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.

Introduction

Ozone is widely used in food, medicine, and waste treatment owing to its excellent oxidizing ability (Alameddine et al., 2021; Kim et al., 2022). However, even low concentrations of ozone are harmful to human health, especially to the eyes, nose, and throat (Ferrara et al., 2020; Ferrara et al., 2021). The maximum eight-hour average concentration of ozone allowed by the World Health Organization is 100 μg/m³. Ozone concentrations in the atmosphere near ground level have considerably increased in recent years due to increased levels of volatile organic compounds and nitrogen oxides (Ou et al., 2016). Ozone in the outdoor air can infiltrate into indoor environments. Indoor ozone is considered more harmful than outdoor ozone because modern humans spend most of their time indoors (Abbass et al., 2017; Namdari et al., 2021; Nazaroff and Weschler 2021). The development of environmental technologies to effectively eliminate ozone is therefore necessary.

There are four common treatment methods to eliminate ozone: activated carbon (Yu et al., 2020); absorption (Yang et al., 2017); thermal decomposition and catalytic decomposition (Gopi et al., 2017; Ma et al., 2017; Gong et al., 2018). Catalytic decomposition is considered to be one of the most feasible and effective methods for ozone removal (Li et al., 2020). Noble metals and transitional metal oxides are common catalysts for heterogeneous reactions including decomposition of ozone (Nikolov et al., 2010; Gong et al., 2017; Deng et al., 2019; Tao et al., 2021a; Tao et al., 2021b). Among the transition metal oxides, Co_xO_y catalysts with higher oxidation states have exhibited higher ozone decomposition performance than other cobalt oxide catalysts (Tang et al., 2014a). Abdedayem (Abdedayem et al., 2017) demonstrated that the ozone decomposition abilities of Co₃O₄ support on loaded olivine is proportional to its dispersion degree. However, numerous metal oxide catalysts suffer from interactions with water vapor, and including cobalt oxides (Zhu et al., 2021). It is generally believed that water vapor affects ozone decomposition via competitive adsorption with the transition metal oxides on the active sites (Jia et al., 2016).

In this study, core@shell structure catalysts were synthesized with mesoporous silica as the shell and Co₃O₄ nanoparticles as the core (Co₃O₄@SiO₂) following the solvothermal route using polyvinylpyrrolidone (PVP) as the capping agent. For comparison, spherical silica supported different additions of Co₃O₄ and labeled xCo₃O₄/SiO₂, where x = 10, 15, and 20, or 25%. The ozone decomposition performance of xCo₃O₄/SiO₂ increased with increasing Co₃O₄. The 25Co₃O₄/SiO₂ and Co₃O₄@SiO₂ catalysts yielded high ozone decomposition activity at 20% relative humidity. The ozone elimination activity of 20Co₃O₄/SiO₂ sharply decreased upon increasing the relative humidity to 60%, and the Co₃O₄@SiO₂ catalyst exhibited a better moisture resistance performance for ozone decomposition. This study provides important insights for the further development of coated catalysts for gaseous ozone decomposition.

Experimental Methods

Catalyst Preparation

Co₃O₄@SiO₂ was synthesized in accordance with previously published studies (Khan et al., 2015). First, 0.70 g PVP and 0.35 g Co(NO₃)₂·6H₂O were dissolved in 40 ml ethanol. The solutions were transferred to stainless steel lined with Poly tetra fluoroethylene (PTFE) in an autoclave and heated at 453 K for 4 h. The obtained black powder was dispersed in 103.8 ml ethanol, to which 82.8 ml distilled water, 7.2 ml 25% aqueous ammonia solution, 0.3 g cetyltrimethylammonium bromide, and 1.0 ml tetraethoxysilane were added. The solution was stirred for 48 h at room temperature. The product was collected via filtration, washed three times with distilled water, dried at 333 K, and then calcined at 773 K for 6 h. The finished samples were denoted as Co₃O₄@SiO₂ (wt% = 30%). SiO₂ was impregnated with 10, 15, 20, or 25% cobalt loading in an ethanol solution of cobalt nitrate, and the resulting product was calcined at 773 K for 6 h. The prepared samples were labeled as 10Co₃O₄/SiO₂, 15Co₃O₄/SiO₂, 20Co₃O₄/SiO₂, and 25Co₃O₄/SiO₂, respectively.

Catalyst Characterization

The samples were characterized by X-ray diffraction (XRD) using a D/max-RB diffractometer. X-ray photoelectron spectroscopy (XPS) was performed using a Thermo Fisher ESCALAB 250Xi. Morphological and microstructural characterizations were carried out using a Hitachi EM-3010 transmission electron microscope (TEM). The surface areas were calculated by the Brunauer-Emmett-Teller (BET) method. The pore diameters were estimated from the desorption branchers of the isotherms based on the Barrett-Joyner-Halenda (BJH) model.

Catalyst Test

The ozone decomposition activity of the prepared catalysts was evaluated using a flow-through quartz tube reactor (inner diameter = 10 mm) with 0.10 g of catalyst separated by quartz sand at different temperatures and relative humidity (20, 40, and 60%) under atmospheric pressure conditions. Ozone was generated by flowing 20% O₂/N₂ compressed gas through an ozone generator. The relative humidity of the gas stream was measured using a humidity probe (Benetech, GM1361+). The total gas flow rate passing through the quartz reactor was controlled at 1,500 ml/min and contained 40 ppm O₃. The ozone concentrations at the inlet and outlet were detected using a 106-L ozone online analyzer (2B Technologies, Boulder, Co, United States). The ozone conversion was calculated according to:

$\text{Ozone conversion}=\frac{C_i\left(O_3\right)-C_o\left(O_3\right)}{C_i\left(O_3\right)}\times 100\text{\%}$

where $c_i\left(O_3\right)$ and $c_o\left(O_3\right)$ represent the inlet and outlet ozone concentrations, respectively.

Results and Discussion

Catalyst Characteristics

The morphology and nanostructure of the catalysts were observed by TEM. Figure 1A–C show that the Co₃O₄@SiO₂ nanoparticles were relatively dispersible with an average size of 40 nm. This indicates that PVP can prevent Co₃O₄ nanoparticle agglomeration under hydrothermal conditions. Figure 1D–F show that the spherical Co₃O₄/SiO₂ composites prepared via incipient wetness impregnation were highly dispersed with a relatively smooth external surface. This indicates that a majority of the Co₃O₄ nanoparticles were incorporated into the mesopores (Xie et al., 2011). With regard to the spent Co₃O₄/SiO₂ catalyst, the large aggregates were clearly located on the external surface of the spherical SiO2 support, and indicating that small Co₃O₄ nanoparticles outside of the mesopores easily agglomerated into large Co₃O₄ aggregates during the reaction.

FIGURE 1

FIGURE 1. Scanning electron microscope images of Co₃O₄@SiO₂ (A–C) and 25Co₃O₄/SiO₂ (D–F).

X-ray photoelectron spectroscopy (XPS) tests were performed to detect the chemical state and composition of the element catalyst surface. According to the previously reported Co₃O₄ spectrum (Gao et al., 2021), the Co 2p spectrum of Co₃O₄ (Figure 2A) consists of two peaks, Co 2p_3/2 and Co 2p_1/2, located at 779.9 and 794.8 eV, respectively. However, the Co 2p_3/2 and Co 2p_1/2 peaks in the Co₃O₄@SiO₂ and Co₃O₄/SiO₂ catalysts shifted to approximately 781.0 and 796.0 eV, respectively, both of which occur at higher energies than those of pure Co₃O₄. This shift is mainly due to the interaction between the silica and Co₃O₄ species, which results in a charge transfer from the Co₃O₄ to the SiO₂ support and has a positive impact on the cobalt catalytic performance.

FIGURE 2

FIGURE 2. XPS survey spectra of Co₃O₄@SiO₂ and 25Co₃O₄/SiO₂.

The atomic surface contents of cobalt were 0.8 and 7.6% for the Co₃O₄@SiO₂ and Co₃O₄/SiO₂ catalysts, respectively. This significant difference further confirms that the preparation of Co₃O₄@SiO₂ successfully encapsulated Co₃O₄ into the SiO₂ matrix. The O 1 s spectra of the catalysts are shown in Figure 2B. The main O 1 s peak centered at 533.0 eV represents the lattice oxygen of Co₃O₄ and SiO₂, but is difficult to be accurately distinguished. The oxygen in the unreducible silica has no notable effect on the catalysis of ozone.

Figure 3 shows the nitrogen isothermal adsorption-desorption curves and pore size distributions of the Co₃O₄@SiO₂ and 25Co₃O₄/SiO₂ catalysts. The nitrogen adsorption-desorption isotherms clearly show that both samples have typical hysteresis loops and are classified as type-IV isotherms, thus indicating that the samples have a mesoporous structure. The average pore diameter of the two samples ranges between 6 and 9 nm. The pore volume of Co₃O₄@SiO₂ (0.15 cm³/g) is larger than that of Co₃O₄/SiO₂ (0.11 cm³/g). The specific surface area of Co₃O₄/SiO₂ is 94.8 m²/g, which is 1.5 times greater than that of Co₃O₄@SiO₂ (68.8 m²/g). The specific surface area of a catalyst is generally believed to have a substantial impact on the catalytic activity, in which catalysts with larger specific surface areas usually have higher catalytic activities. Effect of Co₃O₄@SiO₂ and Co₃O₄/SiO₂ on ozone decomposition.

FIGURE 3

FIGURE 3. Nitrogen adsorption-desorption isotherms and BJH pore-size distribution curves of Co₃O₄@SiO₂ and 25Co₃O₄/SiO₂.

The ozone decomposition rates of Co₃O₄@SiO₂ and Co₃O₄/SiO₂ with different Co₃O₄ loadings were evaluated in a gas flow with 40 ppm ozone at 20% relative humidity. The activity of the 10Co₃O₄/SiO₂ catalyst dropped sharply within 1 h, and the 15Co₃O₄/SiO₂ and 20Co₃O₄/SiO₂ catalysts dropped to 94% ozone conversion after 4 h. The time to achieve 100% ozone removal rate increased to 9 h for a Co₃O₄ load of 25%. However, the Co₃O₄@SiO₂ catalyst with 30$$wt% loading achieved the same ozone removal rate as that of 25Co₃O₄/SiO₂. This indicates that the ozone elimination rate is proportional to the Co₃O₄ catalyst load. The XRD patterns of the as-prepared catalysts are shown in Figure 4B, in which all of the obtained samples exhibit the same peaks, corresponding to pure Co₃O₄ (JCPDS No. 42-1,467) (Agilandeswari and Rubankumar 2016). This indicates that the crystalline phase is well maintained during the treatment. The diffraction peaks of both Co₃O₄@SiO₂ and xCo₃O₄/SiO₂ are sharp and intense, and the peak intensities gradually increase with increasing Co₃O₄ catalyst load. The 25Co₃O₄/SiO₂ catalyst exhibits more intense peaks at 36.5 than Co₃O₄@SiO₂ for a similar Co₃O₄ content. This indicates that the Co₃O₄@SiO₂ core-shell structure weakens the intensity of the characteristic peaks, and that the Co₃O₄ crystalline material is well inside the mesoporous silica particles. Effect of 25Co₃O₄@SiO₂ and Co₃O₄/SiO₂ on ozone decomposition under different relative humidity conditions.

FIGURE 4

FIGURE 4. (A) Ozone removal rates and (B) XRD patterns of Co₃O₄@SiO₂ and xCo₃O₄ (x = 10, 15, 20, and 25). Temperature = 25°C; relative humidity = 20%.

Figure 5A,B show the ozone removal rates of 25Co₃O₄@SiO₂ and Co₃O₄/SiO₂, respectively, at relative humidity conditions of 20, 40, and 60%. The 25Co₃O₄@SiO₂ and Co₃O₄/SiO₂ catalysts exhibit similar ozone removal rates at 20% relative humidity. The 25Co₃O₄/SiO₂ catalyst shows 99% ozone conversion for 11 h at 20% relative humidity. The removal rate then sharply drops and ultimately stabilizes at 60%. It is noted that the ozone removal rate sharply decreases with increasing relative humidity, especially when the relative humidity is increased from 40 to 60%. For Co₃O₄@SiO₂, the ozone removal rate begins to decrease during the first 12 h of the reaction runs with a gas flow of 40 ppm ozone, and then decreases to 60% when the reaction has been maintained for 24 h. The ozone removal rate of Co₃O₄@SiO₂ shows a different trend from that of 25Co₃O₄/SiO₂ at 40% relative humidity. When the relative humidity is increased to 60%, the ozone removal rate sharply decreases and remains at 30%, which is approximately 10% higher than that of 25Co₃O₄/SiO₂. This indicates that the main reason for the different performance of the two catalysts is their differing structures. The Co₃O₄ loaded on the surface of SiO₂ is directly exposed to the reaction environment. The accumulation of oxygen atoms and adsorption of water vapor thus lead to catalyst deactivation. In contrast, in the Co₃O₄@SiO₂ catalyst, the Co₃O₄ is wrapped by SiO₂, and which isolates water vapor and prevents it from directly contacting with the Co₃O₄. The deactivation can thus be attributed to the accumulation of oxygen atoms.

FIGURE 5

FIGURE 5. Ozone removal rate of 25Co₃O₄@SiO₂ (A) and Co₃O₄/SiO₂ (B). Temperature = 25°C; relative humidity (RH) = 20, 40, and 60%.

Proposed Mechanism

According to the experimental results, we proposed a possible mechanism involving oxygen vacancies (O_v) as depicted below. Initially, the ozone molecule is adsorbed on the oxygen vacancy of the surface of Co₃O₄ and the ozone decompose into oxygen, while another oxygen atom is left on the surface of Co₃O₄ and form lattice oxygen (O²⁻). Subsequently, the ozone molecule reacts with lattice oxygen and form oxygen and O₂²⁻. Finally, the O₂²⁻ breaks off the Co₃O₄ surface in form of oxygen.

${\mathrm{O}}_3+{\mathrm{O}}_{\mathrm{V}}\to {\mathrm{O}}_2+{\mathrm{O}}^{\mathrm{2-}}\left(R1\right)$

${\mathrm{O}}_3+{\mathrm{O}}^{\mathrm{2-}}\to {\mathrm{O}}_2+{\mathrm{O}}_{\mathrm{2}}^{\mathrm{2-}}\left(R2\right)$

${\mathrm{O}}_{\mathrm{2}}^{\mathrm{2-}}\to {\mathrm{O}}_2+{\mathrm{O}}_{\mathrm{v}}\left(R3\right)$

Conclusion

In this work, Co₃O₄@SiO₂ and xCo₃O₄/SiO₂ (x = 10, 15, 20, and 25) catalysts were successfully synthesized using the hydrothermal method. Under similar loading conditions, the ozone removal rates of Co₃O₄@SiO₂ and 25Co₃O₄/SiO₂ were nearly the same under flow conditions of 40 ppm ozone and 20% relative humidity. When the relative humidity increased to 60%, the ozone removal rate of Co₃O₄@SiO₂ was higher than that of 25Co₃O₄@SiO₂. XRD, XPS, and BET characterizations indicate that the high Co₃O₄@SiO₂ performance is related to the core@shell structure. This study thus provides insight for developing catalysts to effectively remove gaseous ozone.

Data Availability Statement

The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding authors.

Author Contributions

FC and QX conceived the idea. JD, YC, and FH designed and fabricated the sample, ZM, DC, MC, GZ, JK, and SX conducted the the expriment. All the authors contrubuted to analysis of the data and draft of the manuscript.

Funding

National Key Research and Development Program of China 2016YFC0209203 Funding for school-level research projects of Yancheng Institute of Technology xjr2019055.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Supplementary Material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fchem.2021.803464/full#supplementary-material

References

Abbass, O. A., Sailor, D. J., and Gall, E. T. (2017). Effectiveness of Indoor Plants for Passive Removal of Indoor Ozone. Building Environ. 119, 62–70. doi:10.1016/j.buildenv.2017.04.007

CrossRef Full Text | Google Scholar

Abdedayem, A., Guiza, M., Rivas Toledo, F. J., and Ouederni, A. (2017). Ozone Decomposition over Cobalt Supported on Olive Stones Activated Carbon: Effect of Preparation Method on Catalyst Activity. Ozone: Sci. Eng. 39, 435–446. doi:10.1080/01919512.2017.1331729

CrossRef Full Text | Google Scholar

Agilandeswari, K., and Rubankumar, A. (2016). Synthesis, Characterization, Optical, and Magnetic Properties of Co3O4 Nanoparticles by Quick Precipitation. Synth. Reactivity Inorg. Metal-Organic, Nano-Metal Chem. 46, 502–506. doi:10.1080/15533174.2014.988807

CrossRef Full Text | Google Scholar

Alameddine, M., Siraki, A., Tonoyan, L., and Gamal El-Din, M. (2021). Treatment of a Mixture of Pharmaceuticals, Herbicides and Perfluorinated Compounds by Powdered Activated Carbon and Ozone: Synergy, Catalysis and Insights into Non-free OH Contingent Mechanisms. Sci. Total Environ. 777, 146138. doi:10.1016/j.scitotenv.2021.146138

PubMed Abstract | CrossRef Full Text | Google Scholar

Deng, H., Kang, S., Ma, J., Wang, L., Zhang, C., and He, H. (2019). Role of Structural Defects in MnOx Promoted by Ag Doping in the Catalytic Combustion of Volatile Organic Compounds and Ambient Decomposition of O3. Environ. Sci. Technol. 53, 10871–10879. doi:10.1021/acs.est.9b01822

PubMed Abstract | CrossRef Full Text | Google Scholar

Ferrara, F., Pambianchi, E., Pecorelli, A., Woodby, B., Messano, N., Therrien, J.-P., et al. (2020). Redox Regulation of Cutaneous Inflammasome by Ozone Exposure. Free Radic. Biol. Med. 152, 561–570. doi:10.1016/j.freeradbiomed.2019.11.031

PubMed Abstract | CrossRef Full Text | Google Scholar

Ferrara, F., Pambianchi, E., Woodby, B., Messano, N., Therrien, J.-P., Pecorelli, A., et al. (2021). Evaluating the Effect of Ozone in UV Induced Skin Damage. Toxicol. Lett. 338, 40–50. doi:10.1016/j.toxlet.2020.11.023

PubMed Abstract | CrossRef Full Text | Google Scholar

Gao, Z., Zhao, D., Cheng, Q., Zhao, D., Yang, Y., Tian, Y., et al. (2021). Mesoporous SiO 2 ‐Encapsulated Nano‐Co 3 O 4 Catalyst for Efficient CO Oxidation. Chemcatchem 13, 4010–4018. doi:10.1002/cctc.202100602

CrossRef Full Text | Google Scholar

Gong, S., Chen, J., Wu, X., Han, N., and Chen, Y. (2018). In-situ Synthesis of Cu2O/reduced Graphene Oxide Composite as Effective Catalyst for Ozone Decomposition. Catal. Commun. 106, 25–29. doi:10.1016/j.catcom.2017.12.003

CrossRef Full Text | Google Scholar

Gong, S., Li, W., Xie, Z., Ma, X., Liu, H., Han, N., et al. (2017). Low Temperature Decomposition of Ozone by Facilely Synthesized Cuprous Oxide Catalyst. New J. Chem. 41, 4828–4834. doi:10.1039/c7nj00253j

CrossRef Full Text | Google Scholar

Gopi, T., Swetha, G., Chandra Shekar, S., Ramakrishna, C., Saini, B., Krishna, R., et al. (2017). Catalytic Decomposition of Ozone on Nanostructured Potassium and Proton Containing δ-MnO2 Catalysts. Catal. Commun. 92, 51–55. doi:10.1016/j.catcom.2017.01.002

CrossRef Full Text | Google Scholar

Jia, J., Zhang, P., and Chen, L. (2016). Catalytic Decomposition of Gaseous Ozone over Manganese Dioxides with Different Crystal Structures. Appl. Catal. B: Environ. 189, 210–218. doi:10.1016/j.apcatb.2016.02.055

CrossRef Full Text | Google Scholar

Khan, S. A., Khan, S. B., and Asiri, A. M. (2015). Core-shell Cobalt Oxide Mesoporous Silica Based Efficient Electro-Catalyst for Oxygen Evolution. New J. Chem. 39, 5561–5569. doi:10.1039/c5nj00521c

CrossRef Full Text | Google Scholar

Kim, S. H., An, H.-R., Lee, M., Hong, Y., Shin, Y., Kim, H., et al. (2022). High Removal Efficiency of Industrial Toxic Compounds through Stable Catalytic Reactivity in Water Treatment System. Chemosphere 287, 132204. doi:10.1016/j.chemosphere.2021.132204

PubMed Abstract | CrossRef Full Text | Google Scholar

Li, X., Ma, J., and He, H. (2020). Recent Advances in Catalytic Decomposition of Ozone. J. Environ. Sci. 94, 14–31. doi:10.1016/j.jes.2020.03.058

CrossRef Full Text | Google Scholar

Ma, J., Wang, C., and He, H. (2017). Transition Metal Doped Cryptomelane-type Manganese Oxide Catalysts for Ozone Decomposition. Appl. Catal. B: Environ. 201, 503–510. doi:10.1016/j.apcatb.2016.08.050

CrossRef Full Text | Google Scholar

Namdari, M., Lee, C.-S., and Haghighat, F. (2021). Active Ozone Removal Technologies for A Safe Indoor Environment: A Comprehensive Review. Building Environ. 187, 107370. doi:10.1016/j.buildenv.2020.107370

CrossRef Full Text | Google Scholar

Nazaroff, W. W., and Weschler, C. J. (2021). Indoor Ozone: Concentrations and Influencing Factors. Indoor Air 00, 1–21. doi:10.1111/ina.12942

CrossRef Full Text | Google Scholar

Nikolov, P., Genov, K., Konova, P., Milenova, K., Batakliev, T., Georgiev, V., et al. (2010). Ozone Decomposition on Ag/SiO2 and Ag/clinoptilolite Catalysts at Ambient Temperature. J. Hazard. Mater. 184, 16–19. doi:10.1016/j.jhazmat.2010.07.056

PubMed Abstract | CrossRef Full Text | Google Scholar

Ou, J., Yuan, Z., Zheng, J., Huang, Z., Shao, M., Li, Z., et al. (2016). Ambient Ozone Control in a Photochemically Active Region: Short-Term Despiking or Long-Term Attainment? Environ. Sci. Technol. 50, 5720–5728. doi:10.1021/acs.est.6b00345

PubMed Abstract | CrossRef Full Text | Google Scholar

Tang, W.-X., Liu, H.-D., Wu, X.-F., and Chen, Y.-F. (2014a). Higher Oxidation State Responsible for Ozone Decomposition at Room Temperature over Manganese and Cobalt Oxides: Effect of Calcination Temperature. Ozone: Sci. Eng. 36, 502–512. doi:10.1080/01919512.2014.894454

CrossRef Full Text | Google Scholar

Tao, Z., Fu, M., and Liu, Y. (2021b). A Mini-Review of Carbon-Resistant Anode Materials for Solid Oxide Fuel Cells. Sust. Energ. Fuels 5, 5420–5430. doi:10.1039/d1se01300a7

CrossRef Full Text | Google Scholar

Tao, Z., Fu, M., Liu, Y., Gao, Y., Tong, H., Hu, W., et al. (2021a). High-performing Proton-Conducting Solid Oxide Fuel Cells with Triple-Conducting Cathode of Pr0.5Ba0.5(Co0.7Fe0.3)O3-δ Tailored with W. Int. J. Hydrogen Energ. doi:10.1016/j.ijhydene.2021.10.145

CrossRef Full Text | Google Scholar

Xie, R., Li, D., Hou, B., Wang, J., Jia, L., and Sun, Y. (2011). Solvothermally Derived Co3O4@m-SiO2 Nanocomposites for Fischer-Tropsch Synthesis. Catal. Commun. 12, 380–383. doi:10.1016/j.catcom.2010.10.010

CrossRef Full Text | Google Scholar

Yang, S., Zhu, Z., Wei, F., and Yang, X. (2017). Carbon Nanotubes/Activated Carbon Fiber Based Air Filter media for Simultaneous Removal of Particulate Matter and Ozone. Building Environ. 125, 60–66. doi:10.1016/j.buildenv.2017.08.040

CrossRef Full Text | Google Scholar

Yu, Y., Ji, J., Li, K., Huang, H., Shrestha, R. P., Kim Oanh, N. T., et al. (2020). Activated Carbon Supported MnO Nanoparticles for Efficient Ozone Decomposition at Room Temperature. Catal. Today 355, 573–579. doi:10.1016/j.cattod.2019.05.063

CrossRef Full Text | Google Scholar

Zhu, G., Zhu, W., Lou, Y., Ma, J., Yao, W., Zong, R., et al. (2021). Encapsulate α-MnO2 Nanofiber within Graphene Layer to Tune Surface Electronic Structure for Efficient Ozone Decomposition. Nat. Commun. 12, 10. doi:10.1038/s41467-021-24424-x

PubMed Abstract | CrossRef Full Text | Google Scholar