Structure of synthetic Na-birnessite: Evidence for a triclinic one-layer unit cell

Lanson, Bruno; Drits, Victor A.; Feng, Qi; Manceau, Alain

doi:10.2138/am-2002-11-1215

Cited by 165 publications

(173 citation statements)

References 37 publications

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“…Na-birnessite was reported to be triclinic by Lanson et al [17,18]. Its slight deviation from the hexagonal symmetry originates from the elongation along [100] of the Jahn-Teller distorted Mn 3+ [17,18]. Close examination of Fig.…”

Section: Nano Researchmentioning

confidence: 99%

“…The birnessite nanosheets were initially produced by dissolution of Mn 2 O 3 powder in concentrated NaOH followed by recrystallization with concomitant intercalation of Na + and H 2 O. Conversion from the birnessite to various 1-D tunnel structures has been studied for a long time, and is believed to start with a disproportionation reaction of neighboring Mn 3+ ions in the manganese oxide layers into Mn 4+ and Mn 2+ ions [15,17,19]. The Mn 2+ ions migrate into the interlayer galleries, undergo oxidation to Mn 3+ by oxygen in the autoclave and assist the formation of corner-sharing MnO 6 octahedra.…”

Section: Nano Researchmentioning

confidence: 99%

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Formation of Na0.44MnO2 nanowires via stress-induced splitting of birnessite nanosheets

2009

Nano Res.

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High aspect ratio Na 0.44 MnO 2 nanowires with a complex one-dimensional (1 D) tunnel structure have been synthesized. We found that the reaction went through layered birnessite nanosheet intermediates, and that their conversion to the fi nal product involved splitting of the nanosheets into nanowires. Based on our observations, a stress-induced splitting mechanism for conversion of birnessite nanosheets to Na 0.44 MnO 2 nanowires is proposed. The fi nal and intermediate phases show topotaxy with 001 f // 020 b or 110 b where f represents the fi nal Na 0.44 MnO 2 phase and b the intermediate birnessite phase. As a result of their high surface areas, the nanowires are effi cient catalysts for the oxidation of pinacyanol chloride dye. KEYWORDSBirnessite, manganese oxide, nanowire, nanosheet, stress, conversion Manganese oxide nanowires with layered or tunnel structures are attractive for applications in batteries, separation and catalysis due to their open-framework structures and interesting redox properties [1 9]. There have been several studies of their synthesis in the literature: for example, MnO 2 nanorods were synthesized through a carefully controlled hydrothermal reaction by oxidizing MnSO 4 with (NH 4 ) 2 S 2 O 8 or KMnO 4 [10,11]. Nanowires with cryptomelane [12], romanechite [6,13], and RUB 7 [13 15] structures have also been produced in aqueous solution. Most of these approaches involved a birnessite phase observed as an intermediate [11] or used as precursor [6, 13 15]. Birnessite possesses a layered structure formed of edge-sharing MnO 6 octahedra with Na + cations and H 2 O molecules filling the interlayer space ( Fig. 1 (a)). Conversion of birnessite has been used as a general strategy to obtain a variety of tunnel structures [1]. However, the underlying mechanism remains unclear. Recently, the curling or rolling up of birnessite layers as a result of weakened interlayer interactions during hydrothermal treatment was proposed [11]. While this mechanism can explain tube formation from exfoliated molecular sheets, it cannot rationalize the formation of non-hollow manganese oxide nanowires.Herein we report a stress-induced splitting mechanism that transforms birnessite nanosheets into Na 0.44 MnO 2 nanowires. Na 0.44 MnO 2 has a complex tunnel structure. It consists of columns of edge-sharing MnO 5 square pyramids and sheets of edge-sharing MnO 6 octahedra extending parallel to the c-axis (Fig. 1 (b)). They are connected by cornerNano Res (2009) sharing to form two types of tunnels: large S-shaped, and six-sided tunnels, both occupied by Na + cations.In our study, Na 0.44 MnO 2 nanowires were synthesized by a hydrothermal method. Their X-ray diffraction (XRD) pattern shows diffraction peaks in good agreement with the standard pattern (PDF No. 27 0750), except for some variation in peak intensities due to nanowire orientation ( Fig. 2(a)). An scanning electron microscopy (SEM) image reveals that they are pure nanowires with average length over 10 μm and diameter smaller than 100 nm (Fig. 2(b)...

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Section: Nano Researchmentioning

confidence: 99%

Section: Nano Researchmentioning

confidence: 99%

Formation of Na0.44MnO2 nanowires via stress-induced splitting of birnessite nanosheets

2009

Nano Res.

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“…Clusters of atoms utilized in the analysis of Ni K-edge EXAFS spectra were based on the crystal structure of hexagonal birnessite published by Lanson et al (2002). An amplitude reduction factor (S 0 2 ) of 0.96 was determined by fitting the Ni-O shell of NiCl 2 (aq) and Ni(II)EDTA(aq) EXAFS spectra.…”

Section: Exafs Spectroscopymentioning

confidence: 99%

Mechanisms of nickel sorption by a bacteriogenic birnessite

Peña

Kwon

Refson

et al. 2010

Geochimica et Cosmochimica Acta

119

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Bacteriogenic birnessite nanoparticles have a large capacity to adsorb metal cations due to their high proportion of cation vacancy defects. In the current study, a synergistic experimental-computational approach was used to study the molecular-scale mechanisms of Ni sorption at varying loadings and at pH 6-8 using the hexagonal birnessite produced by Pseudomonas putida GB-1. We found that Ni is scavenged effectively by the biomass-

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“…Birnessites exhibit a rich variety of unit cell parameters, varying degrees of Mn(III) substitution at Mn(IV) layer sites, and varying Mn(IV) layer vacancy contents e.g., (Lanson et al, 2000(Lanson et al, , 2002aWebb et al, 2005b,c;Villalobos et al, 2006). This behavior suggests the need for a data analysis approach that can account for sample-to-sample differences in structural parameters within layered Mn oxides.…”

Section: Exafsmentioning

confidence: 99%

“…At values >0°, multiple scattering is attenuated as predicted by theory. The model also accounts for (b) splitting of the Mn-O shell into 4 short/2 long Mn-O bonds as is believed to occur in layer Mn oxides due to J-T distortion (Lanson et al, 2002a); (c) splitting of in-layer Mn-Mn distances due to J-T distortion of the first shell or to loss of hexagonal layer symmetry; (d) the presence of particle edge terminations layer and layer Mn(IV) site vacancies, believed to be present in biogenic and hexagonal layered Mn oxides (Villalobos et al, 2006), which linearly attenuate the intensity of all Mn shells (i.e. at 2.8, 4.8, and 5.7 Å ) by a similar factor (this behavior is different from rumpling of layers, which specifically attenuates the 5.7 Å shell but not those at 2.8 and 4.8 Å ); and (e) the presence of sorbed Mn(II), which has little to no extended local structure and hence dilutes the signal from the birnessite 2nd and higher shell features.…”

Section: Exafsmentioning

confidence: 99%

Structural characterization of terrestrial microbial Mn oxides from Pinal Creek, AZ

Bargar

Fuller

Marcus

et al. 2009

Geochimica et Cosmochimica Acta

110

106

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The microbial catalysis of Mn(II) oxidation is believed to be a dominant source of abundant sorption-and redox-active Mn oxides in marine, freshwater, and subsurface aquatic environments. In spite of their importance, environmental oxides of known biogenic origin have generally not been characterized in detail from a structural perspective. Hyporheic zone Mn oxide grain coatings at Pinal Creek, Arizona, a metals-contaminated stream, have been identified as being dominantly microbial in origin and are well studied from bulk chemistry and contaminant hydrology perspectives. This site thus presents an excellent opportunity to study the structures of terrestrial microbial Mn oxides in detail. XRD and EXAFS measurements performed in this study indicate that the hydrated Pinal Creek Mn oxide grain coatings are layer-type Mn oxides with dominantly hexagonal or pseudo-hexagonal layer symmetry. XRD and TEM measurements suggest the oxides to be nanoparticulate plates with average dimensions on the order of 11 nm thick Â 35 nm diameter, but with individual particles exhibiting thickness as small as a single layer and sheets as wide as 500 nm. The hydrated oxides exhibit a 10-Å basal-plane spacing and turbostratic disorder. EXAFS analyses suggest the oxides contain layer Mn(IV) site vacancy defects, and layer Mn(III) is inferred to be present, as deduced from Jahn-Teller distortion of the local structure. The physical geometry and structural details of the coatings suggest formation within microbial biofilms. The biogenic Mn oxides are stable with respect to transformation into thermodynamically more stable phases over a time scale of at least 5 months. The nanoparticulate layered structural motif, also observed in pure culture laboratory studies, appears to be characteristic of biogenic Mn oxides and may explain the common occurrence of this mineral habit in soils and sediments.

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Structure of synthetic Na-birnessite: Evidence for a triclinic one-layer unit cell

Cited by 165 publications

References 37 publications

Formation of Na0.44MnO2 nanowires via stress-induced splitting of birnessite nanosheets

Formation of Na0.44MnO2 nanowires via stress-induced splitting of birnessite nanosheets

Mechanisms of nickel sorption by a bacteriogenic birnessite

Structural characterization of terrestrial microbial Mn oxides from Pinal Creek, AZ

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