General Recyclable Redox-Metallothermic Reaction Route to Hierarchically Porous Carbon/Metal Composites

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• 作者：Kyung Joo Lee ; Sinho Choi ; Soojin Park ; Hoi Ri Moon
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：June 28, 2016
• 年：2016
• 卷：28
• 期：12
• 页码：4403-4408
• 全文大小：380K
• 年卷期：0
• ISSN：1520-5002

文摘

Herein, we develop a general synthetic route to obtain composites of porous carbon and electrochemically active metal particles such as Ge, In, Bi, and Sn. The thermolysis of a Zn-based metal–organic framework (MOF) produces hierarchically porous carbon (HPC) and metallic Zn at high temperatures, which can act as a reducing agent of metal oxides. In the reaction system of a Zn-based MOF with GeO₂, in situ evolved Zn reduces GeO₂, producing Ge and ZnO. Interestingly, ZnO is automatically reduced to Zn via a carbothermic reduction during the conversion process, which returns reducing agent to the reaction. Thus, the repeated occurrence of the zincothermic and carbothermic reduction reactions promotes a recyclable redox-metallothermic reaction. After complete reduction of GeO₂, Zn metal is spontaneously vaporized to yield Ge/HPC composites. This facile method can be successfully extended to other metal oxides including In₂O₃, Bi₂O₃, and SnO. The as-synthesized Ge/HPC is tested as a rechargeable battery anode material, which exhibits a reversible capacity as high as ∼600 mA h g^–1 after 300 cycles at a rate of 0.5 C and a low electrode volume expansion (less than 30%).