Structural Distortion in MnO2 Nanosheets and Its Suppression by Cobalt Substitution
نویسندگان
چکیده
Co-Mn oxide nanosheets with the chemical composition H0.23Co0.23Mn0.77O₂ (C23M77NS) and MnO₂ nanosheets (M100NS) were prepared by exfoliation of layer-structured oxides via chemical processing in an aqueous medium. The optical properties of C23M77NS and M100NS were compared using UV-Vis spectroscopy, and the valence states of Mn and Co and local structures around them were examined using X-ray absorption spectroscopy. M100NS with an average Mn valence of 3.6 exhibits large structural distortion, whereas C23M77NS with an average Mn valence of 4.0 does not exhibit structural distortion. Spontaneous oxidization of Mn occurs during ion-exchange and/or exfoliation into nanosheets. These results have originated the hypothesis that structural distortion determines the valence state of Mn in compounds with CdI₂-type-structured MnO₂ layers.
منابع مشابه
The Effect of Zn- Cr Substitution on the Structural and Magnetic Properties of Cobalt Ferrite Nanoparticles
In this investigation, the structural and magnetic properties of Cr and Zn substituted Co ferrite with the general formula Co1-xZnxFe2-xCrxO4 (x= 0.1, 0.3, 0.5, 0.7) as prepared by sol- gel method were studied. The structural, morphological and magnetic properties of the samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM)...
متن کاملPhotoelectrochemical Behavior of the MnO2 Nanosheet Electrodes
We recently synthesized a new modification of nanosized oxides such as titania [1] and manganese oxide [2] by delaminating precursor layered crystals into their elementary layers. The obtained materials have been named nanosheets on the basis of their two-dimensional morphology, as depicted in Fig. 1. The crystallite has an extremely small thickness less than 1 nm and a lateral size ranging fro...
متن کاملDesign of a Fluorescent Sensor Based on the Polydopamine Nanoparticles for Detection of Gallic Acid
Background: Gallic acid (GA) is one of the polyphenolic compounds with antioxidant, antimicrobial and radical scavenging activities, which plays a main role in human health against cancer and cardiovascular diseases. GA concentration can be quantitatively measured in food, medicinal plants and body fluids. Materials and Methods: In this study, MnO2 nanosheets were prepared by reducing potassium...
متن کاملIn-situ generation of gold nanoparticles on MnO2 nanosheets for the enhanced oxidative degradation of basic dye (Methylene Blue).
In this work, the gold nanoparticles (Au-NPs) were in-situ generated on the surface of MnO2 nanosheets to form MnO2/Au-NPs nanocomposite in a simple and cost-effective way. Multiple experiments were carried out to optimize the oxidation of basic dye (Methylene Blue (MB)), including the molar ratio of MnO2 to chloroauric acid (HAuCl4), the pH of the solution and the effect of initial material. U...
متن کاملReversible phase transformation of MnO2 nanosheets in an electrochemical capacitor investigated by in situ Raman spectroscopy.
The reversible phase transformation is reported from hexagonal to monoclinic structure responding to the intercalation/deintercalation of Na(+) between MnO(2) nanosheets upon potential cycling in aqueous electrolyte via an in situ Raman technique. This structural evolution will influence the Na(+) diffusion process in MnO(2) nanosheets and cause phase retention during the self-discharge process.
متن کامل