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Song X, Wang H, Li Z, Du CF, Guo R. A Review of MnO 2 Composites Incorporated with Conductive Materials for Energy Storage. CHEM REC 2022; 22:e202200118. [PMID: 35686874 DOI: 10.1002/tcr.202200118] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/19/2022] [Indexed: 01/06/2023]
Abstract
Manganese dioxide (MnO2 ) has been widely used in the field of energy storage due to its high specific capacitance, low cost, natural abundance, and being environmentally friendly. However, suffering from poor electrical conductivity and high dissolvability, the performance of MnO2 can no longer meet the needs of rapidly growing technological development, especially for the application as electrode material in metal-ion batteries and supercapacitors. In this review, recent studies on the development of binary or multiple MnO2 -based composites with conductive components for energy storage are summarized. Firstly, general preparing methods for MnO2 -based composites are introduced. Subsequently, the binary and multiple MnO2 -based composites with carbon, conducting polymer, and other conductive materials are discussed respectively. The improvement in their performance is summarized as well. Finally, perspectives on the practical applications of MnO2 -based composites are presented.
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Guo Y, Long J, Huang J, Yu G, Wang Y. Can the commonly used quenching method really evaluate the role of reactive oxygen species in pollutant abatement during catalytic ozonation? WATER RESEARCH 2022; 215:118275. [PMID: 35305491 DOI: 10.1016/j.watres.2022.118275] [Citation(s) in RCA: 64] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 02/21/2022] [Accepted: 03/07/2022] [Indexed: 06/14/2023]
Abstract
Reactive oxygen species (ROS) such as hydroxyl radicals (•OH), superoxide radicals (O2•-), and singlet oxygen (1O2) have often been suggested to play a role in ozone-resistant pollutant abatement during catalytic ozonation. However, there are significant controversies regarding their relative importance in literature. Currently, the role of ROS in pollutant abatement is commonly evaluated by the quenching method based on the assumption that the added ROS quenchers (e.g., tert-butanol (TBA) and para-benzoquinone (pBQ)) quench only the target ROS, but do not considerably influence other reaction mechanisms of catalytic ozonation. However, we hypothesized that this assumption is possibly unrealistic and a main cause for the controversies reported in literature. To test this hypothesis, this study evaluated the effects of six commonly used ROS quenchers (TBA, pBQ, methanol (MeOH), 4-chloro-7-nitrobenzo-2-oxa-1,3-dizole (NBD-Cl), furfuryl alcohol (FFA), and sodium azide (NaN3)) on the mechanism of catalytic ozonation with manganese dioxide. The results show that rather than only quenching their target ROS, these quenchers can profoundly change the catalytic ozonation system through various mechanisms, e.g., interrupting the radical chain reaction of O3 decomposition, blocking the active sites of catalysts, and consuming O3 in the system. Due to the significant confounding effects of ROS quenchers on the reaction mechanism, the quenching method actually cannot reveal the role of ROS in pollutant abatement and often misinterpreted the catalytic ozonation mechanism. The results indicate that the commonly used quenching method is probably not an appropriate way to investigate the role of ROS in pollutant abatement during catalytic ozonation, and many previously reported mechanisms obtained with the quenching method may need a revisit.
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Chen Y, Liu R, Wu X, Liu Y, Fu J, Ou H. Surface characteristic and sinking behavior modifications of microplastics during potassium permanganate pre-oxidation. JOURNAL OF HAZARDOUS MATERIALS 2022; 422:126855. [PMID: 34425434 DOI: 10.1016/j.jhazmat.2021.126855] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/29/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Microplastics (MPs) occur in the source water of worldwide drinking water treatment plants (DWTPs). Pre-oxidation treatments become the initial stage for MPs treatment in DWTPs. Investigating the modifications of MPs after pre-oxidations is important to understand their fate in DWTPs. In this study, potassium permanganate oxidation (PPO) was applied to treat four high abundant MPs in DWTPs, including polyethylene (PE), polyethylene terephthalate (PET), polyvinylchloride (PVC) and polystyrene (PS). Influences of polymer types, sizes and pH were considered. After 10 mg L-1 PPO, only slight corrosions were observed on all MPs. Whereas, the appearances of O-Mn spectrum and the observation of nano-scale particles indicated the generation of nascent state Mn-oxides (MnO2) on MPs surface. This adhesion of MnO2 contributed to increasing density and hydrophilicity. As a result, the sinking performance of MPs was enhanced, e.g. the sinking ratio of 6.5 µm MPs increased 30% (PET), 20% (PVC) and 30% (PS) compared with pristine ones upon pH 7 PPO. These results implied that the practical PPO can enhance the sinking behavior of MPs. Of note, PE seems to be persistent and requires special concern.
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Lopes SV, Walczak P, Janowski M, Reis RL, Silva-Correia J, Oliveira JM. Cytocompatible manganese dioxide-based hydrogel nanoreactors for MRI imaging. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2021; 134:112575. [PMID: 35525742 DOI: 10.1016/j.msec.2021.112575] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 11/10/2021] [Accepted: 11/24/2021] [Indexed: 01/07/2023]
Abstract
The application of nanoparticles in magnetic resonance imaging (MRI) has been greatly increasing, due to their advantageous properties such as nanoscale dimension and tuneability. In this context, manganese (Mn2+)-based nanoparticles have been greatly investigated, due to their valuable use as a contrast agent, improving signal intensity and specificity in MRI (manganese-enhanced MRI, MEMRI). Additionally, Mn2+ can act as scavengers of reactive oxygen species (ROS), commonly present in the inflammatory processes of neurodegenerative diseases. The aim of the present study was to develop nanoreactors, which can be used as contrast-agent in MEMRI. Several blends of methacrylated gellan gum (GG-MA) and hyaluronic acid (HA) were embedded with different types of manganese dioxide (MnO2) nanoparticles and further physico-chemically characterized. Dynamic light scattering, scanning electron microscopy, water uptake and degradation studies were performed. In vitro cytotoxicity of the different formulations was also evaluated using an immortalized rat fibroblast cell line L929, up to 72 h of culturing. Synthesized nanoparticles were obtained with an average size of 70 nm and round-shaped morphology. The stability of the different formulations of hydrogels was not affected by nanoparticles' concentration or HA ratio. The presence of synthesized MnO2 (MnO2_S) nanoparticles reduced hydrogels' cytocompatibility, whereas the commercially available type 1 (MnO2_C1) nanoparticles were less toxic to cells. Additionally, cell proliferation and viability were enhanced when a lower content of HA was present. Higher concentrations (75 and 100 ng/mL) of MnO2_S and MnO2_C1 nanoparticles did not negatively affected cell viability, whereas the opposite effect was observed for the commercial type 2 (MnO2_C2) nanoparticles. Further studies are required to evaluate the potential application of the most promising nanoreactors' formulations for combined application in MEMRI and as ROS scavengers.
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Xu Z, Yang W, Si W, Chen J, Peng Y, Li J. A novel γ-like MnO 2 catalyst for ozone decomposition in high humidity conditions. JOURNAL OF HAZARDOUS MATERIALS 2021; 420:126641. [PMID: 34329114 DOI: 10.1016/j.jhazmat.2021.126641] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 06/29/2021] [Accepted: 07/11/2021] [Indexed: 06/13/2023]
Abstract
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.
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Li J, Zhou L, Song Y, Yu X, Li X, Liu Y, Zhang Z, Yuan Y, Yan S, Zhang J. Green fabrication of porous microspheres containing cellulose nanocrystal/MnO 2 nanohybrid for efficient dye removal. Carbohydr Polym 2021; 270:118340. [PMID: 34364594 DOI: 10.1016/j.carbpol.2021.118340] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 05/17/2021] [Accepted: 06/13/2021] [Indexed: 01/01/2023]
Abstract
Microspheres based on cellulose nanocrystal (CNC)/metal oxide hybrid materials have great application prospects in wastewater treatment due to simultaneously adsorption, degradation ability, easily separation and recycling properties. However, the relatively small porosity and specific surface area of the CNC-based microspheres limit their adsorption ability. Herein, we reported a facile strategy to prepare porous microsphere based on CNC/MnO2 by freeze-drying the air-bubble templated emulsion, in which the sodium alginate (SA) was used as the crosslinked matrix. Thus-obtained CNC/MnO2/SA microspheres showed low density of 0.027 g/cm3 and high porosity of 98.23%. Benefiting from the high porosity, synergetic effect of CNC electrostatic adsorption and oxidative degradation ability of MnO2, the decolorization ratio of methylene blue (800 mg/mL) could be up to 95.4% in 10 min, and the equilibrium decolorization could reach 114.5 mg/g. This study provides a green and facile strategy to design porous CNC-based material for dye wastewater treatment.
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Veroniaina H, Wu Z, Qi X. Innate tumor-targeted nanozyme overcoming tumor hypoxia for cancer theranostic use. J Adv Res 2021; 33:201-213. [PMID: 34603790 PMCID: PMC8463960 DOI: 10.1016/j.jare.2021.02.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 02/16/2021] [Accepted: 02/17/2021] [Indexed: 01/11/2023] Open
Abstract
Introduction Hypoxic tumor microenvironment (TME) is the major contributor to cancer metastasis, resistance to chemotherapy, and recurrence of tumors. So far, no approved treatment has been available to overcome tumor hypoxia. Objectives The present study aimed to relieve tumor hypoxia via a nanozyme theranostic nanomaterial as well as providing magnetic resonance imaging (MRI)-guided therapy. Methods Manganese dioxide (MnO2) was used for its intrinsic enzymatic activity co-loaded with the anti-cancer drug Doxorubicin (Dox) within the recombinant heavy-chain apoferritin cavity to form MnO2-Dox@HFn. Following the synthesis of the nanomaterial, different characterizations were performed as well as its nanozyme-like ability. This nanoplatform recognizes tumor cells through the transferrin receptors 1 (TfR1) which are highly expressed on the surface of most cancer cells. The cellular uptake was confirmed by flow cytometry and fluorescence spectroscopy. In vitro and in vivo studies have been investigated to evaluate the hypoxia regulation, MRI ability and anti-tumor activity of MnO2-Dox@HFn. Results Being a TME-responsive nanomaterial, MnO2-Dox@HFn exerted both peroxidase and catalase activity that mainly produce massive oxygen and Mn2+ ions. Respectively, these products relieve the unfavorable tumor hypoxia and also exhibit T1-weighted MRI with a high longitudinal relaxivity of 33.40 mM. s−1. The utility of MnO2-Dox@HFn was broadened with their efficient anti-cancer activity proved both in vitro and in vivo. Conclusions MnO2-Dox@HFn successfully overcome tumor hypoxia with double potentials enzymatic ability and diagnostic capacity. This investigation could ignite the future application for cancer theranostic nanozyme therapy.
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Online evaluation of the catalytic performance of MnO 2 and its application in H 2S cataluminescence sensing. Anal Chim Acta 2021; 1180:338883. [PMID: 34538311 DOI: 10.1016/j.aca.2021.338883] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/20/2021] [Accepted: 07/23/2021] [Indexed: 02/05/2023]
Abstract
As a catalyst widely used in industry, manganese dioxide (MnO2) has different crystalline forms and shows excellent performance in catalytic reactions. Therefore, it is of significance to rapidly evaluate the catalytic performance of MnO2 online. In this paper, a highly efficient evaluation method based on H2S cataluminescence (CTL) sensing was proposed for MnO2 with different crystalline forms. Firstly, α-, β- and δ-MnO2 were synthesized successfully and performed diacritical CTL behaviours in the catalytic oxidation of H2S. Based on these interesting phenomena, the catalytic performance of α-, β- and δ-MnO2 was efficiently evaluated online through CTL method for the first time. Results showed that β-MnO2 had the best catalytic oxidation performance, followed by α- and δ-MnO2, and the reactive oxygen species of MnO2 was the most significant influencing factor. Subsequently, β-MnO2 was selected to design a CTL sensor for H2S detection with a wide linear range (2.43-29.1 μg/mL) and a low limit of detection (LOD, S/N = 3, 0.280 μg/mL). This work not only provided a new and feasible method for online evaluation of the catalytic performance of materials, but also designed a CTL sensor for H2S determination with high selectivity and sensitivity.
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Fu L, Wu X, Zhu Y, Yao L, Wu C, Cheng H, Xu Y, Hu J, Gao W. Iodinated disinfection byproduct formation in a MnO 2/I -/EPS system. CHEMOSPHERE 2021; 280:130643. [PMID: 33971409 DOI: 10.1016/j.chemosphere.2021.130643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/13/2021] [Accepted: 04/20/2021] [Indexed: 06/12/2023]
Abstract
Manganese dioxide (MnO2) is a Mn deposit widely accumulated in the corrosion layer of pipelines, and iodide (I-) is a halogen ion frequently detected in waters. The biofilm dwelling on the corrosion scales often secretes extracellular polymeric substances (EPS) into drinking water. The paper aimed to study the I- oxidation by MnO2 and iodinated disinfection byproducts (I-DBPs) formation with biofilm EPS as a precursor. More than 93% of formed free iodine was finally converted into organic iodine in the MnO2/I-/EPS system. Compared with humic acid, EPS had a lower carbonaceous I-DBPs (C-IDBPs) formation while a higher nitrogenous I-DBPs (N-IDBPs) formation. The formation of iodomethanes (I-THMs), iodoacetonitriles (I-HANs) and iodoacetic acids (I-HAAs) decreased with the increase of pH due to the weakening of polarization effect and redox potential, while the iodoacetamides (I-HAcAms) formation achieved the maximum at pH 6.0 due to the difference between the hydrolysis rate of I-HANs and decomposition rate of I-HAcAms. The I-DBPs formation was positively correlated with I- concentration, while negatively correlated with MnO2 dose. Protein components displayed a higher formation of N-IDBPs and C-IDBPs than polysaccharide components due to higher nitrogen proportion and more iodination sites. Among 20 protein monomers, aspartic acid was considered as the most important precursor of the four investigated I-DBPs species. The paper is helpful to understand the I-DBPs formation when I- in the bulk water come into contact with Mn deposits attached by biofilm.
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Du C, Zhang Z, Tan S, Yu G, Chen H, Zhou L, Yu L, Su Y, Zhang Y, Deng F, Wang S. Construction of Z-scheme g-C 3N 4 / MnO 2 /GO ternary photocatalyst with enhanced photodegradation ability of tetracycline hydrochloride under visible light radiation. ENVIRONMENTAL RESEARCH 2021; 200:111427. [PMID: 34062202 DOI: 10.1016/j.envres.2021.111427] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/17/2021] [Accepted: 05/24/2021] [Indexed: 05/27/2023]
Abstract
A facile wet-chemical method was adopted to synthesize g-C3N4/MnO2/GO heterojunction photocatalyst for visible-light photodegradation of tetracycline hydrochloride (TC). The addition of MnO2 and GO increased the absorption of visible light and the specific surface area of the photocatalyst. The results of photoluminescence, electrochemical impedance spectroscopy, and photocurrent response indicated that CMG-10 had the lowest electron-hole recombination probability, which was beneficial for the photocatalytic reaction. The ternary photocatalyst exhibited enhanced photoelectric performance and superior photocatalytic activity with 91.4% removal of TC (10 mg/L) under a mere 60 min visible light illumination, which showed enhanced photocatalytic degradation when compared with binary (CM, 77.95%; CG, 78.83%) and single (C3N4, 55.5%; MnO2, 36.41%) photocatalysts. A pH of 6 was optimal for the CMG-10 photocatalytic degradation of TC, and the optimal photocatalyst dosage was 0.5 g/L. Common coexisting ions influenced the removal of TC by influencing the production of active species. The catalyst is stable and reusable with only a 10% reduction in removal efficiency after four cycles. According to the active species analysis, the Z-scheme mechanism was a charge transfer behavior in the composite photocatalyst, which could prevent the recombination of photogenerated carriers. This study presents a photocatalytic approach to the effective removal of TC from water bodies, which provides practical implications to advance the use of photocatalytic technology in the restoration of aqueous environmental pollution.
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Cheng M, Yao C, Su Y, Liu J, Xu L, Hou S. Synthesis of membrane-type graphene oxide immobilized manganese dioxide adsorbent and its adsorption behavior for lithium ion. CHEMOSPHERE 2021; 279:130487. [PMID: 33865165 DOI: 10.1016/j.chemosphere.2021.130487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 03/28/2021] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
Recently, there has been an urgent need to develop new materials and technologies for extracting lithium ions. Herein, the membrane-type adsorbent of manganese dioxide (MnO2) is prepared by a vacuum filtration method using graphene oxide (GO) as a binder and amino-β-cyclodextrin (amino-β-CD) as an adjuvant. The results of thermogravimetric analysis show that MnO2 is successfully immobilized on GO layers with a content of about 24 wt%, which enabled rapid adsorb lithium ions from the ionic solution. In addition, the permeation experiment shows the membrane has specific selectivity for lithium ion transport and adsorption, which is manifested in the selectivity ratios of K+/Li+, Na+/Li+ and K+/Na+ to 2.5, 3.2 and 0.8, respectively. Adsorption experiments show that GO-β-CD/MnO2 membrane has a high adsorption capacity for lithium ions (37.5 mg g-1). The adsorption kinetic curve indicates that the lithium adsorption process is controlled by the chemical adsorption mechanism. In the enrichment experiment, the concentration of lithium ions from seawater can be enriched to 1.2 mg L-1 after 100 cycles. The results suggest that the developed GO-β-CD/MnO2 membrane could effectively extract lithium ions from seawater.
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Sun B, Zhang Y, Gong Z, Zhang J, Zhang J. Reducing substances-enhanced degradation of pollutants by permanganate: The role of in situ formed colloidal MnO 2. CHEMOSPHERE 2021; 276:130203. [PMID: 33725625 DOI: 10.1016/j.chemosphere.2021.130203] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 06/12/2023]
Abstract
Permanganate is one of common oxidants used for organic pollutant abatement in water treatment. This study showed that the degradation rate of bisphenol A (BPA) by permanganate at pH 5.0 in the presence of aniline is much higher than that in the absence of aniline. 2, 5, and 10 μM of aniline enhanced BPA degradation rate by 104%, 326% and 601%, respectively. Colloidal MnO2 was formed through the reduction of permanganate by aniline and contributed to BPA oxidation considerably. The reactivity of MnO2 is sensitive to pH and is high under acidic conditions, resulting in the observed enhancement of aniline on BPA removal by permanganate at pH < 7.0. The role of MnO2 was further confirmed by the relationship of MnO2 formation and BPA/aniline removal, the inhibitory effect of Ca2+ on the oxidation of BPA in the presence of aniline. Besides the aniline/BPA system, the pollutants which react with permanganate rapidly are likely to enhance the degradation of coexisting pollutants which show high reactivity towards MnO2. Due to the reduction of permanganate and stabilization of the in situ formed colloidal MnO2 by water matrix, the oxidation rate of pollutant in real water is higher than that in pure water.
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Min JS, Hong JY, Lim YG, Ahn JW, Park K. Oxygen-generating glycol chitosan- manganese dioxide nanoparticles enhance the photodynamic effects of chlorin e6 on activated macrophages in hypoxic conditions. Int J Biol Macromol 2021; 184:20-28. [PMID: 34118287 DOI: 10.1016/j.ijbiomac.2021.06.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/24/2021] [Accepted: 06/05/2021] [Indexed: 01/10/2023]
Abstract
This study aimed to investigate the use of glycol chitosan (GC) for the synthesis of MnO2 nanoparticles (NPs) and to evaluate whether the prepared GC-MnO2 NPs enhance the light-triggered photodynamic effects of chlorin e6 (Ce6) via the generation of oxygen and alleviation of hypoxia in lipopolysaccharide (LPS)-activated macrophages (RAW 264.7), which produce excessive amounts of reactive oxygen species (ROS). GC-MnO2 NPs were synthesized by a simple reaction between GC and KMnO4 in water. The prepared GC-MnO2 NPs were spherical in shape, with a mean diameter of approximately 60 nm. The particles effectively generated oxygen via H2O2-induced degradation under hypoxic conditions, which led to an increase in the singlet oxygen levels upon laser irradiation. Furthermore, GC-MnO2 NPs significantly enhanced the light-triggered photodynamic effects of Ce6 on activated macrophages under hypoxic conditions, as shown by the increased levels of cell death and cell membrane damage in activated macrophages. Therefore, these results suggest that GC can be used as an alternative natural polymer for the synthesis of MnO2 NPs and that oxygen-generating GC-MnO2 NPs enhance the light-triggered photodynamic effects of Ce6 on activated macrophages by alleviating hypoxia.
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Minale M, Gu Z, Guadie A, Li Y, Wang Y, Meng Y, Wang X. Hydrous manganese dioxide modified poly(sodium acrylate) hydrogel composite as a novel adsorbent for enhanced removal of tetracycline and lead from water. CHEMOSPHERE 2021; 272:129902. [PMID: 33592510 DOI: 10.1016/j.chemosphere.2021.129902] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 01/14/2021] [Accepted: 02/03/2021] [Indexed: 06/12/2023]
Abstract
In this study, hydrous manganese dioxide (HMO) modified poly(sodium acrylate) (PSA) hydrogel was produced for the first time to remove tetracycline(TC) and lead(Pb(II)) from water. The as-prepared composite was characterized using various techniques, such as SEM-EDS, FTIR, XRD, BET, and XPS, to elucidate the successful loading of HMO and analyze subsequent sorption mechanisms. Different influencing parameters such as adsorbent dose, initial concentration of adsorbates, reaction time, solution pH, and temperature were also investigated. The adsorption kinetic studies of both TC and Pb(II) removal indicated that equilibrium was achieved within 12 h, with respective removal rates of 91.9 and 99.5%, and the corresponding adsorption data were fitted to the second-order kinetics model. According to the adsorption isotherm studies, the sorption data of TC best fitted to the Langmuir isotherm model while the adsorption data of Pb(II) were explained by the Freundlich isotherm model. The maximum adsorption capacities of both TC and Pb(II) were found to be 475.8 and 288.7 mg/g, respectively, demonstrating excellent performances of the adsorbent. The uptake capacity of PSA-HMO was significantly influenced by the level of solution pH, in which optimum adsorption amount was realized at pH 4.0 in the TC and Pb(II) systems, respectively. Thermodynamic studies showed the process of TC and Pb(II) adsorptions were endothermic and spontaneous. Overall this study elucidated that PSA-HMO composite can be a promising candidate for antibiotics and heavy metal removal in water treatment applications.
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Detection of silver through amplified quenching of fluorescence from polyvinyl pyrrolidone-stabilized copper nanoclusters. Mikrochim Acta 2021; 188:212. [PMID: 34052959 DOI: 10.1007/s00604-021-04873-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 05/20/2021] [Indexed: 10/21/2022]
Abstract
Silver ion detection with ultra-high sensitivity was established. We synthesized copper nanoclusters (CuNCs) with blue fluorescence through a one-pot process. Instead of a direct quencher toward the CuNCs, silver ions activated the strong oxidation from persulfate and subsequently converted divalent manganese ion into manganese dioxide (MnO2). The surface charges of MnO2 and the CuNCs brought them together and quenched the fluorescence from the latter. Due to silver ions' role as the catalyst in the process, it cycled and even a small amount leads to a significant fluorescence change. This signaling provided the determination of silver ions in the range 5 pM~1 nM, with a detection limit of 1.2 pM. The method is selective, and its applicability was validated through practical water sample analyses.
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High-performance reversible aqueous zinc-ion battery based on iron-doped alpha- manganese dioxide coated by polypyrrole. J Colloid Interface Sci 2021; 598:419-429. [PMID: 33930746 DOI: 10.1016/j.jcis.2021.04.057] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/11/2021] [Accepted: 04/12/2021] [Indexed: 11/22/2022]
Abstract
The development of zinc-ion storage cathode materials for aqueous zinc-ion batteries (AZIBs) is a necessary step for the construction of large-scale electrochemical energy conversion and storage devices. Iron-doped alpha-manganese dioxide (α-MnO2) nanocomposites were achieved in this study via pre-intercalation of Fe3+ during the formation of α-MnO2 crystals. A polypyrrole (PPy) granular layer was fabricated on the surface of α-MnO2 using acid-catalyzed polymerization of pyrroles. The pre-intercalation of Fe3+ effectively enlarges the lattice spacing of α-MnO2 and consequently decreases the hindrance for Zn2+ insertion/extraction in the iron-doped α-MnO2 coated by PPy (Fe/α-MnO2@PPy) composite. Meanwhile, the PPy buffer layer can ameliorate electron and ion conductivity and prevent dissolution of α-MnO2during the charge/discharge process. This unique structure makes the Fe/α-MnO2@PPy composite an efficient zinc-ion storage cathode for AZIBs. The targeted Fe/α-MnO2@PPy cathode achieves superior performance with reversible specific capacity (270 mA h g-1 at 100 mA g-1) and exhibits highdiffusioncoefficientof 10-10-10-14 cm-2 s-1. Therefore, a feasible approach is implemented on advanced electrode materials using in AZIBs for practical applications.
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Cai Y, He J. Degradation of ciprofloxacin by the Mn cycle system (MnCS): Construction, characterization and bacterial analysis. ENVIRONMENTAL RESEARCH 2021; 195:110860. [PMID: 33581090 DOI: 10.1016/j.envres.2021.110860] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/03/2021] [Accepted: 02/04/2021] [Indexed: 06/12/2023]
Abstract
The release of Mn(II) occurs in the degradation of organic matters by manganese ore (MnO2), resulting in a reduced efficiency. During the degradation of ciprofloxacin (CIP), in a biofilter, this paper put forward a novel method that similar to the geo-cycle of Mn (MnCS) on the Earth to regenerate MnO2. The freshly prepared MnO2 was suitable for the use in the MnCS. It indicated that the mutual conversion between Mn(II), Mn(III), and Mn(IV) in the MnCS, which was driven by CIP and manganese oxidizing bacteria (MnOB), could maintain the activity of MnO2. The MnCS showed feasibility in the coexistence of ammonia or humic acid, and provided a kinetic degradation. The physicochemical features of MnO2 before and after bio-regeneration were characterized by TEM, XRD, BET, and XPS. It was found that the morphological structure of MnO2 became loose and the maximum peak of pore size distribution became smaller, but the increase of surface area, the change of Mn(III/IV) content, and the decrease of crystallinity favored the bio-regeneration process. Moreover, as a mediator in the MnCS, the group of MnOB was dramatically inhibited by CIP, and the bacterial community had changed significantly. The typical MnOB shared low abundance in the biofilter, while the rarely reported genera (e.g. Sphingomonas) that related to the formation of Mn deposits appeared to be involved in the MnCS.
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Yang J, Ao Z, Wu H, Zhang S. Immobilization of chitosan-templated MnO 2 nanoparticles onto filter paper by redox method as a retrievable Fenton-like dip catalyst. CHEMOSPHERE 2021; 268:128835. [PMID: 33158502 DOI: 10.1016/j.chemosphere.2020.128835] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/20/2020] [Accepted: 10/29/2020] [Indexed: 06/11/2023]
Abstract
By exploiting the hydrophilicity of cellulose filter paper (FP) and the excellent chelating property of chitosan (CH) for Mn2+, we have designed an efficient and retrievable dip catalyst MnO2/CH-FP for Fenton-like degradation of methylene blue (MB) over a wide pH range from 2.8 to 11.2. The MnO2 nanoparticles were uniformly immobilized in the CH-FP matrix by in-situ redox precipitation method where Mn(NO3)2 was treated with KMnO4 at mild conditions. A series of MnO2/CH-FP hybrids with different MnO2 loading were fabricated via varying concentration of Mn(NO3)2 solution, and their structure-function relationships were discussed based on detailed characterization. The optimal catalyst 1.0MnO2/CH-FP could cooperate with multiple low-concentration dosages of H2O2 to efficiently degrade 95.6% MB in 90 min (50 mg L-1 MB, 1 g L-1 catalyst, 30 mg L-1 H2O2, pH 7). It is also shown that 1.0MnO2/CH-FP could still keep 83.3% degradation efficiency of MB after six cycles. Moreover, the activity of this composite greatly surpassed that of bare MnO2 for nearly 50%, owing to its larger surface area and more accessible active sites. This method for preparing MnO2/CH-FP could effectively avoid the agglomeration of MnO2 nanoparticles and make the reaction turn on/off almost instantaneously by mere insertion/removal.
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Zhou Y, Gao Y, Jiang J, Shen YM, Pang SY, Song Y, Guo Q. A comparison study of levofloxacin degradation by peroxymonosulfate and permanganate: Kinetics, products and effect of quinone group. JOURNAL OF HAZARDOUS MATERIALS 2021; 403:123834. [PMID: 33264920 DOI: 10.1016/j.jhazmat.2020.123834] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/10/2020] [Accepted: 08/27/2020] [Indexed: 06/12/2023]
Abstract
Permanganate (Mn(VII)) as a selective oxidant has been widely used in water treatment process. Recently, peroxymonosulfate (PMS) was recognized as an emerging selective oxidant, which showed appreciable reactivity toward organic compounds containing electron-rich functional groups. In this study, the oxidation of a model fluoroquinolone antibiotic levofloxacin (LEV) by Mn(VII) and PMS was comparatively investigated. Degradation of LEV by PMS followed second-order kinetics and showed strong pH dependency with apparent second-order rate constants (kapp) of 0.15-26.52 M-1 s-1 at pH 5.0-10.0. Oxidation of LEV by Mn(VII) showed autocatalysis at pH 5.0-7.0, while no autocatalysis was observed at pH 8.0-10.0 (kapp = 2.23-4.16 M-1 s-1). Such unusual oxidation kinetics was attributed to the in-situ formed MnO2 from Mn(VII) consumption. The performance of PMS and Mn(VII) for the degradation of LEV was also examined in real waters. PMS primarily react with the aliphatic N4 amine on the piperazine ring of LEV, and Mn(VII) reacted with both the aliphatic N4 amine and aromatic N1 amine. Both PMS and Mn(VII) could efficiently eliminate the antibiotic activity of LEV. Benzoquinone showed activating effect on both PMS and Mn(VII) oxidation, but their activation mechanisms were totally different.
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Ren F, Chen X, Xing R, Du Y. Rod-like MnO 2 boost Pd/reduced graphene oxide nanocatalyst for ethylene glycol electrooxidation. J Colloid Interface Sci 2021; 582:561-568. [PMID: 32911405 DOI: 10.1016/j.jcis.2020.07.133] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/26/2020] [Accepted: 07/27/2020] [Indexed: 01/19/2023]
Abstract
Anode catalyst is one of the core components of fuel cell, but its poor catalytic activity, short lifespan, and high price are tricky problems to the commercialization of fuel cell. Herein, a novel rod-like MnO2 decorated reduced graphene oxide (RGO) supported Pd hybrid (Pd/RGO-MnO2) has been designed, which manifests more negative onset oxidation potential, higher peak current density, and better long-term stability relative to Pd/RGO and pure Pd catalysts when serving for ethylene glycol electrooxidation. This enhancement may be due to the addition of MnO2, which can effectively promote the adsorption of hydroxyl at a lower potential and produce a strong electronic interaction with Pd, as confirmed by X-ray photoelectron spectroscopy (XPS) technique. In view of its excellent performance and low cost, Pd/RGO-MnO2 is considered to be a potential and effective anode catalyst for DEGFCs.
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Dong G, Han R, Pan Y, Zhang C, Liu Y, Wang H, Ji X, Dahlgren RA, Shang X, Chen Z, Zhang M. Role of MnO 2 in controlling iron and arsenic mobilization from illuminated flooded arsenic-enriched soils. JOURNAL OF HAZARDOUS MATERIALS 2021; 401:123362. [PMID: 32629343 DOI: 10.1016/j.jhazmat.2020.123362] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/10/2020] [Accepted: 06/29/2020] [Indexed: 06/11/2023]
Abstract
This study examined the role of intermittent illumination/dark conditions coupled with MnO2-ammendments to regulate the mobility of As and Fe in flooded arsenic-enriched soils. Addition of MnO2 particles with intermittent illumination led to a pronounced increase in the reductive-dissolution of Fe(III) and As(V) from flooded soils compared to a corresponding dark treatments. A higher MnO2 dosage (0.10 vs 0.02 g) demonstrated a greater effect. Over a 49-day incubation, maximum Fe concentrations mobilized from the flooded soils amended with 0.10 and 0.02 g MnO2 particles were 2.39 and 1.85-fold higher than for non-amended soils under dark conditions. The corresponding maximum amounts of mobilized As were at least 92 % and 65 % higher than for non-amended soils under dark conditions, respectively. Scavenging of excited holes by soil humic/fulvic compounds increased mineral photoelectron production and boosted Fe(III)/As(V) reduction in MnO2-amended, illuminated soils. Additionally, MnO2 amendments shifted soil microbial community structure by enriching metal-reducing bacteria (e.g., Anaeromyxobacter, Bacillus and Geobacter) and increasing c-type cytochrome production. This microbial diversity response to MnO2 amendment facilitated direct contact extracellular electron transfer processes, which further enhanced Fe/As reduction. Subsequently, the mobility of released Fe(II) and As(III) was partially attenuated by adsorption, oxidation, complexation and/or coprecipitation on active sites generated on MnO2 surfaces during MnO2 dissolution. These results illustrated the impact of a semiconducting MnO2 mineral in regulating the biogeochemical cycles of As/Fe in soil and demonstrated the potential for MnO2-based bioremediation strategies for arsenic-polluted soils.
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Kamran U, Park SJ. MnO 2-decorated biochar composites of coconut shell and rice husk: An efficient lithium ions adsorption-desorption performance in aqueous media. CHEMOSPHERE 2020; 260:127500. [PMID: 32688308 DOI: 10.1016/j.chemosphere.2020.127500] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 05/07/2023]
Abstract
Lithium (Li+) is used in various applications involving pharmaceuticals, textile dyes, and batteries. Therefore, the demand for environmentally friendly and effective materials for Li+ uptake and recovery continues to increase. Herein, rice husk (RH) and coconut shell (CS) biomasses were used to fabricate honeycomb-networked biochar (BC) precursors via slow pyrolysis. RHBC- and CSBC-based MnO2 composites were synthesized by depositing MnO2 in various ratios onto RHBC and CSBC by varying the KMnO4 concentration (2%, 3%, and 4%), followed by simple ultrasonication and heat-treatment methodologies. The structural and physicochemical properties of all of the fabricated composites were analyzed using several different instrumental methods. The batch adsorption experiments were performed for comparative Li+-adsorption studies of RHBC-Mnx and CSBC-Mnx composites by optimizing several parameters (pH, adsorbent dose, Li+ initial concentration, and contact time). The comparative adsorption analysis revealed that the RHBC-Mnx composites exhibited stronger Li+-adsorption ability than the CSBC-Mnx composites and that increasing the MnO2 deposition to 3% in both cases led to maximum Li+ adsorption capacities (62.85 mg g-1 and 57.8 mg g-1), respectively. The kinetic studies show that Li+ adsorption proceeds through the pseudo-second-order mechanism. Li+ recovery was successfully carried out using HCl (eluting agent), thereby demonstrating the benefits of synthesized composites at the industrial scale. The current work indicates that the fabricated RHBC-Mnx and CSBC-Mnx composites may have potential for use as economical composites in eco-friendly applications such as Li+ adsorption and recovery from aqueous media.
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Peng S, Yang X, Strong J, Sarkar B, Jiang Q, Peng F, Liu D, Wang H. MnO 2-decorated N-doped carbon nanotube with boosted activity for low-temperature oxidation of formaldehyde. JOURNAL OF HAZARDOUS MATERIALS 2020; 396:122750. [PMID: 32339880 DOI: 10.1016/j.jhazmat.2020.122750] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/11/2020] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
Low-temperature oxidative degradation of formaldehyde (HCHO) using non-noble metal catalysts is challenging. Herein, novel manganese dioxide (MnO2)/N-doped carbon nanotubes (NCNT) composites were prepared with varying MnO2 content. The surface properties and morphologies were analyzed using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). Comparing with MnO2/carbon nanotubes (CNTs) catalyst, the 40% MnO2/NCNT exhibited much better activity and selectivity for HCHO oxidation, mineralizing 95% of HCHO (at 100 ppm) into CO2 at 30 °C at a gas hourly space velocity (GHSV) of 30,000 mL h-1 g-1. Density functional theory (DFT) calculation was used to analyze the difference in the catalytic activity of MnO2 with CNTs and NCNT carrier. It was confirmed that the oxygen on NCNT was more active than CNTs, which facilitated the regeneration of MnO2. This resulted in remarkably boosted activity for HCHO oxidation. The present work thus exploited an inexpensive approach to enhance the catalytic activity of transition metal oxides via depositing them on a suitable support.
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Ren C, Yan Y, Sun B, Gu B, Chou TW. Wet-spinning assembly and in situ electrodeposition of carbon nanotube-based composite fibers for high energy density wire-shaped asymmetric supercapacitor. J Colloid Interface Sci 2020; 569:298-306. [PMID: 32120137 DOI: 10.1016/j.jcis.2020.02.092] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/13/2020] [Accepted: 02/23/2020] [Indexed: 10/24/2022]
Abstract
Wire-shaped supercapacitors (WSC) have attracted tremendous attention for powering portable electronic devices. However, previously reported WSC suffered from a complicated fabrication process and high cost. The objective of this study is to develop a facile and scalable process for the fabrication of high energy density WSC. We coupled the wet-spinning assembly with an in situ electrodeposition technique to prepare carbon nanotube (CNT)-based composite fibers. The charge balance between the electrodes was realized by controlling the deposition time of the pseudocapacitive materials. A wire-shaped asymmetric supercapacitor (WASC) was fabricated by twisting MnO2/CNT fiber cathode and PPy/CNT fiber anode with LiCl/PVA electrolyte. The flexible MnO2/CNT//PPy/CNT WASC operated in a broadened voltage range of 0-1.8 V exhibited a high capacitance of 17.5F cm-3 (10.7F g-1). In addition, it delivered a maximum energy and power densities of 7.88 mWh cm-3 (4.82 Wh kg-1) and 2.26 W cm-3 (1382 W kg-1), respectively. The WASC device demonstrated satisfactory cycling stability with 86% capacitance retention, and its Coulombic efficiency remained at 96% after 5000 charge-discharge cycles. The contributions of the diffusion-controlled insertion and the surface capacitive effect were theoretically quantified to investigate the energy storage mechanism. The fabrication approaches hold potential for the construction of cost-effective and high-performance WSC.
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Li X, Ma J, Zhang C, Zhang R, He H. Detrimental role of residual surface acid ions on ozone decomposition over Ce-modified γ-MnO 2 under humid conditions. J Environ Sci (China) 2020; 91:43-53. [PMID: 32172981 DOI: 10.1016/j.jes.2019.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 11/28/2019] [Accepted: 12/02/2019] [Indexed: 06/10/2023]
Abstract
In the study, the catalyst precursors of Ce-modified γ-MnO2 were washed with deionized water until the pH value of the supernatant was 1, 2, 4 and 7, and the obtained catalysts were named accordingly. Under space velocity of 300,000 hr-1, the ozone conversion over the pH = 7 catalyst under dry conditions and relative humidity of 65% over a period of 6 hr was 100% and 96%, respectively. However, the ozone decomposition activity of the pH = 2 and 4 catalysts distinctly decreased under relative humidity of 65% compared to that under dry conditions. Detailed physical and chemical characterization demonstrated that the residual sulfate ions on the pH = 2 and 4 catalysts decreased their hydrophobicity and then restrained humid ozone decomposition activity. The pH = 2 and 4 catalysts had inferior resistance to high space velocity under dry conditions, because the residual sulfate ion on their surface reduced their adsorption capacity for ozone molecules and increased their apparent activation energies, which was proved by temperature programmed desorption of O2 and kinetic experiments. Long-term activity testing, X-ray photoelectron spectroscopy and density functional theory calculations revealed that there were two kinds of oxygen vacancies on the manganese dioxide catalysts, one of which more easily adsorbed oxygen species and then became deactivated. This study revealed the detrimental effect of surface acid ions on the activity of catalysts under humid and dry atmospheres, and provided guidance for the development of highly efficient catalysts for ozone decomposition.
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