Role of Structural Defects in MnOx Promoted by Ag Doping in the Catalytic Combustion of Volatile Organic Compounds and Ambient Decomposition of O3

Catalytic oxidation of volatile organic compounds over supported noble metal and single atom catalysts: A review

Volatile organic compounds (VOCs) exhausted from industrial processes are the major atmospheric pollutants, which could destroy the ecological environment and make hazards to human health seriously. Catalytic oxidation is regarded as the most competitive strategy for the efficient elimination of low-concentration VOCs. Supported noble metal catalysts are preferred catalysts due to their excellent low-temperature catalytic activity. To further lower the cost of catalysts, single atom catalysts (SAC) have been fabricated and extensively studied for application in VOCs oxidation due to their 100 % atom-utilization efficiency and unique catalytic performance. In this review, we comprehensively summarize the recent advances in supported noble metal (e.g., Pt, Pd, Au, and Ag) catalysts and SAC for VOCs oxidation since 2015. Firstly, this paper focuses on some important influencing factors that affect the activity of supported noble metal catalysts, including particle size, valence state and dispersion of noble metals, properties of the support, metal oxide/ion modification, preparation method, and pretreatment conditions of catalysts. Secondly, we briefly summarize the catalytic performance of SAC for typical VOCs. Finally, we conclude the key influencing factors and provide the prospects and challenges of VOCs oxidation.

POM-promoted synergistic catalysis of NO and chlorobenzene over amorphous MnCeOx catalysts: Activation of lattice oxygen, role of acid site, catalytic mechanism

The release rate of lattice oxygen and surface acidic sites are key factors for the multi-pollutant synergistic catalysis such as nitrogen oxides (NOx) and chlorine-containing volatile organic compounds (Cl-VOCs). In this study, a polyoxometalate (POM)-assisted strategy was employed to optimize the synergistic catalytic performance of MnCeOx for NO and chlorobenzene. The strong proton conductivity of the surface POM structure effectively suppresses the deposition of chlorinated species, preventing the poisoning of active sites. Specifically, POM-SiW structure can act as a dechlorination site in place of Mn3O4 and exhibits the highest density of acidic sites and oxygen vacancies, leading to a reduction of the T90 for chlorobenzene to 167 ℃ and an expansion. The assistance of POM-SiW structure facilitates the electron transfer from POM-SiW to lattice oxygen (Olat), resulting in reduced orbital overlap between Mn and O atoms, thereby weakening the Mn-O bond and activating Olat. Furthermore, in-situ DRIFTs, TOF-SIMS and DFT results confirmed that POM-SiW structure can inhibit the competitive adsorption of NO, NH3 and chlorobenzene, NO2 and NH4+ act as additional oxidants and dechlorinating agents, effectively promoting the catalytic decomposition of chlorobenzene and its intermediate products. This work provides a novel strategy for catalyst design in low-temperature multi-pollutant synergistic catalysis.

In Situ Generation of Porous Ag-Hollandite/Polypyrrole 2D Mats at the Water/Chloroform Interface for Dual Applications in Energy Storage and Electrochemical Sensing

A facile in situ method of the liquid/liquid (L/L) polymerization strategy for synthesizing silver-doped hollandite manganese oxide (Ag-HMO) on polypyrrole (PPy) support is reported for the first time. The highly innovative synthetic method involves producing α-MnO2 attached to PPy oligomers under low-temperature conditions. Subsequently, Ag+ ions are in situ intercalated into the 2 × 2 tunnels in α-MnO2 to generate Ag-HMO-incorporated PPy. Calculations based on density functional theory (DFT) yield negative formation energies, suggesting that Ag-HMO can be formed through the tunnel doping of Ag+ in α-MnO2. Highly crystalline 2D composite mats of Ag-HMO/PPy (PAgMn) with interconnected Ag-HMO nanorod networks with a thickness of ≈1 nm are demonstrated by electron and atomic force microscopy images. Electrochemical detection of formaldehyde on PAgMn-modified screen-printed electrodes opens new prospects for real-time food adulterant sensors. PAgMn is also utilized as electrodes for supercapacitors with a high specific capacitance of 601 mF cm-2. An all-solid-state asymmetric supercapacitor device assembled with PAgMn and activated carbon as negative and positive electrodes demonstrates outstanding energy storage capability with a remarkable energy density of 6.16 mWh cm-2 at a power density of 6300 mW cm-2.

Defect-based Lewis pairs on hydrophobic MnO mesocrystals for robust and efficient ozone decomposition

Catalytic ozone decomposition is a promising technique for eliminating ozone from the environment. However, developing redox-active catalysts that efficiently decompose ozone while maintaining robust performance under high humidity remains challenging. Herein, we develop a hydrophobic carbon-coated mesocrystalline MnO (Meso-MnO@C) featuring a high density of manganese vacancies (VMn)-based Lewis pairs (LPs) for catalytic ozone decomposition. The presence of VMn induces the electronic restructuring in MnO, leading to the formation of VMn-Mn acidic sites and adjacent lattice oxygen atoms as basic sites. These LPs act as electron donors and acceptors, facilitating rapid electron transfer and lowering the energy barrier for O3 conversion to O2. The hydrophobic carbon layer protects against water accumulation on Meso-MnO@C in humid conditions. As a result, the Meso-MnO@C achieves nearly 100% O3 decomposition at a high weight hourly space velocity of 1500 L⋅g-1 h-1, with rapid reaction kinetics and stable performance for 100 hours under 65% relative humidity.

Combined Catalytic Conversion of NOx and VOCs: Present Status and Prospects

This article presents a comprehensive examination of the combined catalytic conversion technology for nitrogen oxides (NOx) and volatile organic compounds (VOCs), which are the primary factors contributing to the formation of photochemical smog, ozone, and PM2.5. These pollutants present a significant threat to air quality and human health. The article examines the reaction mechanism and interaction between photocatalytic technology and NH3-SCR catalytic oxidation technology, highlighting the limitations of the existing techniques, including catalyst deactivation, selectivity issues, regeneration methods, and the environmental impacts of catalysts. Furthermore, the article anticipates prospective avenues for research, underscoring the necessity for the development of bifunctional catalysts capable of concurrently transforming NOx and VOCs across a broad temperature spectrum. The review encompasses a multitude of integrated catalytic techniques, including selective catalytic reduction (SCR), photocatalytic oxidation, low-temperature plasma catalytic technology, and biological purification technology. The article highlights the necessity for further research into catalyst design principles, structure-activity relationships, and performance evaluations in real industrial environments. This research is required to develop more efficient, economical, and environmentally friendly waste gas treatment technologies. The article concludes by outlining the importance of collaborative management strategies for VOC and NOx emissions and the potential of combined catalytic conversion technology in achieving these goals.

A Critical Review of Deep Oxidation of Gaseous Volatile Organic Compounds via Aqueous Advanced Oxidation Processes

Volatile organic compounds (VOCs) are considered to be the most recalcitrant gaseous pollutants due to their high toxicity, diversity, complexity, and stability. Gas-solid catalytic oxidation methods have been intensively studied for VOC treatment while being greatly hampered by energy consumption, catalyst deactivation, and byproduct formation. Recently, aqueous advanced oxidation processes (AOPs) have attracted increasing interest for the deep oxidation of VOCs at room temperature, owing to the generation of abundant reactive oxygen species (ROS). However, current reviews mainly focus on VOC degradation performance and have not clarified the specific reaction process, degradation products, and paths of VOCs in different AOPs. This study systematically reviews recent advances in the application of aqueous AOPs for gaseous VOC removal. First, the VOC gas-liquid mass transfer and chemical oxidation processes are presented. Second, the latest research progress of VOC removal by various ROS is reviewed to study their degradation performances, pathways, and mechanisms. Finally, the current challenges and future strategies are discussed from the perspectives of synergistic oxidation of VOC mixtures, accurate oxidation, and resource utilization of target VOCs via aqueous AOPs. This perspective provides the latest information and research inspiration for the future industrial application of aqueous AOPs for VOC waste gas treatment.

Revealing the intrinsic nature of Cu- and Ce-doped Mn3O4 catalysts with positive and negative effects on CO oxidation using operando DRIFTS-MS

Aiming at the problem of the poor performance of an Mn-MOF-74-derived Mn3O4 catalyst in low-temperature carbon monoxide (CO) oxidation, copper (Cu) and cerium (Ce) elements were used to modify the Mn3O4 catalyst to improve its performance in low-temperature CO oxidation. According to the results of catalytic performance testing, the CO oxidation activity of the Cu0.3Mn2.7O4 catalyst was significantly improved compared with that of the pristine Mn3O4 catalyst, when a CO conversion rate of 90% was achieved at 118 °C. According to X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller analyses, the (Mn2+ + Mn3+)/(Mn2+ + Mn3+ + Mn4+) ratio and the Oads/Ototal ratio increased after Cu doping, indicating promoted oxygen vacancy generation. In addition, the increased specific surface area was beneficial for the adsorption of reactant molecules and the exposure of active sites. According to H2-temperature-programmed reduction characterization, Cu doping significantly enhanced the performance of the Cu0.3Mn2.7O4 catalyst during low-temperature redox. Finally, these factors synergistically promoted the degradation of CO over the Cu0.3Mn2.7O4 catalyst. In addition, operando diffuse reflectance Fourier transform infrared spectroscopy results suggested the presence of more terminal-type oxygen, which is essential for the catalytic oxidation of CO on the surface of the Cu0.3Mn2.7O4 catalyst. Moreover, the Cu0.3Mn2.7O4 catalyst also showed excellent resistance to carbonate, and remarkable stability.

Synthesis Ag-Hollandite by mild route for highly efficient ozone decomposition

Catalytic ozone (O3) decomposition is a promising technology for curbing indoor O3 pollution, whereas its application is limited by the stability and moisture resistance of heterogeneous catalysts. Ag-Hollandite is a capable solution, but its facile synthesis still lacks systematic investigation. In this study, Ag-Hollandite catalysts were prepared using AgMnO4 as the precursor by reflux (AMO-Re), hydrothermal (AMO-HT), and homogeneous (AMO-HR) methods, respectively. The as-prepared samples showed excellent stability under moisture conditions, with the optimal one maintaining an O3 conversion rate of 99.19 % after 100 h. In the characterization results, Ramsdellite (R-MnO2) was identified as an intermediate species in the synthesis. AMO-HR exhibits higher activity due to enhanced active site exposure and weakened adsorption towards *OO species, while reduced surface hydroxyl content was a crucial factor for moisture resistance. This study aims to contribute insights for preparing catalysts by a facile method.

Efficacious destruction of typical aromatic hydrocarbons over CoMn/Ni foam monolithic catalysts with boosted activity and water resistance

Developing cost-effective monolith catalyst with superior low-temperature activity is critical for oxidative efficacious removal of industrial volatile organic compounds (VOCs). However, the complexity of the industrial flue gas conditions demands the need for high moisture tolerance, which is challenging. Herein, CoMn-Metal Organic Framework (CoMn-MOF) was in situ grown on Ni foam (NiF) at room temperature to synthesize the cost-effective monolith catalyst. The optimized catalyst, Co1Mn1/NiF, exhibited excellent performance in toluene oxidation (T90 = 239 °C) due to the substitution of manganese into the cobalt lattice. This substitution weakened the Co-O bond strength, creating more oxygen vacancies and increasing the active oxygen species content. Additionally, experimentally and computationally evidence revealed that the mutual inhibiting effect of three typical aromatic hydrocarbons (benzene, toluene and m-xylene) over the Co1Mn1/NiF catalyst was attributed to the competitive adsorption occurring on the active site. Furthermore, the Co1Mn1/NiF catalyst also presents outstanding water resistance, particularly at a concentration of 3 vol%, where the activity is even enhanced. This was attributed to the lower water adsorption and dissociation energy derived from the interaction between the bimetals. Results demonstrate that the dissociation of water vapor enables more reactive oxygen species to participate in the reaction which reduces the formation of intermediates and facilitates the reaction. This investigation provides new insights into the preparation of oxygen vacancy-rich monolith catalysts with high water resistance for practical applications.

Mullite-like SmMn2O5-Derived Composite Oxide-Supported Ni-Based Catalysts for Hydrogen Production by Auto-Thermal Reforming of Acetic Acid

The x%Ni/Sm2O3-MnO (x = 0, 10, 15, 20) catalysts derived from SmMn2O5 mullite were prepared by solution combustion and impregnation method; auto-thermal reforming (ATR) of acetic acid (HAc) for hydrogen production was used to explore the metal-support effect induced by Ni loadings on the catalytic reforming activity and product distribution. The 15%Ni/Sm2O3-MnO catalyst exhibited optimal catalytic performance, which can be due to the appropriate Ni loading inducing a strong metal-support interaction to form a stable Ni/Sm2O3-MnO active center, while side reactions, such as methanation and ketonization, were well suppressed. According to characterizations, Sm2O3-MnO mixed oxides derived from SmMn2O5 mullite were formed with oxygen vacancies; nevertheless, loading of Ni metal further promoted the formation of oxygen vacancies, thus enhancing adsorption and activation of oxygen-containing intermediate species and resulting in higher reactivity with HAc conversion near 100% and hydrogen yield at 2.62 mol-H2/mol-HAc.

Enhancement Effect Induced by the Second Metal to Promote Ozone Catalytic Oxidation of VOCs

It is a promising research direction to develop catalysts with high stability and ozone utilization for low-temperature ozone catalytic oxidation of VOCs. While bimetallic catalysts exhibit excellent catalytic activity compared with conventional single noble metal catalysts, limited success has been achieved in the influence of the bimetallic effect on the stability and ozone utilization of metal catalysts. Herein, it is necessary to systematically study the enhancement effect in the ozone catalytic reaction induced by the second metal. With a simple continuous impregnation method, a platinum-cerium bimetallic catalyst is prepared. Also highlighted are studies from several aspects of the contribution of the second metal (Ce) to the stability and ozone utilization of the catalysts, including the "electronic effect" and "geometric effect". The synergistic removal rate of toluene and ozone is nearly 100% at 30 °C, and it still shows positive stability after high humidity and a long reaction time. More importantly, the instructive significance, which is the in-depth knowledge of enhanced catalytic mechanism of bimetallic catalysts resulting from a second metal, is provided by this work.

Enhanced water resistance mechanism in Ag-Hollandite for catalytic ozone decomposition

Catalytic ozone (O3) decomposition at ambient temperature is an efficient method to mitigate O3 pollution. However, practical application is hindered by the poor water resistance of catalysts. Herein, Ag-Hollandite (Ag-HMO) with varying Ag+ content was synthesized. Catalysts with more Ag+ exhibited improved efficiency and water-resistance, with the optimal one maintaining 98% O3 conversion at 70% relative humidity (RH) within 8 h. Physicochemical characterizations revealed that Ag+ had entered the tunnel of OMS-2, facilitating oxygen species removal. Notably, enhanced H2O desorption and the complete inhibition of chemisorbed water formation on Ag-HMO were the primary reasons for its high-efficiency O3 conversion across a wide humidity range. The underlying mechanism arises from the charge redistribution induced by the Ag-O interaction within the tunnel, which reduces acidity and modulates hydrophilicity. This study aims to contribute insights for designing catalysts with higher water-resistance.

Highly sensitive detection of glucose at a novel non-enzyme electrochemical sensing based on Mo-doped CoO Nanosheets

In this work, a Mo doped CoO nanosheet grown on nickel foam (labeled as: Mo-CoO) with defect-rich and improved electron transfer capacity was designed to be used as a novel non-enzyme electrode material. Physical characterizations demonstrated the Mo elements were doped inside of the samples and they were mutually stabilized with each other, resulting in a high structural stability electrochemical catalytical activity even if the content of Mo was low. For non-enzymatic glucose electrochemical sensing, the prepared Mo-CoO-1 showed a remarkable sensitivity of 89.3 mA cm-2  mM-1 , and a low detection limit of 0.43 μM. Density functional theory (DFT) studies revealed that the doped Mo atom exhibited a higher d-band center compared to the Co atom. A stronger p-d orbital hybridization between the glucose and the Mo atoms indicated the enhancement of glucose adsorption and activation. Importantly, Mo-CoO-1 provided a good selectivity and long-term stability, which can be expected to be used in future practical applications.

Enhanced CO oxidation performance over hierarchical flower-like Co3O4 based nanosheets via optimizing oxygen activation and CO chemisorption

Enhancing low-temperature activity is a focus for carbon monoxide (CO) elimination by catalytic oxidation. In this work, the hierarchical flower-like silver (Ag) modified cobalt oxides (Co3O4) nanosheets were prepared by solvothermal method and applied into catalytic CO oxidation. The doped Ag species in the form of AgCoO2 induced the prolongated surface Co-O bond and weaker bond intensity. Consequently, the oxygen activation/migration ability and redox capacity of Ag0.02Co were enhanced with more oxygen vacancies. The chemisorbed CO was preferentially converted to CO2 but not carbonates. The inhibited carbonates accumulation could avoid the coverage of active sites. According to Density functional theory (DFT) calculations, the electron transfer from AgCoO2 to Co3O4 promote electron donation ability of Co3O4 layer, benefiting for oxygen activation. Moreover, the longer Co-C and C-O bond length suggest the weakened chemisorption strength and higher active of CO molecule. The Ag modified Co3O4 exhibited more satisfactory activity at lower temperature. Typically, it realized 100% CO conversion at 90 °C, and displayed 6.3-fold higher reaction rate than pristine Co3O4 at 40 °C. Moreover, the Ag0.02Co exhibited outstanding long-term stability and water resistance. In summary, the optimized oxygen activation, CO chemisorption and interfacial electron transfer synergistically boosted the CO oxidation activity on Ag modified Co3O4.

Synthesis of cordierite using municipal solid waste incineration fly ash as one additive for enhanced catalytic oxidation of volatile organic compounds

Municipal solid waste incineration (MSWI) fly ash is a hazardous waste, which needs various recycling in order to reach "net-zero waste". This work aimed to synthesize cordierite using MSWI fly ash as one additive and investigate influence of the additive on properties of the cordierite. As a result, the cordierite was successfully synthesized when the additive weight ratio was <15 % and the synthesis strategy was universally feasible for 14 kinds of different MSWI fly ashes. As a heat accumulator, the cordierite attained compressive strength of 42.1 MPa, water absorption of 26 %, bulk density of 1.87 g·cm-3, and open porosity of 47 %. After five cycles of thermal impact at 1200 °C, the strength was only decreased by 15 %. These properties were comparable to a commercial cordierite. As a catalyst carrier, after loading Mn and Cu species, the cordierite removed 100 % of toluene at 250 °C. In comparison, a commercial cordierite only got a removal of 34.4 %. The enhanced activity was attributed to co-existing spinel and bytownite as well as imbedded Zn and Cu in the MSWI fly ash-added cordierite. Therefore, this work devotes to hazardous recycling, green development, and cycled economy.

Redox-Induced In Situ Growth of MnO2 with Rich Oxygen Vacancies over Monolithic Copper Foam for Boosting Toluene Combustion

Catalytic combustion has been known to be an effective technique in volatile organic compound (VOC) abatement. Developing monolithic catalysts with high activity at low temperatures is vital yet challenging in industrial applications. Herein, monolithic MnO₂-O_v/CF catalysts were fabricated via the in situ growth of K₂CuFe(CN)₆ (CuFePBA, a family of metal-organic frames) over copper foam (CF) followed by a redox-etching route. The as-synthesized monolith MnO₂-O_v-0.04/CF catalyst displays a superior low-temperature activity (T_90% = 215 °C) and robust durability for toluene elimination even in the presence of 5 vol % water. Experimental results reveal that the CuFePBA template not only guides the in situ growth of δ-MnO₂ with high loading over CF but also acts as a source of dopant to create more oxygen vacancies and weaken the strength of the Mn-O bond, which considerably improves the oxygen activation ability of δ-MnO₂ and consequently boosts the low-temperature catalytic activity of the monolith MnO₂-O_v-0.04/CF toward toluene oxidation. In addition, the reaction intermediate and proposed mechanism in the MnO₂-O_v-0.04/CF mediated catalytic oxidation process were investigated. This study provides new insights into the development of highly active monolithic catalysts for the low-temperature oxidation of VOCs.

In situ growth of the CoO nanoneedle array on a 3D nickel foam toward a high-performance glucose sensor

A glucose sensor with high sensitivity and low detection limit is vital for human beings' health. Herein, a CoO nanoneedle array with an unique electronic structure was successfully constructed by a hydrothermal and subsequent high-temperature calcination process. The optimized CoO-400 nanoneedles exhibit a larger electrochemical active surface area, beneficial electronic structure, favorable lattice distortion, and abundant active sites, which effectively promote electrochemical properties toward glucose sensing. The glucose sensor constructed by CoO-400 nanoneedles shows a high sensitivity of 84.23 mA cm^-2 mM^-1 and low detection limit of 4.4 × 10^-7 M, superior to the results from most previous reports. Moreover, outstanding anti-interference ability, superior long-term stability, good repeatability, and satisfactory reproducibility in glucose detection for CoO-400 nanoneedles are also demonstrated.

Effective Toluene Ozonation over δ-MnO2: Oxygen Vacancy-Induced Reactive Oxygen Species

To improve the reactivity and lifetime of catalysts in the catalytic ozonation of toluene, a simple strategy was provided to regulate the morphology and microstructure of δ-MnO₂ via the hydrothermal reaction temperature. The effects of the reaction temperature and the ozone to toluene concentration ratio on the catalyst performance were investigated. The optimized MnO₂-260 catalyst prepared at the limiting hydrothermal temperature (260 °C) showed high catalytic activity (X_Tol = 95%) and excellent stability (1200 min) at the approximately ambient temperature of 40 °C, which was superior to the results in previous studies. The structure and morphology of δ-MnO₂ were characterized by extended X-ray absorption fine structure, X-ray diffraction, scanning electron microscopy, positron annihilation lifetime spectroscopy, electron spin resonance, and other techniques. Experimental results and density functional theory calculations were in agreement that surface oxygen vacancy clusters, especially surface oxygen dimer vacancies, are critical in ozone activation. Oxygen vacancies can facilitate the adsorption and activation of O₃ to generate reactive oxygen species (ROS, including ¹O₂, O₂^-, and ^•OH), leading to superior ozonation activity to degrade toluene and intermediates. Meanwhile, free radical detection and scavenger tests indicated that ^•OH is the primary ROS during toluene ozonation rather than ¹O₂ or O₂^-.

Insights into the influence of water molecules on selective catalytic ozonation of gaseous ammonia into nitrogen on cryptomelane-type manganese oxide using in-situ DRIFTS

Catalytic ozonation is an environmentally friendly technology for the removal of gaseous NH₃ due to high NH₃ conversion and high N₂ selectivity at ambient temperature. However, the influence mechanism of ubiquitous water vapor on catalytic ozonation of NH₃ is unclear. In this study, cryptomelane-type manganese oxide (OMS-2) catalyst was prepared and tested for catalytic ozonation of NH₃ in different relative humidity. The results showed that water vapor significantly decreased the catalytic activity, which was due to the inhibition of water on NH₃ adsorption on Lewis acid sites and O₃ decomposition on oxygen vacancies, as well as the combination of water with active oxygen species (O₂^2- and O_atom). And the effect of water vapor on NH₃ conversion was more significant than O₃ decomposition because more Mn-OH were involved in the O₃ decomposition under humid conditions. Combining in-situ DRIFTS results with the performance of NH₃ oxidation, it is found that L-2 acid sites (the peak of NH₃ adsorption on Lewis acid sites at 1188 cm^-1) were the main active sites for adsorption and activation of NH₃ in the early stage of catalytic reaction; as the reaction progressed, L-2 acid sites were gradually occupied by water and more Brønsted acid sites participated in the catalytic reaction. This work deepened the understanding of the reaction process for selective catalytic ozonation of NH₃, and provided theoretical guidance for the design of efficient hydrophobic catalysts to eliminate gaseous NH₃ pollution.

In Situ Fabrication of Highly Dispersed Co-Fe-Doped-δ-MnO2 Catalyst by a Facile Redox-Driving MOFs-Derived Method for Low-Temperature Oxidation of Toluene

Cost-efficient and durable manganese-based catalysts are in great demand for the catalytic elimination of volatile organic compounds (VOCs), which are dominated not only by the nanostructures but also by the oxygen vacancies and Mn-O bond in the catalysts. Herein, a series of nanostructured Co-Fe-doped-δ-MnO₂ catalysts (Co-Fe-δ-MnO₂) with high dispersion were in situ fabricated by employing metal-organic-frameworks (MOFs) as reducing agents, dopants, and templates all at the same time. The as-obtained Co-Fe-δ-MnO₂-20% catalyst exhibited robust durability and high catalytic activity (225 °C) for toluene combustion even in the presence of 5 vol % water vapor, which is 50 °C lower than that of pristine δ-MnO₂. Various characterizations revealed that the homogeneously dispersed codoping of Co and Fe ions into δ-MnO₂ promotes the generation of oxygen vacancies and weakens the strength of the Mn-O bond, thus increasing the amount of adsorbed oxygen (O_ads) and improving the mobility of lattice oxygen (O_latt). Meanwhile, due to successfully inheriting the framework structures of MOFs, the obtained catalyst exhibited a high surface area and three-dimensional mesoporous structure, which contributes to diffusion and increases the number of active sites. Moreover, in situ DRIFTS results confirmed that the toluene degradation mechanism on the Co-Fe-δ-MnO₂-20% follows the MVK mechanism and revealed that more O_ads and high-mobility O_latt induced by this novel method contribute to accumulating and mineralizing key intermediates (benzoate) and thus promote toluene oxidation. In conclusion, this work stimulates the opportunities to develop Co-Fe-δ-MnO₂ as a class of nonprecious-metal-based catalysts for controlling VOC emissions.

Promoting the Catalytic Ozonation of Toluene by Introducing SO42- into the α-MnO2/ZSM-5 Catalyst to Tune Both Oxygen Vacancies and Acid Sites

Mn-based catalysts hold the promise of practical applications in catalytic ozonation of toluene at room temperature, yet improvement of toluene conversion and CO_x selectivity remains challenging. Here, an innovative α-MnO₂/ZSM-5 catalyst modified with SO₄^2- was successfully prepared, and both characterizations and density functional theory (DFT) calculations showed that SO₄^2- introduction facilitated the formation of oxygen vacancies, Lewis and Brönsted acid sites, and active oxygen species and enhanced the adsorption ability of toluene on α-MnO₂/ZSM-5. Characterizations also showed that SO₄^2- introduction made the catalyst possess larger specific surface area, superior reducibility, and stronger surface acidity. As a result, α-MnO₂/ZSM-5 with a S/Mn molar ratio of 0.019 exhibited the best toluene conversion and CO_x selectivity, 87 and 94%, respectively, after the reaction for 8 h at 30 °C under an initial concentration of 5 ppm toluene and 45 ppm ozone, relative humidity of 45%, and space velocity of 32,000 h^-1, far superior to those of non-noble catalysts reported to date under comparable reaction conditions. The synergistic role of increased oxygen vacancies and acid sites of α-MnO₂/ZSM-5 modified with SO₄^2- resulted in excellent toluene conversion and CO_x selectivity. The findings represented a critical step toward the rational design and synthesis of highly efficient catalysts for catalytic ozonation of toluene.

Enhanced water-resistance of Mn-based catalysts for ambient temperature ozone elimination: Roles of N and Pd modification

Cryptomelane-type MnO₂ catalysts own excellent ozone (O₃) decomposition performance. However, it is urgent to improve their long-term stability at ambient temperature, especially under the presence of water. In the present study, a modification strategy was proposed by N-doping and the successive Pd introduction. The N-doping of MnO₂ by NH₄Cl (NH₄-MnO₂) can increase its activity for O₃ decomposition. And almost 100% O₃ decomposition was achieved within 24 h under water-free atmosphere at ambient temperature (25 °C). Successive Pd addition further promoted the water-resistance of NH₄-MnO₂ catalyst under high humidity (RH > 90%). In combination with detailed characterizations, it indicated that the enhancements on stability and water-resistance were attributed to synergistic effect among acid sites, oxygen defects and Pd clusters. Finally, the decomposition mechanism of gaseous O₃ was proposed based on three decisive active sites above.

Low-Temperature Combustion of Toluene over Cu-Doped SmMn2O5 Mullite Catalysts via Creating Highly Active Cu2+-O-Mn4+ Sites

Catalytic combustion of volatile organic compounds (VOCs) at low temperatures is still an urgent issue to be solved. Herein, low-temperature combustion of toluene over Cu-doped SmMn₂O₅ mullite catalysts via creating highly active Cu²⁺-O-Mn⁴⁺ sites has been originally demonstrated. Cu-doped SmMn₂O₅ mullite catalysts exhibited 90% conversion of toluene at 206 °C and displayed robust stability even in the presence of water. It has been demonstrated that Cu doping created Cu²⁺-O-Mn⁴⁺ active composite sites that were more exposed after removing surface Sm species via acid-etching. Benefiting from this, the redox and oxygen activation ability of catalysts was significantly enhanced. The consumption of benzaldehyde and benzoic acid as intermediate species and the CO₂ generation ability were apparently promoted, which were the direct reasons for the enhanced low-temperature combustion of toluene. This work provides novel ideas for the development of high-performance catalysts for low-temperature VOC combustion, which has great industrial application prospects.

Ozone Decomposition below Room Temperature Using Mn-based Mullite YMn2O5

A super-low-temperature ozone decomposition is realized without energy consumption on a ternary oxide catalyst mullite YMn₂O₅ for the first time. The YMn₂O₅ oxide catalyzed ozone decomposition from a low temperature of -40 °C with 29% conversion (reaction rate: 1534.2 μmol g^-1 h^-1) and quickly reached 100% (5459.5 μmol g^-1 h^-1) when warmed up to -5 °C. The superior low-temperature performance over YMn₂O₅ could surpass that of the reported ozone decomposition catalysts. The structure and element valence characterizations confirmed that YMn₂O₅ remained the same after 100 h of room-temperature reaction, indicating excellent durability of the catalyst. O₂-TPD (O₂-temperature-programmed desorption) showed that the active sites are the Mn³⁺ sites bonded with singly coordinated oxygen on the surface. Combined with in situ Raman measurements and density functional theory calculations, we found that the ozone decomposition reaction on YMn₂O₅ showed a barrier of only 0.29 eV, following the Eley-Rideal (E-R) mechanism with a rate-limiting step of intermediate O₂^2- desorption. The low barrier minimizes the accumulation of intermediate products and realizes the fast O₃ decomposition even at super-low temperatures. Fundamentally, the moderate Mn-O bonding strength in the low-symmetry ternary oxides is crucial to produce singly coordinated active species on the surface responsible for the efficient ozone degradation at low temperatures.

Construction of K and Tb Co-doped MnO2 nanoparticles for enhanced oxidation and detoxication of organic dye waste

Developing low-cost and efficient materials for dye pollutant removal under mild condition remains a great challenge. Here K⁺ and Tb³⁺ co-doped porous MnO₂ (K-Tb-MnO₂) nanoparticles with tailored properties including crystal structure, surface area and catalytic activity have been synthesized. Experimental results reveal that K-Tb-MnO₂ nanoparticle has higher specific surface area, Mn³⁺ content and surface oxygen vacancies than pristine MnO₂ nanoparticle and single-doped MnO₂ materials, showing the uniqueness of dual-doped metal ions. Using methyl blue (MB) as a model pollutant, its removal efficiency by K-Tb-MnO₂ nanoparticles within 5 min is 93.6%, which is 18, 8.3, and 2.9 times higher than that of MnO₂, K-MnO₂, and Tb-MnO₂ nanomaterials, respectively. Oxalic acid triggered MnO₂ material dissolving assay and FT-IR spectrum suggested that remarkable performance of K-Tb-MnO₂ nanoparticle toward MB removal can be attributed to a combined effect of adsorption (16% MB removal) and catalytic degradation (84% MB removal). Moreover, K-Tb-MnO₂ nanoparticle mediated MB degradation is demonstrated to be a combination of non-radical oxidation by Mn³⁺ and radical-participated degradation, with ¹O₂ as the main species. And the intermediates and pathways of MB degradation were studied by liquid chromatography-mass spectrometry. Importantly, cell viability experiment suggests that the toxicity of MB dye could be efficiently alleviated after the treatment with K-Tb-MnO₂ nanoparticle. These results demonstrate the great potential of the novel K-Tb-MnO₂ particles to be used as a highly effective nanomaterials to reduce the risk of dye wastes toward the environment and human health.

Noble Metal Single-Atom Catalysts for the Catalytic Oxidation of Volatile Organic Compounds

Volatile organic compounds (VOCs) are detrimental to the environment and human health and must be eliminated before discharging. Oxidation by heterogeneous catalysts is one of the most promising approaches for the VOCs abatement. Precious metal catalysts are highly active for the catalytic oxidation of VOCs, but they are rare and their high price limits large-scale application. Supported metal single-atom catalysts (SACs) have a high atom efficiency and provide the possibility to circumvent such limitations. This Review summarizes recent advances in the use of metal SACs for the complete oxidation of VOCs, such as benzene, toluene, formaldehyde, and methanol, as well as aliphatic and Cl- and S-containing hydrocarbons. The structures of the metal SACs used and the reaction mechanisms of the VOC oxidation are discussed. The most widely used SACs are noble metals supported on oxides, especially on reducible oxides, such as Mn₂ O₃ and TiO₂ . The reactivity of most SACs is related to the activity of surface lattice oxygen of the oxides. Furthermore, several metal SACs show better reactivity and improved S and Cl resistance than the corresponding nanocatalysts, indicating that SACs have potential for application in the oxidation of VOCs. The deactivation and regeneration mechanisms of the metal SACs are also summarized. It is concluded that the application of metal SACs in catalytic oxidation of VOCs is still in its infancy. This Review aims to elucidate structure-performance relationships and to guide the design of highly efficient metal SACs for the catalytic oxidation of VOCs.

Activation and characterization of environmental catalysts in plasma-catalysis: Status and challenges

Plasma-catalysis has attracted great attentions in environmental/energy-related fields, but the synergetic mechanism still suffers intractable defects. Key issues are that what kind of catalysts are applicable for plasma system, how are they activated in plasma, and how to characterize them in plasma. This review systematically gives a comprehensive summarization of the selection of catalysts and its activation mechanism in plasma, based on the character of plasma, including physical effects containing the enhancement of discharge intensity and adsorption of reactants, and the utilization of plasma-generated active species such as·O, heat, O₃, ultraviolet light and e* . Focus is given to the illumination of the activation mechanisms of catalysts when placed in plasma zone. Subsequently, the novel characterization techniques for catalysts, which may associate properties to performance, are critically overviewed. The challenges and opportunities for the activation and characterizations of catalysts are proposed, and future perspectives are suggested about where the efforts should be made. It is expected that a bridge between catalysts design and character of plasma can be built to shed light on the synergetic mechanism for plasma-catalysis and design of new plasma-catalysis systems.

Boosting Toluene Combustion by Tuning Electronic Metal-Support Interactions in In Situ Grown Pt@Co3O4 Catalysts

Electronic metal-support interaction (EMSI) has attracted great attention in volatile organic compound (VOC) abatement. Herein, Pt@Co₃O₄ catalysts were prepared via a metal-organic framework (MOF) in situ growth approach to boost toluene degradation. The partial electron transfer from Co₃O₄ to Pt species was induced by the EMSI effect to generate the electron-rich Pt and Co³⁺ species. The electrophilic O₂ molecules could be activated by picking up the electrons from electron-rich Pt species to form nucleophilic oxygen species, which is conducive to attack C-H bonds in toluene. The redox ability and surface oxygen species activity of catalysts were improved due to strong EMSI. As expected, the excellent toluene activity was achieved, meanwhile exhibiting satisfactory water resistance and long-term stability for toluene combustion. In situ diffuse reflectance infrared Fourier transform spectroscopy results elucidated that surface lattice oxygen species should deeply participate in toluene degradation, which could be efficiently replenished by gaseous oxygen. This work may provide a new idea for exploring the relationship between the electron transfer effect and efficient catalytic performance of VOCs.

Atomically dispersed Ag on δ-MnO2via cation vacancy trapping for toluene catalytic oxidation

Atomic dispersion of Ag on δ-MnO2 was achieved via H2O2-induced Mn vacancy trapping. Single-atom Ag could activate adjacent lattice oxygen, facilitating methyl oxidation and benzene ring cleavage to improve toluene oxidation activity.

Core-Shell-Like Structured Co3O4@SiO2 Catalyst for Highly Efficient Catalytic Elimination of Ozone

Co₃O₄ is an environmental catalyst that can effectively decompose ozone, but is strongly affected by water vapor. In this study, Co₃O₄@SiO₂ catalysts with a core-shell-like structure were synthesized following the hydrothermal method. At 60% relative humidity and a space velocity of 720,000 h⁻¹, the prepared Co₃O₄@SiO₂ obtained 95% ozone decomposition for 40 ppm ozone after 6 h, which far outperformed that of the 25wt% Co₃O₄/SiO₂ catalysts. The superiority of Co₃O₄@SiO₂ is ascribed to its core@shell structure, in which Co₃O₄ is wrapped inside the SiO₂ shell structure to avoid air exposure. This research provides important guidance for the high humidity resistance of catalysts for ozone decomposition.

Boosting the Dispersity of Metallic Ag Nanoparticles and Ozone Decomposition Performance of Ag-Mn Catalysts via Manganese Vacancy-Dependent Metal-Support Interactions

Ozone (O₃) removal has important implications for environmental protection and human health, and Ag-Mn catalysts have shown promising O₃ decomposition. Catalysts with Ag supported on porous cube-like α-Mn₂O₃ (Ag/Mn-C) with high utilization of Ag were prepared by the impregnation method and showed excellent O₃ decomposition activity. Physicochemical characterizations demonstrated that metallic Ag nanoparticles (Ag_n⁰) were mainly anchored on manganese vacancies, forming Ag-O-Mn bonds between Ag_n⁰ and α-Mn₂O₃-C. The abundant manganese vacancies of α-Mn₂O₃-C can lead to Ag_n⁰ with a smaller particle size and more uniform dispersion, thereby resulting in markedly enhanced O₃ decomposition performance compared to Ag_n⁰ with a large particle size and uneven distribution on rod-like α-Mn₂O₃ (Ag/Mn-R). Under a relative humidity of 65% and a space velocity of 1,110,000 h^-1, the conversion of 40 ppm O₃ over the 2%Ag/Mn-C catalyst within 6 h (98%) at 30 °C was more than twice as high as that of the 2%Ag/Mn-R catalyst (42%). The study provides guidance for the design of highly efficient Ag-based catalysts and the understanding of the microstructure of supported catalysts.

A novel γ-like MnO2 catalyst for ozone decomposition in high humidity conditions

MnO₂ catalysts have been widely studied for catalytic gaseous ozone decomposition. However, their poor moisture resistance often leads to undesirable catalytic effects in the presence of high humidity. In this study, a novel catalyst with γ-like MnO₂ was synthesized using the selective dissolution method on LaMnO₃ perovskites. The as-prepared catalyst exhibited quite stable ozone conversion of ~90% within 12 h under 75% relative humidity (400-800 ppm of ozone, 30 °C, 150 000 mL·g^-1·h^-1 of WHSV). In contrast, traditional γ-MnO₂ catalyst showed deficient resistance to H₂O and sensitivity to space velocity. Detailed characterizations showed that the larger number of oxygen vacancies induced by structure reconstruction of the γ-like MnO₂ and residual La³⁺ cations facilitated ozone decomposition in humid atmosphere. Finally, the reaction rate of ozone decomposition was proposed by a kinetic study, which further proved that the amount and hydrophilicity of oxygen vacancies are the determinants of the first-order reaction rate constant.

Terminal Hydroxyl Groups on Al2O3 Supports Influence the Valence State and Dispersity of Ag Nanoparticles: Implications for Ozone Decomposition

Ozone is a poisonous gas, so it is necessary to remove excessive ozone in the environment. Catalytic decomposition is an effective way to remove ozone at room temperature. In this work, 10%Ag/nano-Al₂O₃ and 10%Ag/AlOOH-900 catalysts were synthesized by the impregnation method. The 10%Ag/nano-Al₂O₃ catalyst showed 89% ozone conversion for 40 ppm O₃ for 6 h under a space velocity of 840 000 h^-1 and a relative humidity of 65%, which is superior to 10%Ag/AlOOH-900 (45% conversion). The characterization results showed Ag nanoparticles to be the active sites for ozone decomposition, which were more highly dispersed on nano-Al₂O₃ as a result of the greater density of terminal hydroxyl groups. The understanding of the dispersion and valence of silver species gained in this study will be beneficial to the design of more efficient supported silver catalysts for ozone decomposition in the future.

Recent Progress of Thermocatalytic and Photo/Thermocatalytic Oxidation for VOCs Purification over Manganese-based Oxide Catalysts

Volatile organic compounds (VOCs) are one of the main sources of air pollution, which are of wide concern because of their toxicity and serious threat to the environment and human health. Catalytic oxidation has been proven to be a promising and effective technology for VOCs abatement in the presence of heat or light. As environmentally friendly and low-cost materials, manganese-based oxides are the most competitive and promising candidates for the catalytic degradation of VOCs in thermocatalysis or photo/thermocatalysis. This article summarizes the research and development on various manganese-based oxide catalysts, with emphasis on their thermocatalytic and photo/thermocatalytic purification of VOCs in recent years in detail. Single manganese oxides, manganese-based oxide composites, as well as improving strategies such as morphology regulation, heterojunction engineering, and surface decoration by metal doping or universal acid treatment are reviewed. Besides, manganese-based monoliths for practical VOCs abatementare also discussed. Meanwhile, relevant catalytic mechanisms are also summarized. Finally, the existing problems and prospect of manganese-based oxide catalysts for catalyzing combustion of VOCs are proposed.

Boosting benzene combustion by engineering oxygen vacancy-mediated Ag/CeO2-Co3O4 catalyst via interfacial electron transfer

Oxygen vacancy (O_v) engineering is a widely accepted effective strategy to manipulate the catalytic activity for volatile organic compounds (VOCs) abatement. Herein, we report the oxygen vacancy-mediated Ag/CeO₂-Co₃O₄ catalyst to boost benzene combustion. The incorporation of Ag species in Ag/CeO₂-Co₃O₄ induces the predominately exposed surface Co³⁺ sites and structural distortion of Co₃O₄ as well as rich oxygen vacancy owing to the improved interfacial electron transfer, which promote the adsorption of benzene and the dissociation of oxygen. The low-temperature reducibility and mobility of oxygen species are also improved due to the generation of oxygen vacancy. The isotopic ¹⁸O₂ exchange experiments demonstrate that abundant oxygen vacancies contribute to the rapid generation of active oxygen species, and the consumed oxygen vacancies can be compensated steadily during benzene oxidation. In-situ DRIFTS results reveal that benzene oxidation is a continuous oxidation process, and active oxygen species plays a crucial role in the deep oxidation of benzene by engineering oxygen vacancy. This work provides an efficient strategy for designing high-performance environmental catalysts for VOCs abatement.

Synergistic multiple active species driven fast estrone oxidation by δ-MnO2 in the existence of methanol

Endocrine-disrupting chemicals (EDCs) cause serious threats to human health. Five types of MnO₂ were synthesized and characterized. They exhibited different removal performances for three EDCs, i.e., estrone (E1), ethynylestradiol (EE2) and bisphenol A (BPA). Only δ-MnO₂ can completely remove E1 within 120 min at pH 3.0. Free Mn (III) was determined at the beginning of the reaction and participated in the EDCs removal process. Electron spin resonance (ESR) indicated that δ-MnO₂ could produce superoxide anions (·O₂^-) and singlet oxygen (¹O₂) in the existence of methanol. The reactive oxygen species (ROS) quenching experiments showed ¹O₂ have certain contribution to the E1 removal by δ-MnO₂. The source of ROS is mainly the lattice oxygen from δ-MnO₂, and can be replenished through the layer structure destruction caused by the reaction between Mn(III) and E1. The ROS dependent EDCs removal by δ-MnO₂ leads to a deep understanding on this well-known oxidant.

Comparative Investigation on Chlorobenzene Oxidation by Oxygen and Ozone over a MnOx/Al2O3 Catalyst in the Presence of SO2

Catalytic oxidation of volatile organic compounds (VOCs) usually encounters complicated components in flue gas causing severe deactivation that restrict its application in specific conditions. The Cl substitution in chlorobenzene further increases poisoning risks. Ozone assistance has unique superiority that can overcome these bottleneck problems. Herein, this study performs a comparative investigation of CB oxidation by oxygen and ozone over a simple Mn/Al₂O₃ catalyst. CB conversion suffered from slight deactivation in oxygen atmosphere (from 90 to 70%) and more severe deactivation in the presence of SO₂ (from 90 to 45%) at 480 °C. Introduction of ozone successfully attained high CB conversion at low temperature (120 °C) with excellent stability and less byproducts. Especially, CB oxidation by ozone maintained its original conversion in the presence of SO₂. The deactivation process was simulated by synthesizing several sulfated catalysts. Direct sulfation on Mn/Al₂O₃ attained more severe deactivation in CB conversion and CO₂ formation than sulfation on the Al₂O₃ support. Ozone with a strong oxidation property promoted the CB oxidation cycle, facilitated desorption of carbonaceous intermediates, and protected MnO_x species from severe erosion, thus exhibiting high and stable performance in CB oxidation.

MnO2 -Based Materials for Environmental Applications

Manganese dioxide (MnO₂ ) is a promising photo-thermo-electric-responsive semiconductor material for environmental applications, owing to its various favorable properties. However, the unsatisfactory environmental purification efficiency of this material has limited its further applications. Fortunately, in the last few years, significant efforts have been undertaken for improving the environmental purification efficiency of this material and understanding its underlying mechanism. Here, the aim is to summarize the recent experimental and computational research progress in the modification of MnO₂ single species by morphology control, structure construction, facet engineering, and element doping. Moreover, the design and fabrication of MnO₂ -based composites via the construction of homojunctions and MnO₂ /semiconductor/conductor binary/ternary heterojunctions is discussed. Their applications in environmental purification systems, either as an adsorbent material for removing heavy metals, dyes, and microwave (MW) pollution, or as a thermal catalyst, photocatalyst, and electrocatalyst for the degradation of pollutants (water and gas, organic and inorganic) are also highlighted. Finally, the research gaps are summarized and a perspective on the challenges and the direction of future research in nanostructured MnO₂ -based materials in the field of environmental applications is presented. Therefore, basic guidance for rational design and fabrication of high-efficiency MnO₂ -based materials for comprehensive environmental applications is provided.

Surface In Situ Doping Modification over Mn2O3 for Toluene and Propene Catalytic Oxidation: The Effect of Isolated Cuδ+ Insertion into the Mezzanine of Surface MnO2 Cladding

Heterocation insertion and substitution in tunnels and mezzanines of MnO₂ present significant influences on the microchemical environment at the surfaces and interfaces. An innovative surface in situ doping modification method via Cu²⁺-H⁺/KMnO₄ treatment was applied onto the Mn₂O₃ surface to provide Mn₂O₃@MnO₂ nanospheres. Cu was stabilized into resulting MnO₂ cladding substituting original K⁺ during a mild comproportionation reaction between Mn(VII) and Mn(III). The Cu25 (Cu(II): Mn(VII)_atomic = 25%) catalyst shows significant promotion of the catalytic performance compared with bare Mn₂O₃ and Cu0 (without Cu involving). Isolated Cu^δ+ was predominantly inserted into the mezzanine of the [MnO₆]^δ- layers in MnO₂ instead of K⁺, leading to slight electron transfer from Cu^δ+ to outermost Mn^(4-ε)+ and a decrease of interlayer spacing as well as crystallinity. Such a configuration facilitates the formation of additional oxygen vacancies, promoting the redox ability and oxygen mobility at relatively low temperatures. The mechanistic study reveals that Cu^δ+ in MnO₂ cladding boosts the activation of toluene (methyl) to form benzoates and propene (methyl and double bonds) to form carboxylates, enhancing the chemical adsorption of reactants. Moreover, it also inhibits the unfavored accumulation of incomplete oxidized intermediates on the surface at high temperatures.

Synergistic Effects of Multicomponents Produce Outstanding Soot Oxidation Activity in a Cs/Co/MnOx Catalyst

The control of soot emission from diesel vehicles is of extraordinary importance to the environment, and catalytic removal of soot is a highly effective and clean method. Here, we report a novel, non-noble metal catalyst for application in the catalytic combustion of soot with superb activity and resistance to H₂O and SO₂. MnO_x oxide was prepared via a hydrothermal method, and then, Cs and Co were loaded on MnO_x by impregnation. The 5%Cs/1%Co/MnO_x catalyst displayed excellent catalytic activity with values of T₁₀ (332 °C), T₅₀ (371 °C), and T₉₀ (415 °C) under loose contact. The as-prepared catalysts were investigated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), H₂ temperature-programmed reduction (TPR), O₂ temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure (XAFS). The results suggest that, after the introduction of Cs and Co into the MnO_x oxide, more NO₂ molecules take part in soot oxidation, exhibiting higher NO₂ utilization efficiency; this is due to the synergistic effects of multiple components (Cs, Co, and Mn) promoting the generation of more surface-active oxygen and then accelerating the reaction between NO₂ and soot. This study provides significant insights into the development of high-efficiency catalysts for soot oxidation, and the developed 5%Cs/1%Co/MnO_x catalyst is a promising candidate for application in diesel particulate filters.

Exploring an efficient manganese oxide catalyst for ozone decomposition and its deactivation induced by water vapor

A series of MnO_x catalysts supported by carbon spheres were prepared by calcining mixtures of manganese acetate and carbon spheres under a nitrogen atmosphere, and their performance for ozone decomposition under high humidity conditions (RH = 90%) was evaluated.