Topochemical Synthesis of Co鈭扚e Layered Double Hydroxides at Varied Fe/Co Ratios: Unique Intercalation of Triiodide and Its Profound Effect
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- 作者：Renzhi Ma ; Jianbo Liang ; Kazunori Takada ; Takayoshi Sasaki
- 刊名：Journal of the American Chemical Society
- 出版年：2011
- 出版时间：January 26, 2011
- 年：2011
- 卷：133
- 期：3
- 页码：613-620
- 全文大小：451K
- 年卷期：v.133,no.3(January 26, 2011)
- ISSN：1520-5126
文摘
Co鈭扚e layered double hydroxides at different Fe/Co ratios were synthesized from brucite-like Co2+1鈭?i>xFe2+x(OH)2 (0 鈮?x 鈮?1/3) via oxidative intercalation reaction using an excess amount of iodine as the oxidizing agent. A new redoxable species: triiodide (I3鈭?/sup>), promoted the formation of single-phase Co鈭扚e LDHs. The results point to a general principle that LDHs with a characteristic ratio of total trivalent and divalent cations (M3+/M2+) at 1/2 may be the most stable in the oxidative intercalation procedure. At low Fe content, e.g., starting from Co2+1鈭?i>xFe2+x(OH)2 (x < 1/3), partial oxidation of Co2+ to Co3+ takes place to reach the M3+/M2+ threshold of 1/2 in as-transformed Co2+2/3鈭?Co3+1/3鈭?i>x鈭扚e3+x) LDHs. Also discovered was the cointercalation of triiodide and iodide into the interlayer gallery of as-transformed LDH phase, which profoundly impacted the relative intensity ratio of basal Bragg peaks as a consequence of the significant X-ray scattering power of triiodide. In combination with XRD simulation, the LDH structure model was constructed by considering both the host layer composition/charge and the arrangement of interlayer triiodide/iodide. The work provides a clear understanding of the thermodynamic and kinetic factors associated with the oxidative intercalation reaction and is helpful in elucidating the formation of LDH structure in general.