Postphotoionization has been demonstrated to be an effective method to increase the ionization efficiency of laser desorption ionization. In order to scan samples with compact and hard characteristics from the front side, an ambient pressure laser desorption ionization in combination with a compact postphotoionization assembly (AP-LDI/PI) in reflection mode was developed. The effects of parameters, including laser energy, frequency, and stepper motor velocity, were carefully investigated. The slices of mouse cerebellum were scanned by AP-LDI/PI mass spectrometry in both positive and negative ion modes with a spatial resolution of 10 μm. In addition, the longitudinal sections of Ginkgo biloba were well imaged using AP-LDI/PI with a spatial resolution of 15 μm. The spatial distributions of metabolites, including ginkgo acids, choline, glutamate, and ethoxycoumarin, within the longitudinal sections of Ginkgo biloba were distinctly delineated.

Selective oxidative coupling of methane is fundamentally constrained by the lack of controllable oxygen species for C-H bond activation. Here, we show that electrochemical spillover oxygen species on the Au anode surface in solid oxide electrolysis cells could effectively dictate the CH4 activation pathways. In situ spectroscopy combined with theoretical analysis reveals that anodic polarization produces two oxygen species with distinct reactivity. Under anodic polarization, CH4 activation proceeds predominantly via a methyl radical-mediated pathway, as directly evidenced by synchrotronic photoionization mass spectrometry, thereby enabling selective gaseous C-C coupling. This study deepens the understanding of the nature of electrochemical spillover oxygen while establishing a mechanistic framework for electrochemical modulation of oxygen states to steer selective CH4 oxidation.

In situ synchrotron radiation photoionization mass spectrometry (SR-PIMS) is a powerful tool for detecting gas-phase species including intermediates and products in gas-solid catalytic reactions. However, achieving sensitive and more comprehensive monitoring of gas-phase compounds with different ionization energies in a single measurement remains a significant challenge. In this work, a multiphysics ion trajectory simulation integrating a coupled computational fluid dynamics-direct simulation Monte Carlo (CFD-DSMC) method for continuum-rarefied flow was carried out for tracing the ion motion within the ionization region. The simulation results were applied to the design of the cage lens assembly of a modified SR-PIMS, and a limit of detection (LOD) of 0.67 ppbv (S/N ≥ 3) was achieved under Kr-lamp calibration conditions for toluene. Furthermore, a residual gas analyzer (RGA) was coupled to the SR-PIMS for the complementary detection of organic products with low ionization energies (IEs, generally lower than 11 eV) and H2, CO, CO2 etc. with higher IEs, thereby reducing the need for separate measurements at multiple photon energies. The optimized SR-PIMS setup combined with RGA was successfully applied to probe the intermediates and products generated during the methanol-to-hydrocarbons (MTH) reaction over ZnO/HZSM-5 catalysts, and the time-evolved profiles for major species under different ZnO loadings were obtained and analyzed.

The aluminum@ammonium perchlorate (Al@AP) composite can improve the combustion performance of solid propellants, but Al and AP are difficult to form the Al@AP composite without an intermediate medium. The assembly and interface formation mechanism of the intermediate medium at the interface of Al and AP is a grey area. In this study, the adsorption behavior of the polydopamine (PDA) monomer on the Al (1 1 1) surface with different oxygen coverage was investigated by DFT calculations. The composite energetic particles of Al@AP are assembled under the synergy of the Al (1 1 1) surface and the PDA layer to achieve adhesion to AP molecules. The coating of PDA on the surface of Al particles was quantitatively analyzed through molecular dynamics and experimental verification. The roles of different PDA monomers in the coating process are dissimilar, and PDA realizes the close contact between Al and AP by enhancing the electrostatic interaction at the interface. This study provides a favorable theoretical foundation for the preparation of Al-based composite energetic particles used in solid propellants.

The low-temperature oxidation kinetics of ethanol were investigated in an argon-diluted atmosphere using a nanosecond-pulsed dielectric barrier discharge (DBD) in a plasma flow reactor at 340 K and 20 Torr. Species were identified and quantified using photoionization molecular beam mass spectrometry (PI-MBMS). This diagnostic technique effectively minimizes post-sampling reactions and preserves reactive species, enabling the detection of both stable molecules and radicals. Intermediates identified in the experiments include methane (CH4), water (H2O), acetylene (C2H2), carbon monoxide (CO), ethylene (C2H4), formaldehyde (CH2O), methanol (CH3OH), ketene (CH2CO), carbon dioxide (CO2), acetaldehyde (CH3CHO), methyl hydroperoxide (CH4O2), acetic acid (CH3COOH), and methyl acetate (CH3COOCH3). Furthermore, a kinetic mechanism for plasma-assisted low-temperature ethanol oxidation was developed and validated against the experimental results. Rate-of-production (ROP) analysis revealed that the plasma-induced reaction e/Ar* + C2H5OH -> e/Ar + C2H5O + H serves as an important pathway for ethanol decomposition. The generated alkoxy radicals subsequently undergo the reaction C2H5O -> CH3 + CH2O, which promotes direct oxygen addition CH3 + O-2 (+M) -> CH3O2 (+M), leading to peroxide formation. These results demonstrate that DBD plasma effectively activates ethanol oxidation at low temperature of 340 K. Novelty and significance statement This study employs synchrotron vacuum ultraviolet photoionization molecular beam mass spectrometry (SVUV-MBMS) to diagnose species in the plasma-assisted oxidation of ethanol, enabling the detection of a wide range of intermediates, including both radicals and stable molecules. The present study notably detected peroxides and esters that had not been previously reported in plasma-driven ethanol oxidation. Based on the experimental data, a kinetic mechanism was developed, and the reaction pathways for ethanol consumption, as well as the formation of products and intermediates, were revealed. Given that the kinetics of plasma-assisted alcohol oxidation remain poorly understood and detailed species diagnostics are scarce, this study provides unique species-resolved information essential for elucidating the reaction kinetics in such systems. The results offer critical experimental evidence and kinetic insights into the plasma-assisted oxidation pathways of ethanol, supplying valuable data for mechanism development and modeling.

Radical-radical reactions of resonantly stabilized species such as propargyl (C3H3˙) and benzyl (C7H7˙) efficiently generate polycyclic aromatic hydrocarbons (PAHs). Key mechanisms-propargyl addition-benzannulation (PABA), methyl addition-ring expansion (MARE), and cyclopentadienyl addition-naphthylization (CPAN)-govern early-stage aromatic growth, but transforming these mechanisms to larger PAHs is computationally challenging due to combinatorial intermediates and reactions on excited state triplet surfaces. Here, we introduce a "periodic system" of PAHs that organizes aromatic growth according to transferable radical-radical motifs, enabling prediction of molecular evolution across the size regime. Using (2-naphthyl)-methyl (2-C11H9˙) and benzyl (C7H7˙) radicals as benchmarks, we experimentally demonstrate the predicted gas-phase formation of four- and five-ring PAHs, including (1) C18H12 isomers: tetracene, benz[a]anthracene, and [4]helicene; (2) C22H14 isomers: benzo[a]tetracene, benzo[a]tetraphene, and [5]helicene. Secondary hydrogen-loss and successive reactions produce even larger 2D and 3D aromatics, such as nanobowls and fullerenes, and their building blocks (corannulene and coronene). This framework provides a unifying and predictive description of PAH growth across combustion and circumstellar environments such as carbon-rich envelopes of late-type Asymptotic Giant Branch (AGB) stars and planetary nebulae.

RATIONALE:The ion motion within a mass spectrometer is governed by the coupling of gas dynamics and electric fields. Therefore, a comprehensive understanding of ion transport from atmospheric pressure to the high-vacuum mass analyzer is crucial. METHODS:In this work, a hybrid computational fluid dynamics-direct simulation Monte Carlo (CFD-DSMC) strategy was employed to accurately resolve the cross-scale flow fields spanning from the continuum to the rarefied regime in the mass spectrometer. Subsequently, a multiphysics model integrating gas dynamics, electric fields, and ion trajectories was developed to achieve high-precision predictions of ion transport behavior. RESULTS:To validate the accuracy of the theoretical simulation, ion transmission efficiencies of acetone and toluene were experimentally measured using a homemade low-pressure photoionization time-of-flight mass spectrometer (LPPI-TOF-MS). The experimental results demonstrated a strong correlation with the simulation predictions, achieving a maximum Pearson correlation coefficient (r) of 0.96 for toluene and 0.90 for acetone in the radio-frequency-only quadrupole (RFQ) region, confirming the model's reliability. CONCLUSIONS:This study provides a robust theoretical tool for elucidating ion transport mechanisms and guiding the optimization of ion optics in mass spectrometers.

The low-temperature oxidation (340 K, 30 Torr) kinetics of n-propanol and isopropanol under nanosecond pulsed dielectric barrier discharge (DBD) in argon dilution were investigated using a combination of plasma flow reactor experiments and numerical simulations. Species identification and quantification were performed via photoionization molecular beam mass spectrometry (PI-MBMS). This technique can effectively minimize post-sampling collisions and preserve active components, enabling the detection of both stable molecules and reactive species such as radicals. Intermediates including CH3, CH4, CH2O, CH3CHO, C2H5CHO, CH3COCH3, CH2CO, C2H2, C2H4, C3H4, C3H6, CH3OH, C2H5OH and C3H5OH in the present systems were experimentally determined. Species mole fractions as functions of inlet O-2 concentrations were measured. As the inlet O-2 concentration increased, the mole fractions of several oxygenated products, including CO2, CH2O, CH3CHO, and C2H5CHO were observed to flatly increase, while those of unsaturated hydrocarbons such as C2H4 were independent of inlet O-2. Additionally, a reaction kinetic mechanism for the plasma-assisted low-temperature oxidation of propanol isomers was established and validated against experimental results. Rate-of-production (ROP) analysis revealed the dominant reaction pathways for the consumption of both n-propanol and isopropanol, as well as the formation of key intermediates and products. Under plasma conditions, the excited-state reactions Ar* + n/isoC(3)H(7)OH Ar + n/isoC(3)H(7)O + H serves as the primary pathway for propanol decomposition, with the hydrogen abstraction site being strongly dependent on the isomeric structure of propanol. The subsequent reactions n/isoC(3)H(7)OCH(2)O+C2H5/CH3CHO+CH3 also account for the differences observed in the oxidation product distributions of the propanol isomers. Novelty and significance statement The novelty of this study lies in the first investigation of plasma-assisted propanol oxidation kinetics by combining detailed species diagnostics with kinetic modeling. In present study, 17 species were first identified in the plasma of n-propanol and 16 species in the plasma of isopropanol, including CH3, CH4, CH2O, CH3CHO, C2H5CHO, CH3COCH3, CH2CO, C2H2, C2H4, C3H4, C3H6, CH3OH, C2H5OH and C3H5OH, providing new insights into the underlying reaction kinetics. A detailed kinetic mechanism of plasma-assisted propanol oxidation system was developed for the first time and validated against experimental observations. Isomeric effect was revealed via reaction pathway analysis, i.e., the oxidation pathways are strongly influenced by the alcohol molecular structure. Differences in hydrogen abstraction sites, coupled with bond cleavage between the alpha- and beta-carbons, results in distinct product distributions for the two isomers.

BACKGROUND:Online analysis of complex gas mixtures is often hindered by spectral congestion resulting from extensive fragmentation in traditional electron ionization (EI) sources. Although photoionization (PI) provides clean mass spectra by preserving molecular ion integrity, its comprehensive detection is limited by an inherent ionization selectivity toward species with low ionization energies. METHODS:To address these challenges, a dual-ionization source quadrupole mass spectrometer (DISQMS) integrating PI and EI was developed. Its design and optimization were guided by a multiphysics ion trajectory simulation method coupling continuum-rarefied flow fields with electric fields. The flow field, spanning from the sampling capillary to the quadrupole mass analyzer chamber, was numerically simulated using a hybrid computational fluid dynamics-direct simulation Monte Carlo (CFD-DSMC) method. RESULTS:Guided by the simulation, the key instrumental parameters were systematically optimized, and the reliability of the simulation model was validated experimentally. During the detection of acetone, benzene, and air mixtures, clean organic spectra were obtained in PI mode, whereas comprehensive detection of inorganic gases with high ionization energies (e.g., N2 and O2) and detailed fragment-ion information were achieved in EI mode. CONCLUSIONS:A DISQMS was developed and validated, and a multiphysics ion trajectory simulation framework was proposed to numerically optimize the instrument's sensitivity. It was demonstrated that complementary detection of organic and inorganic species is achieved through the dual-mode capability. Specifically, spectral interpretation and molecular structure elucidation are effectively facilitated by combining the detailed fragment-ion information from EI with the clean molecular ion data from PI.

Although both aluminum/polyvinylidene fluoride (Al/PVDF) and aluminum/polytetrafluoroethylene (Al/PTFE) systems exhibit excellent combustion performance, the study on comparing their combustion behaviors and the underlying mechanisms responsible for their differences are still relatively limited. Therefore, the advantages and disadvantages of the Al/PVDF and Al/PTFE systems were compared through ignition experiments and molecular dynamics simulations. The Al/PTFE system exhibits higher combustion intensity, and the characteristic is attributed to the higher fluorine (F) content in PTFE, which triggers more Al-F reactions. In contrast, the Al/PVDF system exhibits a lower ignition delay time and higher combustion heat, which is attributed to the relatively lower initial decomposition temperature, the higher hydrogen (H) content, and the higher combustion heat in PVDF. Compared to oxygen (O) atoms, H atoms can penetrate the oxide film on the surface of Al particles more rapidly and react with the inner Al atoms, thereby reducing the temperature required for Al atoms to break through the oxide film and participate in reactions.

RATIONALE:While ambient mass spectrometry imaging (MSI) is essential for biological analysis, its sensitivity remains constrained by ion transmission losses due to collisions and gas dynamics. METHODS:Here, a high-performance desorption electrospray ionization (DESI) MSI system featuring a high-efficiency dual-stage ion funnel (DIF) was developed. To optimize the system configuration, a hybrid multiphysics simulation model was constructed by coupling gas dynamics, electric field, and ion transport simulations. RESULTS:The simulation model was validated against experimental data from mouse brain homogenates, confirming its accuracy in predicting ion transport behavior under realistic conditions. With the optimized DIF assembly, signal enhancements of up to 490-fold and the detection of 303 additional mass peaks in mouse brain sections were achieved compared to the standard S-lens interface. Furthermore, post-photoionization (PI) was introduced to expand molecular coverage to non-polar compounds and simultaneously enhance sensitivity. CONCLUSIONS:Overall, this study provides theoretical insights into ion motion within complex coupled fields and offers guidelines for the design of high-sensitivity ambient MSI interfaces.

While thermal destruction remains one of the most effective treatments for ultrashort-chain per- and polyfluoroalkyl substances (PFAS) such as trifluoroacetic acid (TFA) at full scale, their evolution during incineration processes remains poorly understood, particularly those promoted by material surfaces in contact with the PFAS stream. Here we resolve the intrinsic and surface-mediated mechanisms of the pyrolysis of TFA and its non-PFAS analogue difluoroacetic acid (DFA) using synchrotron vacuum-ultraviolet photoionization mass spectrometry. Both compounds decompose primarily via HF elimination followed by decarboxylation or decarbonylation. Surprisingly, alumina surfaces facilitate the elimination of HF from TFA, but promote the formation of tetrafluoroethylene and perfluorocyclopropane as products of incomplete destruction (PIDs) from a bottom-up growth of CF2. These findings suggest that perfluorocyclopropane may serve as a promising indicator of surface-catalyzed recombination reactions during full-scale incineration. In contrast, DFA generates hydrogen-containing intermediates that undergo rapid secondary reactions, suppressing the formation of PIDs and enhancing overall incinerability. Our findings provide benchmark mechanistic insight into ultrashort-chain PFAS decomposition and call for systematic evaluation of surface effects that promote PID formation.

The flue gas emitted from industrial processes, which contains nitrogen oxides (NOx) and volatile organic compounds (VOCs), poses significant environmental challenges. The development of low-temperature catalysts with the simultaneous removal of NOx and VOCs through selective catalytic reduction (SCR) remains a key challenge. In this study, to achieve efficient synergistic removal of NOx and toluene (SR), a mechanochemical method was proposed for the preparation of a Ce-MnO2 catalyst. Compared with other methods, the catalyst prepared by the mechanochemical method has more oxygen vacancies, surface active sites, and a higher proportion of Ce3+ and Oads. These structural advantages result in the excellent removal efficiency for both individual and synergistic NOx and VOCs. Specifically, the catalyst exhibits the widest high-efficiency (above 90% conversion) SCR reaction temperature window, the lowest T90 of toluene removal (T90 is the temperature when the conversion of toluene reaches 90%) and reaction activation energy, and the synergistic removal conversions of NOx and toluene are more than 90% at 185-240 degrees C. The density functional theory (DFT) reveals that the two reactants (toluene and NH3) are competitively adsorbed on the surface of the Ce-MnO2 catalyst, which decreases the synergistic removal efficiency of NOx and toluene. However, at elevated temperatures, the by-products such as NO2 can promote the redox of toluene and reduce the T90 of toluene removal. These findings demonstrate that the mechanochemical method is not only a simple and rapid approach for preparing catalysts, but also successfully prepares the Ce-MnO2 catalyst with superior bifunctional performance for NOx and toluene abatement, which provides a promising method for the development of advanced catalysts with synergistic removal pollutants.

Abstract The BL01 beamline at the Hefei Advanced Light Facility (HALF) is a dedicated vacuum ultraviolet (VUV) photoionization mass spectrometry beamline designed for energy conversion and astrochemistry research. Operating in the 5–20 eV photon energy range, BL01 employs a 4.2-m hybrid undulator (HU115) as its light source on a 2.2 GeV fourth-generation storage ring with an emittance below 100 pm·rad. The beamline features a dual-branch configuration (white-light and monochromatic branches) using a Monk–Gillieson monochromator with two variable-line-spacing plane gratings (150 and 300 lines/mm). The white-light branch is designed to deliver a photon flux of 1.0 × 1016 phs/s at 4% bandwidth and 10 eV, while the monochromatic branch is designed to achieve an energy resolution of 5000 at 15 eV with a photon flux of 2.0 × 1013 phs/s at a resolving power of 2000. Three dedicated endstations─combustion chemistry, catalysis chemistry, and astrochemistry─are equipped with high-resolution time-of-flight mass spectrometers (mass resolution ≥5000, detection limit 0.1 ppm), enabling in-situ detection of trace reaction intermediates across wide temperature (5–2000 K) and pressure (10–8 Pa to 20 bar) ranges. The high flux is expected to provide competitive advantages over existing international VUV photoionization beamlines, with a three- to ten-fold improvement in photon flux. The beamline is currently under construction, with completion expected in 2028.

Given its extensive industrial use and adverse effects on human health, trichloroethylene (TCE) is a priority environmental pollutant and a Group 1 carcinogen (IARC). Understanding its transformation under thermal conditions is essential for evaluating environmental risks associated with thermal remediation and incineration. Herein, the thermal pyrolysis of TCE was investigated in a flow-tube reactor using in situ synchrotron radiation photoionization mass spectrometry (SR-PIMS) to directly detect reactive radicals and short-lived intermediates. Key transient species, including methyl radical (•CH3), propargyl radical (•C3H3), chloromethyl radical (•CH2Cl), chloro-cyclopentadienyl radical (•C5H4Cl), chlorocyclopentadiene (C5H5Cl), and trichloromethyl radical (•CCl3), and small molecular intermediates, were identified by their mass-to-charge ratios and photoionization efficiency (PIE) spectra. A comprehensive reaction network was constructed, encompassing initial TCE decomposition and subsequent radical-driven and molecular combination pathways leading to chlorinated and non-chlorinated aromatic species. Initial decomposition proceeds primarily through homolytic C–Cl cleavage. Chlorinated species, including C2Cl2, C2Cl4, C4Cl4, C3Cl6, C4Cl6, C5Cl6, C6Cl6, and C8Cl6, were major products at 923–1173 K and 760 Torr, while others were present in trace amounts. Reduced pressure (30 Torr) suppressed aromatic formation and favored smaller molecular species. This work provides a mechanistic framework for chlorinated hydrocarbon transformation and highlights SR-PIMS capability to probe transient intermediates in complex pyrolytic systems. Furthermore, these findings may help predict toxic byproduct formation during thermal treatment of chlorinated solvents and provide mechanistic insights relevant to emission control and remediation design.

Trichloroethylene (TCE) is a widely used solvent in industrial processes, which is harmful to human health and the environment. Photocatalysis is a promising method for the degradation of TCE. In this work, the photocatalytic reaction of TCE over TiO2 was studied using synchrotron radiation photoionization mass spectrometry (SR-PIMS) under 360 nm UV light irradiation. First, more than 12 kinds of gas phase degradation intermediates and products were detected, including newly identified products such as formaldehyde (HCHO), formic acid (HCOOH) and hypochlorous acid (HOCl) and tetrachloroethane (C2H2Cl4). Second, the effects of water and oxygen on the photocatalysis of TCE over TiO2 were investigated. It was found that water vapor showed a negligible effect on the photocatalytic degradation efficiency TCE, but could enhance the generation of oxygen-containing species, like hypochlorous acid (HOCl), Phosgene (COCl2), and dichloroacetyl chloride (C2HOCl3). The presence of oxygen in the gas phase significantly enhanced the photocatalytic degradation of TCE, due to its role as an electron acceptor, preventing the recombination of photogenerated electron-hole pairs on the TiO2 surface, thereby enhancing the generation of reactive species like superoxide radicals (O2•-), which are essential for the effective degradation of TCE. Finally, the photocatalytic degradation network of TCE over TiO2 was proposed.

Natural manganese-iron ore calcined in an argon atmosphere was employed as a catalyst, which exhibits toluene and NO conversion rates of 100 % and 85 %, respectively, at 240 degrees C, along with high selectivity of N2 and CO2. However, the interaction mechanisms among the gas components remain unclear. To explore the underlying mechanisms by which NH3 and NO influence toluene adsorption and oxidation, a combined study involving experimental techniques and first-principles calculations was carried out. The results reveal that NO tends to form stable by-products on the catalyst surface, which inhibit toluene oxidation. NH3 competes with toluene for adsorption sites. However, with increasing temperature, NH3 can effectively eliminate NO-derived by-products, thereby restoring the concentration of surface-active oxygen and the number of active sites. Through this process, a highly efficient low-temperature synergistic removal of toluene and NO can be realized.

Thermal destruction is a critical cornerstone of addressing the rampant contamination of natural resources with per- and polyfluoroalkyl substances (PFAS). However, grave concerns associated with stack emissions from incineration exist because mechanistic studies have thus far relied on ex situ analyses of end products and theoretical calculations. Here, we used synchrotron-based vacuum ultraviolet photoionization mass spectrometry to study the pyrolysis of a representative PFAS-perfluorohexanoic acid-and provide direct evidence of fluorocarbon radicals and intermediates. A key reaction pathway from perfluorocarboxylic acids to ketenes via acyl fluorides is proposed. We furthermore propose CF2/CF3 radical-centered pyrolysis mechanisms and explain their roles in the formation of other products that may form in full-scale incinerators. These results have not only unveiled the role of radicals and intermediates in thermal PFAS decomposition and recombination mechanisms but also provide unique insight into improving the safety and viability of industrial PFAS incineration.

The methane dehydroaromatization (MDA) reaction is crucial for converting methane into valuable aromatics but involves harsh conditions and complex intermediates. This study utilized advanced in situ synchrotron radiation photoionization mass spectrometry (SR-PIMS) to monitor the 6 wt % molybdenum (Mo)-loaded catalyst and intermediate behaviors in real time. Significant insights include the direct detection of highly reactive radicals [methyl (center dot CH3), and specifically carbene (center dot CH2)] and organic oxygenated species [methanol (CH3OH), methoxy radical (center dot OCH3), and formaldehyde (HCHO)], as well as insights into the two-step activation and deoxygenation processes at molybdenum (Mo) sites. The study also captured coke deposition and elimination dynamics, confirming significant acetylene production as a key precursor for aromatics. The Mo site activation and gas-phase species generation occur in two stages: initially, Mo oxides are deoxygenated and activated by methane with the production of methanol and formaldehyde as the organic oxygenated intermediates. Methane is then dehydrogenated by the active sites, yielding carbene and methyl radicals, which promote the further activation of Mo sites, driving coke elimination and promoting the formation of C2 hydrocarbons, including acetylene and ethylene. The work sheds light on the catalytic mechanism, offering valuable guidance for designing more efficient MDA catalysts.

Natural manganese-iron ore was utilized to prepare catalysts with varying amounts of oxygen vacancies and surface adsorbed oxygen content by regulating the calcination atmosphere, aiming to achieve the efficient low-temperature synergistic removal of NO and toluene (C7H8). Calcination under an Ar atmosphere significantly enhances both oxygen vacancy concentration and surface adsorbed oxygen content of the manganese-iron-based catalyst (MIN-Ar). Under the coexistence of NO and toluene, the MIN-Ar catalyst achieves the complete removal of C7H8 at 240 degrees C, and maintains NO conversions above 80 % at 100-260 degrees C. Density functional theory (DFT) calculations reveal that the catalytic oxidation reactions are more favorable on the MnO2 surfaces with oxygen vacancies, while NH3-SCR reactions are more likely to occur on the oxygen-deficient Fe2O3 surfaces. Competitive adsorption between NH3 and C7H8 exhibits a detrimental effect on both the C7H8 catalytic oxidation and the NH3-SCR process. The oxygen vacancies significantly reduce the energy barrier for O2 dissociation, thereby promoting oxygen activation and redox cycling. This study provides an effective strategy for developing manganese-iron ore-based catalysts that are capable of achieving highly efficient low-temperature synergistic removal of NO and C7H8.