Small
·
2022
·Vol. 18
·期 49
·2204484
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IF 15.153
Yibo Chen,Zhi-Han Zuo,Zhao-Qing Liu,Yadong Yin
Drop-casting manganese oxide (MnO 2 ) hollow nanospheres synthesized via a simple surface-initiated redox route produces thin films exhibiting angle-independent structural colors. The colors can rapidly change in response to high-humidity dynamic water vapor (relative humidity > 90%) with excellent reversibility. When the film is triggered by dynamic water vapor with a relative humidity of ≈100%, the color changes with an optimal wavelength redshift of ≈60 nm at ≈600 ms while there is no shift under static water vapor. The unique selective response originates from the nanoscale porosity formed in the shells by randomly stacked MnO 2 nanosheets, which enhances the capillary condensation of dynamic water vapor and promotes the change of their effective refractive index for rapid color switching. The repeated color-switching tests over 100 times confirm the durability and reversibility of the MnO 2 film. The potential of these films for applications in anti-counterfeiting and information encryption is further demonstrated by reversible encoding and decoding initiated exclusively by exposure to human breath.
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Membranes
·
2022
·Vol. 12
·期 11
·1044
·
IF 4.562
Tingting Liu,Lei Chen,Ling Chen,Guoxing Tian,Mingtong Ji,Shuai Zhou
In this paper,δ-MnO2with layered structure was prepared by a facile liquid phase method, and exfoliated MnO2nanosheet (e-MnO2) was obtained by ultrasonic exfoliation, whose surface was negatively charged. Then, positive charges were grafted on the surface of MnO2nanosheets with a polycation electrolyte of polydiallyl dimethylammonium chloride (PDDA) in different concentrations. A series of e-MnO2@reduced graphene oxide (rGO) composites were obtained by electrostatic self-assembly combined with hydrothermal chemical reduction. When PDDA was adjusted to 0.75 g/L, the thickness of e-MnO2was ~1.2 nm, and the nanosheets were uniformly adsorbed on the surface of graphene, which shows layer-by-layer morphology with a specific surface area of ~154 m2/g. On account of the unique heterostructure, the composite exhibits good electrochemical performance as supercapacitor electrodes. The specific capacitance of e-MnO2-0.75@rGO can reach 456 F/g at a current density of 1 A/g in KOH electrolyte, which still remains 201 F/g at 10 A/g. In addition, the capacitance retention is 98.7% after 10000 charge-discharge cycles at 20 A/g. Furthermore, an asymmetric supercapacitor (ASC) device of e-MnO2-0.75@rGO//graphene hydrogel (GH) was assembled, of which the specific capacitance achieves 94 F/g (1 A/g) and the cycle stability is excellent, with a retention rate of 99.3% over 10000 cycles (20 A/g).Keywords:MnO2;reduced graphene oxide (rGO);layer-by-layer;supercapacitor
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ACS Applied Materials & Interfaces
·
2022
·
IF 10.383
Qinghe Liu,Sen Wang,Fei Han,Shupei Lv,Zairong Yan,Yunfei Xi,Jing Ouyang
Highly efficient three-dimensional (3D) kaolinite/MnO2–CuO (KM@CuO–NO3) catalysts were synthesized by a mild biomimetic strategy. Kaolinite flakes were uniformly wrapped by ultrathin tremelliform MnO2 nanosheets with thicknesses of around 1.0–1.5 nm. Si–O and Al–O groups in kaolinite hosted MnO2 nanosheets to generate a robust composite structure. The ultrathin MnO2 lamellar structure exhibited excellent stability even after calcination above 350 °C. Kaolinite/MnO2 exhibited abundant edges, sharp corners, and interconnected diffusion channels, which are superior to the common stacked structure. Open channels guaranteed fast transportation and migration of CO and O2 during CO oxidation. The synthesized KM@CuO–NO3 achieved a 90% CO conversion efficiency at a relatively low temperature (110 °C). Furthermore, the abundant oxygen vacancies on KM@CuO-NO3 assisted the adsorption and activation of oxygen species and thus enhanced the oxygen mobility and reactivity in the catalytic process. The mechanism results suggest that CuO introduced to the catalyst not only acted as CO active sites but also weakened the Mn–O bond, subsequently improved the mobilities of the oxygen species, which was found to contribute to its high activity for CO oxidation. This study provides new conceptual insights into rationally regulating structural assembly between transition metal oxides and natural minerals for high-performance catalysis reactions.
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Journal of Water Process Engineering
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2022
·
IF 7.34
Xingyu Fang,Ying Wu,Lijie Xu,Lu Gan
In this study, a series of coconut shell biochars (CSB) with different pyrolysis temperature were prepared and incorporated with α-MnO 2 for bisphenol A (BPA) degradation in water through activating peroxymonosulfate (PMS). The results showed that with the assistance of CSB, α-MnO 2 /CSB exhibited superior catalytic activity over pristine α-MnO 2 , in which CSB played multiple roles in the composite. Basically, CSB could effectively improve the dispersion and expose more active sites of α-MnO 2 . Besides, CSB could build solid interactions with α-MnO 2 and boost the electron transferring rate between catalyst, PMS and BPA. Moreover, α-MnO 2 and CSB were both enrolled in the generation of radical and non-radical species for BPA degradation. Having multiple active species, the α-MnO 2 /CSB composite could maintain high catalytic performance under a wide pH range with good reusability and adaptability. The existence of both radical and non-radical pathways was further verified through identifying the BPA degradation intermediates. This study provides a new insight for the design of novel composite catalyst for water decontamination using biochar as a multifunctional participant.
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SOLAR ENERGY
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2022
·
IF 7.188
Bo Ge,Mingyang Li,Heyuan Li,Yuchao Li,Guina Ren,Wei Li
Environmental governance and clean water production are the challenges that human face. In this paper, the device composed of superhydrophobic layer, hydrophilic channel and photothermal conversion layer was fabricated. The superhydrophobic layer has a contact angle of 162°, which not only ensures the floating of the device, but also has the ability to selectively absorb non-water-soluble pollutants. In addition, the surface-loaded Bi 2 MoO 6 /Bi 2 O 3 photocatalyst can also degrade the water-soluble pollutants. After 4 cycles of photodegradation, the degradation efficiency was 92.6 %, demonstrating a stable degradation stability. The optimal content of MnO 2 (60 mg) was demonstrated by steam production rate experiments. The mechanical stability of superhydrophobic fabric, chemical stability of the MnO 2 , and photothermal stability were demonstrated. The assembled multifunctional devices can be used both for environmental treatment and for clean water production.
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MOLECULES
·
2022
·Vol. 27
·期 15
·4863
·
IF 4.927
Shun Li,Zuquan Zheng,Zhicheng Zhao,Youling Wang,Yao Yao,Yong Liu,Jianming Zhang,Zuotai Zhang
CeO2nanoparticle-loaded MnO2nanoflowers, prepared by a hydrothermal method followed by an adsorption-calcination technique, were utilized for selective catalytic reduction (SCR) of NOxwith NH3at low temperatures. The effects of Ce/Mn ratio and thermal calcination temperature on the NH3–SCR activity of the CeO2-MnO2nanocomposites were studied comprehensively. The as-prepared CeO2-MnO2catalysts show high NOxreduction efficiency in the temperature range of 150–300 °C, with a complete NOxconversion at 200 °C for the optimal sample. The excellent NH3–SCR performance could be ascribed to high surface area, intimate contact, and strong synergistic interaction between CeO2nanoparticles and MnO2nanoflowers of the well-designed composite catalyst. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) characterizations evidence that the SCR reaction on the surface of the CeO2-MnO2nanocomposites mainly follows the Langmuir–Hinshelwood (L-H) mechanism. Our work provides useful guidance for the development of composite oxide-based low temperature NH3–SCR catalysts.Keywords:Mn-Ce mixed oxide;ion-adsorption;selective catalytic reduction;NOxconversion
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SEPARATION AND PURIFICATION TECHNOLOGY
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2022
·
IF 9.136
Yalong Duan,Jiang Yu,Ruxia Zhang,Pengfei Han,Ping Ren,Min Liu,Ngie Hing Wong,Jaka Sunarso
Membrane filtration integrated with micro-nano bubbles (MNBs) is an attractive technology for treating dye wastewater given its efficiency and environmental compatibility. However, the amount of ·OH generated during the disintegration of MNBs is insufficient in practical applications. This work presents the characterisation of a modified Al 2 O 3 ceramic membrane (CM) with the MnO 2 nanosheet (MnO 2 /Al 2 O 3 CM), which provides dual functions of membrane filtration and MNB catalysis. Here, a novel MNB catalytic membrane reactor (MNB-CMR) was constructed by applying the modified MnO 2 /Al 2 O 3 CM for treating the simulated dye wastewater, i.e., methylene blue (MB). The MB degradation showed that the MNB-CMR improved 17% decolorization rate and 20% total organic carbon removal rate compared to the integrated MNB process with the non-modified CM. The MNB-CMR exhibited excellent catalytic performance and fouling resistance. Besides, the effects of MNB-CMR operational parameters such as the initial methylene blue (MB) concentration, reaction temperature, solution flux, and solution pH on the MB degradation performance were investigated. Based on the scavenging experiments of reactive oxygen species (ROS), the reaction of singlet oxygen ( 1 O 2 ) or hydroxyl radicals (·OH) was elucidated as the primary ROS responsible for the oxidation of MB in the MNB-CMR. In addition, the XPS results showed that the redox couple of Mn(IV)/Mn(III) on the surface of the MnO 2 /Al 2 O 3 CM was responsible for MNB catalysis. Finally, we proposed a possible degradation pathway of MB. This work shows an attractive alternative wastewater treatment process to relieve membrane fouling and enhance MNB catalysis concurrently.
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Nanomaterials
·
2022
·Vol. 12
·期 9
·1429
·
IF 5.719
Shuo Liu,Peng Zhang,Yuming Miao,Chenmin Li,Yu-e Shi,Jinhua Liu,Yun-kai Lv,Zhenguang Wang
Selective and sensitive identification of paraoxon residue in agricultural products is greatly significant for food safety but remains a challenging task. Herein, a detection platform was developed by integrating Cu nanoclusters (Cu NCs) with MnO2nanosheets, where the fluorescence of Cu NCs was effectively quenched. Upon introducing butyrylcholinesterase and butyrylcholine into the system, their hydrolysate, thiocholine, leads to the decomposition of the platform through a reaction between the MnO2nanosheets and thiol groups on thiocholine. The electron-rich groups on thiocholine can further promote the fluorescence intensity of Cu NCs through host–guest interactions. Adding paraoxon results in the failure of fluorescence recovery and further promotion, which could be utilized for the quantitative detection of paraoxon, and a limit of detection as low as 0.22 ng/mL can be achieved. The detection platform shows strong tolerance to common interference species, which endows its applications for the detection of paraoxon in vegetables and fruit. These presented results not only open a new door for the functionalization of metal nanoclusters but also offer an inspiring strategy for analytic techniques in nanomedicine and environmental science.Keywords:organophosphorus pesticides;fluorometry assay;metal nanoclusters;MnO2nanosheets;fluorescence quenching
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
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2022
·
IF 4.831
Yawen Lian,Xiang Yuan,Yandan Wang,Lin Wei
In this study, a highly sensitive colorimetric assay has been constructed for the determination of xanthine oxidase (XOD) activity by the [email protected] 2 core-shell nanoparticles as probe. In the presence of XOD, xanthine can be oxidized to produce H 2 O 2 , which makes the MnO 2 shell fallen off. With the single particle detection (SPD) based dark field microscopy (DFM), the scattering color of [email protected] 2 NP probe shows obvious change before and after etching process. At the single particle level, noticeable color change of the single probe can be easily detected in the existence of trace XOD. This SPD-based colorimetric strategy displays broad linear dynamic range (0.02–4 mU/mL) and low detection limit of 7.82 μU/mL, which is more sensitive than the results from ensemble sample measurement. In addition, we tested the inhibitory effect of quercetin on the activity of XOD and obtained good inhibition effect. As a consequence, this SPD-based colorimetric strategy provides new perception for the ultrasensitive detection of molecules in complex system.
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JOURNAL OF MEMBRANE SCIENCE
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2022
·
IF 10.53
Xuesong Ye,Jun Nan,Zhencheng Ge,Qiliang Xiao,Bohan Liu,Yujie Men,Jinyong Liu
Low-pressure ultrafiltration membrane (LPM) is an ideal technology for decentralized water supply. However, the applicability for removing ferrous iron (Fe 2+ ), manganese (Mn 2+ ), and ammonia (NH 4 + ) in the source water and related mechanisms remained unknown. To fill this major knowledge gap, we systematically compared the pristine (pr-LPM) and MnO 2 -preloaded membrane (Mn-LPM). Mn-LPM allowed higher water flux while enhancing the removal of Fe 2+ , Mn 2+ , and NH 4 + . The removal efficiency of Mn 2+ immediately reached 99.6% on the first day. The preloading of MnO 2 also enhanced the removal capacity of NH 4 + . A series of instrument characterizations suggest that a higher NH 4 + concentration resulted in a thicker bio-cake layer, correlating to the higher pollutant removal efficiency and the decrease in the stable flux. Under high NH 4 + concentrations, Anaerobic Ammonia Oxidation likely contributes to NH 4 + removal. These findings significantly improve the understanding and help the design of LPM systems for cost-effective decentralized water supply in remote areas.
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Energy Storage Materials
·
2022
·
IF 20.831
Chong Bai,Kang Ji,Shuxuan Feng,Jiaxue Zhang,Desheng Kong
Stretchable batteries are indispensable energy storage devices to power emerging wearable electronics in soft form factors. In contrast to commonly employed engineering approaches to mitigate strains through structural design, the intrinsically stretchable devices naturally exhibit skin-like mechanical deformability by using all compliant building components. Currently, the intrinsically stretchable battery often shows a significant trade-off between electrochemical performances and mechanical deformability. Here, we introduce a low-cost and scalable approach to create an intrinsically stretchable aqueous battery featuring the deployment of state-of-art battery materials and binders. The compliant current collector, in the form of a bilayer silver nanowire/carbon nanotube nanocomposites, demonstrates excellent mechanical stretchability and electrochemical stability. The microcracked electrode layer retains stable charge transport and excellent electrochemical activity under large mechanical deformations through firm attachment to the bilayer current collector. A stretchable Zn-MnO 2 cell in a sandwiched configuration is assembled exhibiting high specific capacity (>200 mAh g −1 at 100 mA g −1 ), excellent capacity retention of ∼90% over 100 cycles, large stretchability up to 100% strain, and durability against repetitive mechanical deformations. The practical suitability is demonstrated by a stand-alone electronic system conformably mounted on the wrist, in which an LED array is powered by a pair of stretchable Zn-MnO 2 batteries.
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Energy Storage Materials
·
2022
·
IF 20.831
Yajun Zhao,Pengjun Zhang,Jinrui Liang,Xiaoyu Xia,Longtao Ren,Li Song,Wen Liu,Xiaoming Sun
Manganese-based oxides are considered potential cathode materials for rechargeable aqueous zinc ion batteries (RAZIBs). However, structural instability and sluggish reaction kinetics are major limitations restricting their available capacity and cycle stability. Herein, sulfur doped MnO 2 (S-MnO 2 ) nanosheets is proposed as a high performance cathode for Zn-ion batteries, featuring large discharge capacity, high rate performance and long cycle life. Electrochemical measurements show a specific discharge capacity of 324 mAh g −1 at a current density of 200 mA g −1 and 205 mAh g −1 at a current density of 2000 mA g −1 , which is 1.1 and 5.8 folds higher than that of pristine MnO 2 . The ex-situ X ray diffraction/absorption, electrochemical analysis and theoretical studies reveal that the doped sulfur atoms in oxygen sites with lower electronegativity can improve intrinsic electronic conductivity of MnO 2 and weaken the electrostatic interactions with multivalent Zn 2+ cations, thus accelerating reaction kinetics. Moreover, sulfur doping induced amorphous surface with rich oxygen defects contributing to extra Zn storage sites with pseudocapacitve behavior. This study shines a new light on the anionic doping strategy in metal oxides for Zn ions storage and can be expanded to other cathode materials design for energy storage applications .
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