Dissociation Of Molecular Oxygen Research Articles

Synergistic enhancement of singlet oxygen generation in Au and oxygen vacancy co-modified Bi2MoO6 ultrathin nanosheets for efficient ciprofloxacin degradation

Solar-driven molecular oxygen activation (MOA) is crucial for generating reactive oxygen species (ROS) for pollutant degradation, while the low activation efficiency greatly weakens the degradation efficiency. Herein, oxygen vacancies (OVs) and Au nanoparticles are co-introduced into Bi2MoO6 (ABMOH) to enhance the photocatalytic activity of Bi2MoO6 (BMO), thereby promoting MOA efficiency. Density functional theory demonstrates that the introduction of OVs not only improves the molecular oxygen adsorption on BMO, and but also strengthens the O-O bond dissociation of molecular oxygen, which is beneficial to MOA. Meanwhile, the unique localized surface plasmon resonance effect of Au nanoparticles immensely increases the photo-absorption capacity. Crucially, both OVs and Au nanoparticles work as “electron traps” to capture photogenerated electrons, thereby accelerating charge transfer. Based on the advantage of OVs and Au nanoparticles, ABMOH displays excellent MOA efficiency, and the degradation rate constant of ciprofloxacin (CIPF) by ABMOH-4 is 3.62-fold higher than BMO. Free radical trapping experiment and electron spin resonance suggest that singlet oxygen (1O2) can be selectively formed in the ABMOH system for CIPF degradation, and superoxide radical (•O2–) conversion and energy transfer are two pathways for 1O2 formation. This investigation serves as a beacon for the strategic design of high-performance and stable photocatalysts for MOA activation, paving the way for advancements in environmental remediation.

Ultrafast UV Luminescence of ZnO Films: Sub‐30 ps Decay Time with Suppressed Visible Component

AbstractUltrafast sub‐100 picosecond luminescence is vital in many applications involving ultrafast events and time‐of‐flight systems. Materials exhibiting fast luminescence, such as barium fluoride (BaF2) and zinc oxide (ZnO), also suffer from an intrinsically slow nanosecond (ns) to microsecond (µs) luminescence. Here, 2.2 micrometer (µm)‐ to 5.7 µm‐thick undoped ZnO films on soda‐lime glass (SLG) substrates without a buffer layer by a hybrid pulsed reactive magnetron sputtering operating in the medium‐frequency range (MF magnetron) assisted by an electron cyclotron wave resonance (ECWR) plasma is deposited. The undoped ZnO films exhibited superior optical properties characterized by intense ultraviolet (UV) luminescence, unprecedented ultrafast decay times, and for the case of MF+ECWR‐deposited films, suppressed defect‐related visible luminescence. The 2.2 µm‐thick MF‐deposited film exhibited the fastest 9‐ps decay time at room temperature. The impressive properties of the films are attributed to the use of advanced deposition technology with properly tuned plasma parameters, especially a high degree of dissociation of molecular oxygen together with an increased proportion of activated zinc particles, leading to a higher deposition rate, better crystallinity, fewer defects, and a lower proportion of oxygen vacancies. These films will pave the way toward the development of time‐of‐flight detectors, high‐resolution nuclear imaging cameras, and high‐rate ultrafast timing devices.

Absolute calibration of the ratio of Xe/O two-photon absorption cross-sections for O-TALIF applications

The paper presents a calibration of the ratio of two-photon absorption cross-sections, σXe(2)/σO(2) , necessary for the absolute O-atom density measurements by two-photon absorption laser-induced fluorescence (TALIF) technique. To calibrate the ratio of the cross-sections, a special discharge with 100% dissociation of molecular oxygen, and so with a known ‘reference’ density of O-atom [O] ref=2⋅ [O2] was suggested. This is a nanosecond capillary discharge in N2:O2 mixtures with a few percent of oxygen at a reduced electric field of a few hundred of Townsend and specific deposited energy of about 1 eV mol−1. Voltage at the electrodes, electrical current in the plasma, longitudinal electric field and energy delivered to the gas were measured with 0.2 ns synchronisation. Additionally, radial distribution of emission of excited nitrogen molecules and gas temperature in the discharge and afterglow were obtained experimentally. Detailed 1D kinetic modeling was suggested to confirm complete O2 dissociation and to analyse the main reactions. By comparing the data measured by TALIF technique with the ‘reference’ density of oxygen atoms [O] ref , the ratio of the two-photon absorption cross-sections σXe(2)/σO(2) was determined.

Adsorbed oxygen atoms for improving the oxidative dehydrogenation of ethane over B-site-doped layered perovskite La2Ti2O7

In this study, Nd, Ga, and Sm were used to partially replace Ti in layered perovskite La2Ti2O7 (A2B2O7 type) with the aim of developing a highly efficient low-temperature catalyst for the oxidative dehydrogenation of ethane (ODHE). Ethylene was successfully produced by the ODHE over the modified catalysts at temperatures of as low as 600 °C, and the Ga-doped catalyst exhibited the highest ethylene yield of 16.9 % at 625 °C with a high gas hourly space velocity of 35,273 h−1 and short reactant–catalyst contact time of 0.1 s. Thermal activation improved the ethylene yield to 33.6–39.4 % at 650–700 °C with a short contact time (<0.1 s) and productivity of approximately 10 gethylene·gcatalyst−1·h−1, which exceeds reported values. However, the pure catalytic activity could not be depicted at higher temperatures (>700 °C) because the reaction became more complex owing to thermally activated processes such as thermal dehydrogenation, thermal–oxidative dehydrogenation, and reforming reactions. The effects of B-site doping were explored through in situ characterization and density functional theory calculations, and a mechanism for the ODHE was proposed based on the results. Adsorbed oxygen atoms, which form by the dissociation of molecular oxygen at high temperatures, are responsible for the selective dehydrogenation of ethane to ethylene. Overall, the electronic modification of the B-site doped La2Ti2O7 catalysts improved the catalytic activity at 525–575 °C, and the experimental and calculation results confirmed that dissociatively adsorbed oxygen atoms were responsible for the improved ODHE.

New insight into dissociation of molecular oxygen at temperatures below 5000 K

The data available in the literature on measurements of the rate coefficient of molecular oxygen dissociation were considered and structured. Modern models of hydrocarbons combustion were analyzed considering values of the O2 dissociation rate constant. Precision measurements of the rate of O2 dissociation behind shock waves at temperatures of 2500–5000 ± 50 K and pressures of 1.2–2.5 bar were carried out using atomic resonance absorption spectrometry on O atom (O-ARAS). The ARAS measurements of the absolute concentration of oxygen atoms were calibrated in the conditions of complete dissociation of N2O and O2, considering the temperature splitting of the calibration curves. Using kinetic modeling, a detailed analysis of experimental uncertainties was carried out with an assessment of the influence of impurities of various origin at the dissociation of O2. An updated expression for the rate constant of the reaction O2 + Ar = 2O + Ar was obtained in the form kdiss(±15%)=1.30·1014·exp(−108.95[kcalmol]/RT) cm3 mol−1 s−1. A significant influence of the O2 dissociation rate constant on the predictive ability of modern models of hydrocarbons (on the example of biofuels) combustion at high temperatures was shown. Recommendations were formulated on the use of the corresponding oxygen dissociation rate constant in the development and/or refinement of combustion kinetic models.

A platinum ensemble catalyst for room-temperature removal of formaldehyde in the air

Minimal use of noble metals is ideal in developing catalytic systems against carcinogenic formaldehyde (FA) in air. Although single-atom catalysts (SACs) have been proposed to maximize atomic utilization, metals dispersed to the single-atom limit are less durable in redox environments. A highly dispersed platinum (Pt) ensemble (Ptn) on titanium dioxide (TiO2) was synthesized and validated to achieve 100% conversion of 100 ppm FA in dry air at room temperature (RT) at a gas hourly space velocity of 47,771 h−1. In contrast, Pt SAC (Pt1/TiO2) and a reference Pt nanoparticle catalyst (PtNP/TiO2) exhibited much lower performances. The turnover frequencies (TOFs) of Ptn/TiO2, Pt1/TiO2, and PtNP/TiO2 for the RT FA oxidation reaction were 0.03, 0.01, and 0.005 s−1, respectively. The critical role of the surface lattice oxygen (Olatt) in the overall reaction was supported by the prominence of the Mars van Krevelen kinetics in FA oxidation by the Ptn catalyst. The performance of the PtNP catalyst matched with Ptn only when the Pt loading in the former was raised to 2 wt%. Hence, the Pt dose can be reduced by one-fourth through the ensemble form dispersed at the sub-nanometer scale. The density functional theory simulation also distinguished the roles of different Pt catalysts. The Ptn sites could serve as an oxygen reservoir (effective dissociation of molecular oxygen) to promote proximate reactions (between the adsorbed –CHO and surface Olatt species). Conversely, Pt1 is a single site that restricts proximate reactions with vulnerability to surface poisoning.

REFINED DATA ON O2 DISSOCIATION RATE MEASURED BYO-ARAS BEHIND SHOCKWAVES

The formation of atomic oxygen in high-temperature gas flows affects both the thermodynamic state of the gas and the kinetics of proceeding chemical processes. During hypersonic and space flights, there is still a significant lack of understanding of the phenomena of flow around high-speed vehicles. One of the main reactions occurring in the bow shock zone is the dissociation of molecular oxygen into O atoms. Experimental studies of the kinetics of O2 dissociation were carried out by various methods; however, the O2 dissociation rate constants in modern combustion mechanisms still differ by orders of magnitude. Therefore, the clarification of these values is a very urgent task. In this work, precision measurements of the rate constant of oxygen dissociation performed by the ARAS (atomic resonance absorption spectroscopy) method in the temperature range of 2600-5000 K behind the reflected shock waves were carried out which made it possible to noticeably refine the previous data. The best fit to the present experimental data is given by the expression k = 1.34 ± 0.4 • 1014 exp(-(53620 ± 2620)/T) cm6 /(mole-s).

Investigating the electrochemical performance of Nd1-xSrxCo0.8Fe0.2O3−δ (0 ≤ x ≤ 0.85) as cathodes for intermediate temperature solid oxide fuel cells

Perovskite-type structure oxides with the nominal chemical composition Nd1-xSrxCo0.8Fe0.2O3−δ (0 ≤ x ≤ 0.85) (NSCF) were synthesized by solid-state method to investigate the effect of Sr-doping on the crystal structure and electrochemical performance in the intermediate temperature range of 600 °C–750 °C. The electrical conductivity of the sintered NSCF pellets was found to be in the range of 300–1000 S cm−1. All the NSCF compositions showed a transition from semiconducting to metallic behavior with an increase in temperature. NSCF showed reactivity with the La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM) electrolyte. The electrochemical performance was tested by preparing the symmetrical cells with the configuration 70 wt% NSCF +30 wt% LSGM using LSGM electrolyte in the temperature range of 650–800 °C. AC-impedance results showed a decrease in polarization resistance (Rp) of the cathode with increase in Sr-doping due to increase in electrical conductivity. Among the samples studied, composite electrode of Nd0.3Sr0.7Co0.8Fe0.2O3−δ – LSGM showed the lowest area specific resistance (ASR) of 0.1 Ω cm2 at 750 °C in air. It was chosen to investigate the effect of pO2 on the electrochemical performance of the cathode to determine the rate determining step (RDS) in oxygen reduction reaction (ORR). Dissociation of molecular oxygen into oxygen atoms seems to be the RDS in the ORR.

Catalyzed oxidation of nuclear graphite by simulated fission products Sr, Eu, and I

The influence of three fission products Sr, Eu, and I on the oxidation of IG-110 nuclear graphite was studied in the temperature range of 400 to 1000 °C. Sr and Eu were introduced as chlorides, and I was introduced as NaI. The temperature dependence of both CO2 and CO production during the graphite oxidation measured with mass spectroscopy and infrared spectrometry shows that the introduction of these three compounds to graphite significantly decreases the onset temperature for the oxidation of graphite. Among the three compounds, NaI is the most active towards the oxidation reaction, characterized by a significant decrease of the onset temperature from approximately 650 to 400 °C before and after its introduction to graphite. Separate measurements of CO2 and CO concentration at varying temperatures enable the calculation of the activation energy for the formation of CO2 and CO. The activation energies for the oxidation of pure and fission product-impregnated graphite samples decrease in the following order: standard IG-110 graphite, EuCl3-impregnated IG-110, SrCl2-impregnated IG-110, and NaI-impregnated IG-110. This trend indicates that the three compounds catalyze the oxidation of graphite at temperatures relevant to the operation of high-temperature gas-cooled reactors. Furthermore, it is found that the three compounds can also affect the molar ratio of reaction products CO2 and CO, and the rates of the graphite oxidation. At temperatures higher than about 850 °C, the impregnated samples exhibit lower CO2: CO ratios than the pure graphite. Different from EuCl3 and NaI, the introduction of SrCl2 decreases the graphite oxidation rates at temperatures higher than about 770 °C. Their catalytic mechanism can be understood based on a redox cycle of the intermediate active species, promoting the dissociation of molecular oxygen and transfer to the carbon.

Probing borophene oxidation at the atomic scale

Two-dimensional boron (i.e. borophene) holds promise for a variety of emerging nanoelectronic and quantum technologies. Since borophene is synthesized under ultrahigh vacuum (UHV) conditions, it is critical that the chemical stability and structural integrity of borophene in oxidizing environments are understood for practical borophene-based applications. In this work, we assess the mechanism of borophene oxidation upon controlled exposure to air and molecular oxygen in UHV via scanning tunneling microscopy andspectroscopy, x-ray photoelectron spectroscopy, and density functional theory calculations. While borophene catastrophically degrades almost instantaneously upon exposure to air, borophene undergoes considerably more controlled oxidation when exposed to molecular oxygen in UHV. In particular, UHV molecular oxygen dosing results in single-atom covalent modification of the borophene basal plane in addition to disordered borophene edge oxidation that shows altered electronic characteristics. By comparing these experimental observations with density functional theory calculations, further atomistic insight is gained including pathways for molecular oxygen dissociation, surface diffusion, and chemisorption to borophene. Overall, this study provides an atomic-scale perspective of borophene oxidation that will inform ongoing efforts to passivate and utilize borophene in ambient conditions.

Oxygen and Chlorine Dual Vacancies Enable Photocatalytic O2 Dissociation into Monatomic Reactive Oxygen on BiOCl for Refractory Aromatic Pollutant Removal.

Room-temperature molecular oxygen (O2) dissociation is challenging toward chemical reactions due to its triplet ground-state and spin-forbidden characteristic. Herein, we demonstrate that BiOCl of oxygen and chlorine dual vacancies can photocatalytically dissociate O2 into monatomic reactive oxygen (•O-) for the ring opening of aromatic refractory pollutants toward deep oxidation. The electron-rich and geometry-flexible dual vacancies of oxygen and chlorine remarkably lengthen the O-O bond of adsorbed O2 from 1.21 to 2.74 Å, resulting in the rapid O2 dissociation and the subsequent •O- formation. During the photocatalytic degradation of sulfamethazine, the in situ-formed •O- plays an indispensable role in breaking the critical intermediate of pyrimidine containing a stubborn aromatic heterocyclic ring, thus facilitating the overall mineralization. More importantly, BiOCl of oxygen and chlorine dual vacancies is also superior to its monovacancy counterparts on the degradation of other refractory pollutants containing conjugated six-membered rings, including p-chlorophenol, p-chloronitrobenzene, p-hydroxybenzoic acid, and p-nitrobenzoic acid. This study sheds light on the importance of sophisticated defects for regulating the O2 activation manner and deliveries a novel O2 activation approach for environmental remediation with solar energy.

Sensitivity Analysis of Thermochemical Kinetics Modeling for Hypersonic Air Flows

A computational analysis is used to model Mach 5 and Mach 7 flows over a cylinder, where freestream properties are representative of experiments to be conducted in the Hypervelocity Expansion Tube at the California Institute of Technology. A sensitivity analysis is conducted using the polynomial chaos expansion method, and Sobol indices are used to determine which thermochemical nonequilibrium phenomena most affect various quantities of interest. The results show that the dissociation of molecular oxygen through interaction with molecular nitrogen and with atomic oxygen reactions dominates the determination of surface pressure, surface heat transfer, drag, heating rate, and rotational temperature, whereas the first two Zeldovich reactions dominate the surface number density of NO. The reaction is found to be less important than other reactions. Surface pressure and drag are also shown to be relatively insensitive overall. The results also indicate flow separation and recirculation near the trailing edge of the cylinder. These findings may help diagnostic developments to lower discrepancies between computation and experiments, and indicate that the Hypervelocity Expansion Tube experiments should be successful for the future evaluation of thermochemistry modeling.

ВЛИЯНИЕ ФИЗИЧЕСКИХ ПРОЦЕССОВ В ПРЕДПЛАМЕННОЙ ОБЛАСТИ НА ГОРЕНИЕ ЧАСТИЦ АЛЮМИНИЯ В КИСЛОРОДСОДЕРЖАЩИХ СРЕДАХ

The processes in preflame region while combustion of aluminum particles in media «79% Ar + 21% O2» и «79% Не + 21% O2» were analyzed. The necessity of oxygen dissociation taking into account for explanation of effect of physical processes on particles rate of combustion is proved. The calculations are implemented for particles of diameter 220 m and ambient pres-sure p=0,1 MPa provided that quasistationarity and symmetry of processes. Values of concentration of dissociating oxidizer on the flame boundary are established to be lower than those calculated without dissociation taking into account (in 2,5 times lower for combustion in helium and by 30% lower for combustion in argon). Distributions of medium temperature and concentrations of oxidizing components are obtained depending on relation of coordinates R of inner points of region to current particle radius R0. The preflame region is revealed to be in the range of 2,4R/R05,1 for burning in helium and to be in the range of 15R/R06,9 for burning in argon. The results of analysis show necessity of molecular oxygen dissociation taking into account in the region under consideration. The results explain differencies of burning rates obtained in experiments from calculated values. Also re-sults of this work explain particles combustion rates ratio in media posessing essentially different transport coefficients.

A novel high-entropy cathode with the A2BO4-type structure for solid oxide fuel cells

For the first time, A2BO4 type high-entropy oxide is applied to SOFC cathode. In this paper, a (La0.2Pr0.2Nd0.2Sm0.2Gd0.2)2CuO4 high-entropy oxide (HE-LCO) is synthesized. The phase structure, DC conductivity, high-temperature thermal expansion and electrochemical performance of HE-LCO are studied in detail. HE-LCO crystallizes in tetragonal symmetry with space group I4/mmm. The thermal expansion coefficient of HE-LCO is 12.19 × 10−6 K−1 in the range of 100–800 °C, which is compatible with GDC electrolyte. The area-specific resistance (ASR) of HE-LCO cathode is 0.52 Ω cm2, and the peak power density of the anode support fuel cell attains 528 mW cm−2 at 700 °C. In addition, the dissociation of molecular oxygen on HE-LCO cathode is recognized to be the rate-limiting step of the ORR kinetics.

Impact of oxygen adsorption on the electronic properties and contact type of a defective epitaxial graphene-SiC interface

Adsorption and dissociation of molecular oxygen on a defective graphene buffer layer (BL) grown on Si-terminated SiC(0001) are herein studied by means of periodic DFT calculations coupled with the nudged elastic band method. We considered a single vacancy (SV) and a divacancy (DV) defective BL on SiC, with or without the uppermost epitaxial monolayer graphene (EG). The adsorption energy of O2 on SV and DV surfaces, producing SV-O and DV-O oxidized systems, is between 2 and 3 times as strong as that on a defect-free BL surface and lacks an energy barrier. In addition, we demonstrate that the n-doping measured in the EG layer of SiC-BL-EG systems, which stems from the charge transfer in the SiC-BL interface, can be fully compensated by oxidizing the DV defective BL. The DV-O-EG interface forms a p-type Schottky contact with a small Schottky barrier height. Instead, a p-type Ohmic contact was measured at the SV-O-EG interface.

H2O and O2 co-adsorption on 3C-SiC (111) by first-principle calculations: The role of water in initial oxidation

First-principle calculations were employed to investigate the initial oxidation behaviors of CVD-SiC in wet oxygen. The H2O/O2 co-adsorption behaviors with different H2O/O2 molecular ratios and coverages on (3 × 3) 3C-SiC (111) surface were studied by geometry optimization and property calculation. The results showed that the OO bond in SiOO structure had higher bond energy than that in Si-O-O-H structure, indicating the weaker bond energy of OO bond in the formed hydroperoxyl. First-principle molecular dynamic (FPMD) simulations confirmed that the formation of hydroperoxyl as an intermediate was feasible during the dissociation of molecular oxygen, which played an important role in O2 activation. The static calculation results indicated that the formation of hydroperoxyl needed to experience a lower activation energy barrier (0.35 eV), which demonstrated more likely occurrence than the direct dissociation of molecular oxygen. In brief, the introduction of molecular water could enhance the oxidation rate of 3C-SiC in initial stage by the formation of hydroperoxyl. This work revealed the initial oxidation mechanism of 3C-SiC (111) in wet oxygen and the role of water in initial oxidation, which could also provide a new view to explain the accelerated oxidation rate of SiC in wet oxygen.

Solar Extreme and Far Ultraviolet Radiation Modeling for Aeronomic Calculations

Modeling the upper atmosphere and ionospheres on the basis of a mathematical description of physical processes requires knowledge of ultraviolet radiation fluxes from the Sun as an integral part of the model. Aeronomic models of variations in the radiation flux in the region of extreme (EUV) and far (FUV) radiation, based mainly on the data of the last TIMED mission measurements of the solar spectrum, are proposed. The EUVT model describes variations in the 5–105 nm spectral region, which are responsible for the ionization of the main components of the earth’s atmosphere. The FUVT model describes the flux changes in the 115–242 nm region, which determines heating of the upper atmosphere and the dissociation of molecular oxygen. Both models use the intensity of the hydrogen Lyman-alpha line as an input parameter, which can currently be considered as one of the main indices of solar activity and can be measured with relatively simpler photometers. A comparison of the results of model calculations with observations shows that the model error does not exceed 1–2% for the FUVT model, and 5.5% for EUVT, which is sufficient for calculating the parameters of the ionosphere and thermosphere.

Molecular oxygen dissociation on tin carbide monolayers with gold adatoms

In this work, the interactions between oxygen molecule O2 with pristine and gold-decorated tin carbide (SnC) monolayers were investigated by using density functional calculations. The results indicate that O2 is adsorbed, with an energy of 0.95 eV, on the pristine SnC nanosheet in a bond-like configuration with each oxygen close to a carbon and a tin atom, respectively. There is a large electronic charge transfer from the SnC monolayer to the O2 molecule, which enlarges the molecule internal bond, indicating an activation towards a peroxo-like state. Also, a gold adatom can strongly bind to the SnC monolayer over a C atom. Furthermore, when O2 interacts with this Au adatom, it is spontaneously dissociated with an energy gain of 1.84 eV and where the final adsorption configuration consists of each oxygen on the top of different tin atoms but sharing the gold one.

Investigation of O2-X (X = Pyrrole or Pyridine) Cluster Photodissociation Near 226 nm.

We have recorded the O-atom velocity map photofragment ion images resulting from the photodissociation of O2-pyrrole and O2-pyridine clusters near 226 nm. To record the images, the O-atom photoproduct was state-selectively ionized and projected onto a two-dimensional (2D) position-sensitive detector. The resulting ion images from the clusters show evidence for three dissociation pathways. In the images from either cluster, we observe an isotropic process with kinetic energy near the one-photon limit, which is due to dissociation of the cluster into molecular subunits followed by secondary dissociation of molecular oxygen. Both O2-pyrrole and O2-pyridine also show a low kinetic energy process that appears to be isotropic in nature. This low kinetic energy process likely results from dissociation of the cluster resulting in significant internal energy in the organic fragment followed by secondary dissociation of O2. Finally, our ion images for O2-pyrrole show O atoms resulting from a two-photon dissociation channel, which has been previously attributed to the formation and subsequent photodissociation of excited O2 (a 1Δg). At similar laser intensities, O2-pyridine does not show significant dissociation through the channel producing O2 (a 1Δg); however, this channel shows a laser intensity dependence for O2-pyridine.

Real-space observation of far- and near-field-induced photolysis of molecular oxygen on an Ag(110) surface by visible light.

Dissociation of molecular oxygen is an important elementary process in heterogeneous catalysis. Here, we report on a real-space observation of oxygen photolysis on the Ag(110) surface at 78 K by far- and near-field excitation in the ultraviolet-near-infrared range using a low-temperature scanning tunneling microscope (STM) combined with wavelength-tunable laser excitation. The photolysis of isolated oxygen molecules on the surface occurs even by visible light with the cross section of ∼10-19 cm2. Time-dependent density functional theory calculations reveal optical absorption of the hybridized O2-Ag(110) complex in the visible and the near-infrared range which is associated with the oxygen photolysis. We suggest that the photolysis mechanism involves a direct charge transfer process. We also demonstrate that the photolysis can be largely enhanced in plasmonic STM junctions, and the cross section is estimated to be ∼10-17 cm-2 in the visible and the near-infrared range, which appears to be an interesting feature of plasmon-induced reactions from the perspective of photochemical conversion with the aid of solar energy.