source, the growth phase, and the influence of the dye. The global analysis of the expression patterns throughout the fermentation showed the up- and down- regulation of the three Pleos-dyp genes evaluated. The highest induction observed for the control media was that found for the Pleos-dyp1 gene, which is equivalent to an 11.1-fold increase in relative expression (log2) during the stationary phase of the culture (360 h), and for the glucose/AYG media was Pleos-dyp-4 with 8.28-fold increase after 168 h. In addition, glycerol preferentially induced the Pleos-dyp1 and Pleos-dyp2 genes, leading to respective 11.61 and 4.28-fold increases after 144 h. After 360 and 504 h of culture, 12.86 and 4.02-fold increases were observed in the induction levels presented by Pleos-dyp1 and Pleos-dyp2, respectively, in the presence of AYG. When transcription levels were referred to those found in the control media, adding AYG led to up-regulation of the three dyp genes throughout the fermentation. Contrary to the fermentation with glycerol, where up- and down-regulation was observed. The present study is the first report describing the effect of a less-metabolizable carbon source, such as glycerol, on the differential expression of DyP-encoding genes and their corresponding activity.

Iron(iii)/quinoxaline-derived N,N-ligand catalyzed oxygen transfer reaction of N-vinyl nitrones through selective 4π-electrocyclization and N–O bond cleavage

We describe an iron(iii)/quinoxaline-derived N,N-ligand promoted O-transfer reaction of N-vinyl nitrones through selective O-4π-electrocyclization and N–O bond cleavage to prepare a variety of 2,5-dihydrooxazoles in good yields.

Criegee Intermediate-Mediated Oxidation of Dimethyl Disulfide: Effect of Formic Acid and Its Atmospheric Relevance.

The oxidation-reduction reactions of disulfides are important in both chemistry and biology. Dimethyl disulfide (DMDS), the smallest reduced sulfur species with a disulfide bond, is emitted in significant quantities from natural sources and contributes to the formation of aerosols and hazardous haze. Although atmospheric removal of DMDS via the reactions with OH or NO3 radicals and photolysis is known, the reactions of DMDS with other atmospheric oxidants are yet to be explored. Herein, using quantum chemical calculations, we explored the reactions of DMDS with CH2OO (formaldehyde oxide) and other methyl-substituted Criegee intermediates. The various reaction pathways evaluated were found to have positive energy barriers. However, in the presence of formic acid, a direct oxygen-transfer pathway leading to the corresponding sulfoxide (CH3SS(O)CH3) was found to proceed through a submerged transition state below the separated reactants. Calculations for the methyl-substituted Criegee intermediates, particularly for anti-CH3CHOO, show a significant increase in the rate of the direct oxygen-transfer reaction when catalyzed by formic acid. The presence of formic acid also alters the mechanism and reduces the enthalpic barrier of a second pathway, forming thioformaldehyde and hydroperoxide without any rate enhancement. Our data indicated that, although Criegee intermediates are unlikely to be an important atmospheric sink of DMDS under normal conditions, in regions rich in DMDS and formic acid, the formic acid-catalyzed Criegee intermediate-mediated oxidation of DMDS via the direct oxygen-transfer pathway could lead to organic sulfur compounds contributing to atmospheric aerosol.

Highly selective synthesis of surface FeIV=O with nanoscale zero-valent iron and chlorite for efficient oxygen transfer reactions

High-valent iron-oxo species (FeIV=O) has been a long-sought-after oxygen transfer reagent in biological and catalytic chemistry but suffers from a giant challenge in its gentle and selective synthesis. Herein, we propose a new strategy to synthesize surface FeIV=O (≡FeIV=O) on nanoscale zero-valent iron (nZVI) using chlorite (ClO2-) as the oxidant, which possesses an impressive ≡FeIV=O selectivity of 99%. ≡FeIV=O can be energetically formed from the ferrous (FeII) sites on nZVI through heterolytic Cl-O bond dissociation of ClO2- via a synergistic effect between electron-donating surface ≡FeII and proximal electron-withdrawing H2O, where H2O serves as a hydrogen-bond donor to the terminal O atom of the adsorbed ClO2- thereby prompting the polarization and cleavage of Cl-O bond for the oxidation of ≡FeII toward the final formation of ≡FeIV=O. With methyl phenyl sulfoxide (PMS16O) as the probe molecule, the isotopic labeling experiment manifests an exclusive 18O transfer from Cl18O2- to PMS16O18O mediated by ≡FeIV=18O. We then showcase the versatility of ≡FeIV=O as the oxygen transfer reagent in activating the C-H bond of methane for methanol production and facilitating selective triphenylphosphine oxide synthesis with triphenylphosphine. We believe that this new ≡FeIV=O synthesis strategy possesses great potential to drive oxygen transfer for efficient high-value-added chemical synthesis.

Role of oxygen transfer and surface reaction in catalytic performance of VOx-Ce1–xZrxO2 for propane dehydrogenation

The bulk oxygen transfer and surface reaction as important parts of the chemical looping-related process are crucial for the rational design of new redox catalysts. This paper describes an experimental study on the effect of bulk oxygen transfer and surface reaction in Ce1–xxO2 supported VOx redox catalysts for the chemical looping oxidative propane dehydrogenation reaction. It was found that the introduction of Zr dictates the reaction performance of the redox catalyst by modulating the bulk oxygen transfer and surface reaction. The kinetic study reveals that the instantaneous reduction rate of the redox catalysts is determined by the H-abstraction step in the surface reaction. The introduction of Zr can reduce the activation energy of the H-abstraction step, which leads to the enhancement of the instantaneous reduction rate. Meanwhile, the oxygen supply capacity of the cerium oxide is increased by Zr, allowing the surface reaction to proceed over longer durations. Furthermore, the reaction model derived from the kinetics study is validated using a number of (quasi) in situ techniques. This study provides fundamental insights into the role of bulk oxygen transfer and surface reaction in chemical looping or related process.

Photochemical Oxidation of Dimethyl Sulfide with Triplet Nitro Compounds

The mechanism of oxygen atom transfer between triplet molecules of a nitro compound and dimethyl sulfide is considered. This reaction pathway can be one of the possible routes in the reaction of photochemical oxidation of the sulfur compound. Quantum-chemical modeling has shown the feasibility of such a reaction as having a fairly low activation energy. The transition states of the reaction have almost the same structure in various solvents. The calculation of spin densities and charges on atoms in transition states hasshown no significant charge separation. This finding is also confirmed by calculation of the activation parameters of the oxygen transfer reaction involving various solvents. The activation energies remain almost unchanged with an increase in the solvent permittivity. All the data obtained suggest the radical mechanism of oxygen atom transfer with the participation of the triplet nitro compound.

Elucidation of Molecular‐level Mechanisms of Oxygen Atom Reactions with Chlorine Ion in NaCl Solutions using Molecular Dynamics Simulations Combined with Density Functional Theory

AbstractMolecular dynamics simulations combined with density functional theory were performed to investigate the reaction mechanisms for oxygen atom and chlorine ion in NaCl solutions. Considering the ground and first excited states of the oxygen atom, four bulk systems, O(3P)‐NaCl‐63H2O, O(1D)‐NaCl‐63H2O, O(3P)‐4NaCl‐63H2O, and O(1D)‐4NaCl‐63H2O were studied. The main reaction pathway depended on the concentration of the aqueous electrolyte solution. For a dilute solution with a 1 : 64 ratio of NaCl to H2O, the singlet oxygen atom first attached a water molecule to produce a neutral OH radical, and then the OH radical and chlorine ion approach each other to form an intermediate structure [Cl…OH]−. Synchronously, the intermediate transferred charge to the solvated OH radical by accessing the hydrogen bond network. Finally, neutral HOCl and OH− ions were formed. For a dense solution with a 4 : 64 ratio of NaCl to H2O, a singlet oxygen atom was directly combined with Cl− to produce ClO− via an oxygen transfer reaction. The subsequent ab‐initio energy computations indicated the most probable mechanism, where the O atom directly combines with Cl− ion to OCl−. This study provides insights into the fundamental mechanisms of the behavior of dissolved oxygen radicals in aqueous electrolyte solutions.

Bacteria and Virus Inactivation: Relative Efficacy and Mechanisms of Peroxyacids and Chlor(am)ine.

Peroxyacids (POAs) are a promising alternative to chlorine for reducing the formation of disinfection byproducts. However, their capacity for microbial inactivation and mechanisms of action require further investigation. We evaluated the efficacy of three POAs (performic acid (PFA), peracetic acid (PAA), and perpropionic acid (PPA)) and chlor(am)ine for inactivation of four representative microorganisms (Escherichia coli (Gram-negative bacteria), Staphylococcus epidermidis (Gram-positive bacteria), MS2 bacteriophage (nonenveloped virus), and Φ6 (enveloped virus)) and for reaction rates with biomolecules (amino acids and nucleotides). Bacterial inactivation efficacy (in anaerobic membrane bioreactor (AnMBR) effluent) followed the order of PFA > chlorine > PAA ≈ PPA. Fluorescence microscopic analysis indicated that free chlorine induced surface damage and cell lysis rapidly, whereas POAs led to intracellular oxidative stress through penetrating the intact cell membrane. However, POAs (50 μM) were less effective than chlorine at inactivating viruses, achieving only ∼1-log PFU removal for MS2 and Φ6 after 30 min of reaction in phosphate buffer without genome damage. Results suggest that POAs' unique interaction with bacteria and ineffective viral inactivation could be attributed to their selectivity toward cysteine and methionine through oxygen-transfer reactions and limited reactivity for other biomolecules. These mechanistic insights could inform the application of POAs in water and wastewater treatment.

Isotopically labeled ozone: A new approach to elucidate the formation of ozonation products

As ozonation becomes a widespread treatment for removal of chemicals of emerging concern from wastewater treatment plant effluents, there are increasing concerns regarding the formation of ozonation products (OPs), and their possible impacts on the aquatic environment and eventually human health. In this study, a novel method was developed that utilizes heavy oxygen (18O2) for the production of heavy ozone ([18O1]O2, [18O2]O1, [18O3]) to actively label OPs from oxygen transfer reactions. To establish and validate this new approach, venlafaxine with a well-described oxygen transfer reaction (tertiary amine -> N-oxide) was chosen as a model compound. Observed 18O/16O ratios in the major OP venlafaxine N-oxide (NOV) correlated with expected 18O purities based on tracer experiments. These results confirmed the successful labeling with heavy oxygen and furthermore demonstrate the potential to monitor NOV as an indicator of 18O/16O ratios during ozonation. As a next step, 18O/16O ratios were used to elucidate the formation mechanism of previously described OPs from sulfamethoxazole (SMX). Seven OPs were detected including the frequently described nitro-SMX, which was formed with a maximum yield of 3.2% (of initial SMX). With the successful labeling of six of the seven OPs from sulfamethoxazole, it was possible to confirm their previously proposed formation pathways, and to distinguish oxygen transfer from electron transfer reactions. 18O/16O ratios in OPs indicate that hydroxylation of the aromatic ring and formation of nitro-groups mostly follows oxygen transfer reactions, while electron transfer reactions initiate the formation of hydroxylamine and the abstraction of NH2 leading to catechol.

Oxygen transfer reaction of haloalkyl amides catalyzed by phenylboronic acid

Nitrile derivatives are important building blocks in organic synthesis. Herein, we report the serendipitous discovery of an oxygen transfer reaction that produces hydroxyalkyl nitriles from the sequential dehydration and hydrolysis of haloalkyl amides. Product yields of up to 91% were achieved, and the phenylboronic acid was recovered as triphenylboroxine. The triphenylboroxine was reused as a catalyst without any loss of catalytic activity. A probable catalytic pathway was proposed based on control experiments and DFT calculations.

An economic, self-supporting, robust and durable LiFe5O8 anode for sulfamethoxazole degradation

Electrochemically activating peroxydisulfate (PDS) to degrade organic pollutants is one of the most attractive advanced oxidation processes (AOPs) to address environmental issues, but the high cost, poor stability, and low degradation efficiency of the anode materials hinder their application. Herein, an economic, self-supporting, robust, and durable LiFe5O8 on Fe substrate (Fe@LFO) anode is reported to degrade sulfamethoxazole (SMX). When PDS is electrochemically activated by the Fe@LFO anode, the degradation rate of SMX is significantly improved. It is found that hydroxyl radicals (•OH), superoxide radical (O2•–), singlet oxygen (1O2), Fe(Ⅳ), activated PDS (PDS*), and direct electron transfer (DET) reactions synergistically contribute to the degradation of SMX, which can realize the degradation of SMX in four possible routes: cleavage of the isoxazole ring, hydroxylation of the benzene ring, oxidation of the aniline group, and cleavage of the S–N bond, as evidenced by a series of tests of radicals quenching, electron paramagnetic resonance (EPR), linear sweep voltammetry (LSV) and liquid chromatograph mass spectrometer (LC-MS). Furthermore, Fe@LFO has good structural stability, excellent cyclability and low degradation cost, demonstrating its great potential for practical applications. This work contributes to a stable and effective anode material in the field of AOPs.

Oxygen transfer reactivity mediated by nickel perfluoroalkyl complexes using molecular oxygen as a terminal oxidant.

Nickel perfluoroethyl and perfluoropropyl complexes supported by naphthyridine-type ligands show drastically different aerobic reactivity from their trifluoromethyl analogs resulting in facile oxygen transfer to perfluoroalkyl groups or oxygenation of external organic substrates (phosphines, sulfides, alkenes and alcohols) using O2 or air as a terminal oxidant. Such mild aerobic oxygenation occurs through the formation of spectroscopically detected transient high-valent NiIII and structurally characterized mixed-valent NiII-NiIV intermediates and radical intermediates, resembling O2 activation reported for some Pd dialkyl complexes. This reactivity is in contrast with the aerobic oxidation of naphthyridine-based Ni(CF3)2 complexes resulting in the formation of a stable NiIII product, which is attributed to the effect of greater steric congestion imposed by longer perfluoroalkyl chains.

Photoelectrochemical oxidation of methyl phenyl sulfide with oxygen atom transfer way on Mo-BiVO4 photoanode

Photoelectrochemical oxidation of methyl phenyl sulfide with water as the only oxygen source on Mo-BiVO 4 photoanode. Mo-BiVO 4 photoelectrode performs oxygen transfer reaction in PEC oxidation of MPS. • Mo-BiVO 4 photoelectrode was applied to oxidation of methyl phenyl sulfide. • PEC oxygen atom transfer (OAT) reaction was achieved on Mo-BiVO 4 photoelectrode. • Isotopic labelling experiment with H 2 18 O revealed oxygen atoms in MPSO were mainly from water. Photoelectrochemical (PEC) selective oxidation is an environment-friendly strategy to obtain value-added chemicals. Herein, we report the PEC oxidation of methyl phenyl sulfide (MPS) into methyl phenyl sulfoxide (MPSO) with 85.7% selectivity and 36.2% conversion on molybdenum doped bismuth vanadate (Mo-BiVO 4 ) photoelectrode under simulated sunlight illumination (AM 1.5 G, 100 mW cm -2 ). Isotopic labelling experiment with H 2 18 O was conducted to clearly reveal that the oxygen atoms in the MPSO were mainly from water. Based on these results, the application of Mo-BiVO 4 has been extended to PEC selective oxidation.

Anomalous durability of (001) plane against oxygen vacancy injection at electrode/rutile-TiO[formula omitted] interfaces

We have investigated the electro-coloration of a rutile TiO2 single crystal by the voltage-bias annealing in dry air between a point cathode and a flat anode. The electro-coloration is due to the conductive VO filament that grows from the cathode/TiO2 interface to mm size. We proposed that the growth mechanism of this macroscopic size VO filament is the oxygen (O2−) transfer reaction at the anode interface followed by the thermally assisted-electric field-induced VO diffusion to the cathode. It was found that no electro-coloration occurs on (001), whereas it occurs on (110) and (100). This striking contrast between the surface crystal orientations was found to be due to the anisotropic VO diffusion that was found to be much faster perpendicular to [001] than parallel. Accordingly, VO is not injected into the anode/(001) interface in the oxygen transfer reaction. The proposed mechanism was examined by the surface-sensitive TOF-SIMS and the bulk-sensitive dynamic SIMS for analyzing the VO spatial distribution using the 18O isotope tracer. The anomalous durability of the (001) plane against the VO injection suggests that the atomic arrangement of TiO2 at the electrode interface is crucial for controlling the VO filament growth in resistive switching devices.