# Fileset

[Supporting Information.pdf](https://mdr.nims.go.jp/filesets/1d474cba-d8a2-461a-9def-befd4720c68c/download)

## Creator

[Nobuyuki Sakai](https://orcid.org/0000-0002-9395-6751), Katsutoshi Fukuda, [Renzhi Ma](https://orcid.org/0000-0001-7126-2006), Takayoshi Sasaki

## Rights

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Synthesis and Substitution Chemistry of Redox-Active Manganese/Cobalt Oxide Nanosheets, copyright © 2018 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.chemmater.7b04068[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[Synthesis and Substitution Chemistry of Redox-Active Manganese/Cobalt Oxide Nanosheets](https://mdr.nims.go.jp/datasets/8de4a50c-6ffb-4ecb-8a66-b838d89e8c64)

## Fulltext

S1 Supporting Information  Synthesis and Substitution Chemistry of Redox-Active Manganese/Cobalt Oxide Nanosheets  Nobuyuki Sakai,*,† Katsutoshi Fukuda,‡ Renzhi Ma,† and Takayoshi Sasaki*,†  † International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan. ‡ Office of Society-Academia Collaboration for Innovation, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan. * Corresponding author: (N.S.) sakai.nobuyuki@nims.go.jp * Corresponding author: (T.S.) sasaki.takayoshi@nims.go.jp   Table S1. Refinement data for XRD patterns of Na-Mn1−xCoxO2.        S2 Table S2. Valence, Ionic Radii, and Interatomic Distance for the Obtained Layered Crystals of Na-Mn1−xCoxO2.   a Valence of Co, ZCo, is assumed to be 3 on the basis of XANES data. b Values obtained from Zmean = x×ZCo + (1−x)×ZMn. c Mean ionic radius of Mn4+ and Mn3+ (high spin state), rMn, is calculated as rMn = (ZMn−3)×rMn(IV) + (4−ZMn)×rMn(III, HS). rMn(IV) = 0.53 Å and rMn(III, HS) = 0.645 Å.S1 d Mean ionic radius of Mn and Co, rmean, is calculated as rmean = x×rCo(III, LS) + (1−x)×rMn. rCo(III, LS) = 0.545 Å.S1 e Interatomic distance between metal ions and oxygen, RM−O, is obtained as RM−O = rmean + rO. rO = 1.36 Å.S1 f Values from Fig. 2. g Lattice constant a for K0.45MnO2 from ref. S2.   Table S3. Refinement data for XRD patterns of H-Mn1−xCoxO2.       S3 Table S4. Valence, Ionic Radii, and Interatomic Distance for the Obtained Layered Crystals of H-Mn1−xCoxO2.   a Valence of Co, ZCo, is assumed to be 3 on the basis of XANES data. b Values obtained from Zmean=x×ZCo+(1−x)×ZMn. c Mean ionic radius of Mn4+ and Mn3+ (high spin state), rMn, is calculated as rMn=(ZMn−3)×rMn(IV)+(4−ZMn)×rMn(III, HS). rMn(IV) = 0.53 Å and rMn(III, HS) = 0.645 Å.S1 d Mean ionic radius of Mn and Co, rmean, is calculated as rmean=x×rCo(III, LS)+(1−x)×rMn. rCo(III, LS) = 0.545 Å.S1 e Interatomic distance between metal ions and oxygen, RM−O, is obtained as RM−O=rmean+rO. rO = 1.36 Å.S1 f Values from Fig. 2. g Lattice constant a for H0.13MnO2 from ref. S3.   Table S5. Comparison of the values of Mn valence after protonation deduced from the dissolved amount of Co2+ ions and the investigation by titration and XANES.   a Values from Table S1. b Values from Fig. S4. c Valence for Mn deduced from the dissolved amount of Co2+ and ZMn before protonation on the assumption that the same amount of Mn2+ is also dissolved as Co2+, and Co4+ takes one electron from Mn3+ forming of Co3+ and Mn4+. d Values from Table S2, which is estimated from the titration and XANES studies.    S4 Table S6. Atomic concentration of Mn1−xCoxO2 nanosheets revealed by XPS survey spectra.     Figure S1. Mean valence of metal ions in the Na-Mn1−xCoxO2 (open symbols) and H-Mn1−xCoxO2 (closed symbols) powders estimated by chemical titration (circles) or Na content revealed by ICP measurement (triangles).           S5  Figure S2. Calculated lattice constant a of (a) Na-Mn1−xCoxO2 and (b) H-Mn1−xCoxO2 on the basis of the bond length of (Mn/Co)−O estimated from Mn/Co ratio, ZMn, and ionic radii of O2−, Mn4+, Mn3+ and Co3+ in high spin state (HS) or low spin state (LS). The ratio of the lattice constant a to the bond length is assumed to be the same as that for (a) K0.45MnO2 (Table S1) or (b) H0.13MnO2 (Table S2). The plots of red in color are well consistent to the experimental data, suggesting that it is reasonable to assume high spin Mn3+ and low spin Co3+ ions in both samples, Na-Mn1−xCoxO2 and H-Mn1−xCoxO2. The plots of blue, green, and purple in color are obtained by considering other combinations including Mn3+(HS)-Co3+(HS), Mn3+(LS)-Co3+(HS), and Mn3+(LS)-Co3+(LS). The radii of Mn3+(LS) and Co3+(HS) are 0.58 Å and 0.61 Å, respectively.S1    Figure S3. Typical SEM images of (a) Na-Mn1−xCoxO2 and (b) H-Mn1−xCoxO2 (x = 0.2) powders.    S6  Figure S4. UV−vis absorption spectra of used 0.1 M HCl solution collected after the protonation process of Na-Mn1−xCoxO2 (x = 0.2, red line) and fresh 0.1 M HCl containing 0.01 M CoCl2 (green line). On the basis of absorption peak at 510 nm (e = 5.1 mol−1 dm3 cm−1 for Co2+), it was estimated that 11.6 mol% of Co in the Na-Mn1−xCoxO2 (x = 0.2) was dissolved as Co2+ ions. In a similar way, it was found that 7.5 mol%, 2.6 mol%, 0.6 mol% of Co in the Na-Mn1−xCoxO2 (x = 0.3, 0.4, 0.5) was dissolved during the protonation process.    Figure S5. XPS spectra of nanosheets deposited on Si substrates coated with poly(diallyldimethylammonium) ions. The spectra were calibrated relative to the C 1s binding energy at 285.0 eV.   S7   Figure S6. AFM images of Mn1−xCoxO2 nanosheets deposited on flat ITO substrates (Kuramoto Co., Ltd.) pre-coated with PEI: (a) x = 0.2, (b) x = 0.3, (c) x = 0.4, (d) x = 0.5.    Figure S7. Changes of cyclic voltammogram of monolayer films of Mn1−xCoxO2 nanosheet electrodes as a function of number of cycles in a propylene carbonate solution containing 0.1 mol dm−3 LiClO4 at a sweep rate of 50 mV s−1: (a) x = 0.2, (b) x = 0.3, (c) x = 0.4, (d) x = 0.5.              S8  Figure S8. In-plane XRD patterns of monolayer films of Mn1−xCoxO2 (x = 0.2, 0.3, 0.4, 0.5) nanosheet electrodes after 200 cycles of potential sweeps. The arrow indicates the peak corresponding to 10 reflection of the nanosheets. All other peaks are ascribable to ITO substrates.   References (S1) Shannon, R. D. Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides. Acta Cryst. A 1976, 32, 751−767. (S2) Omomo, Y.; Sasaki, T.; Wang, L. Z.; Watanabe, M. Redoxable Nanosheet Crystallites of MnO2 Derived via Delamination of a Layered Manganese Oxide. J. Am. Chem. Soc. 2003, 125, 3568−3575. (S3) Fukuda, K.; Nakai, I.; Ebina, Y.; Tanaka, M.; Mori, T.; Sasaki, T. Structure Analysis of Exfoliated Unilamellar Crystallites of Manganese Oxide Nanosheets. J. Phys. Chem. B 2006, 110, 17070−17075.