Synthesis of a Nanofibrous Manganese Oxide Octahedral Molecular Sieve with Co(NH3)63+ Complex Ions as a Template via a Reflux Method

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• 作者：Haojie Cui ; Xionghan Feng ; Wenfeng Tan ; Wei Zhao ; Ming Kuang Wang ; Tou Ming Tsao ; Fan Liu
• 刊名：Crystal Growth & Design
• 出版年：2010
• 出版时间：August 4, 2010
• 年：2010
• 卷：10
• 期：8
• 页码：3355-3362
• 全文大小：1060K
• 年卷期：v.10,no.8(August 4, 2010)
• ISSN：1528-7505

文摘

Todorokite-type manganese oxide octahedral molecular sieves (OMS-1) have been extensively studied due to their potential applications as materials. In this study, a nanofibrous todorokite-type, tunnel structure, manganese oxide molecular sieve material was successfully synthesized from a layered precursor with Co(NH₃)₆³⁺ complex ions as a template director by a refluxing method (namely, Co(N)-todorokite). X-ray photoelectron spectroscopy (XPS) indicates that complex ions are located in the tunnel of the Co(N)-todorokite in the form of [Co(NH₃)_x]³⁺ (4 < x < 6) ions, while keeping the trivalence of the cobalt ions. Scanning electron microscopic (SEM) and high resolution transmission electron microscopic (HRTEM) images reveal that this material has a fibrous morphology with a thickness of 20−40 nm, and a lattice fringe spacing of 0.96 nm, corresponding to the (100) plane of the todorokite structure. The [010] HRTEM fringe images show that the tunnels contained a constant triple-chain width (3 × 3) along the c and a axes. The Co(N)-todorokite consists of a chemical composition of Co_0.11N_0.48H_1.39MnO_1.99·H₂O_x. Thermogravity analysis (TGA) indicates that these nanofibers are thermally stable up to 400 °C. The Brunauer−Emmett−Teller (BET) surface area for Co(N)-todorokite is 98.2 m²/g, which is higher than that of bulk todorokite materials. The Horvath−Kawazoe (HK) plot shows a major pore size distribution peak centered at 0.71 nm for Co(N)-todorokite.