Center for Intelligent Nano-Bio Materials, Department of Chemistry and Nano Sciences, Ewha Womans University, Seoul, Korea.
Chemistry. 2012 Oct 22;18(43):13800-9. doi: 10.1002/chem.201200551. Epub 2012 Sep 17.
Graphene nanosheets are successfully applied as an effective platform for the 2D ordering of metal oxide nanoparticles. Mesoporous 2D aggregates of anatase TiO(2) nanoparticles are synthesized by the heat treatment of the uniformly hybridized nanocomposite of layered titanate-reduced graphene oxide (RGO) at elevated temperatures. The precursor layered titanate-RGO nanocomposite is prepared by self-assembly of anionic RGO nanosheets and cationic TiO(2) nanosols. The calcination of the as-prepared layered titanate-RGO nanocomposite at 500 °C induces a structural and morphological change of layered titanate nanoplates into anatase TiO(2) nanoparticles without significant modification of the RGO nanosheet. Increasing the heating temperature to 600 °C gives rise to elimination of the RGO component, leading to the formation of sheetlike porous aggregates of RGO-free TiO(2) nanoparticles. The nanocomposites calcined at 500-700 °C display promising functionality as negative electrodes for lithium ion batteries. Among the present calcined derivatives, the 2D sheet-shaped aggregate of TiO(2) nanoparticles obtained from calcination at 600 °C delivers the greatest specific discharge capacity with good capacity retention for all current density conditions applied. Such superior electrode performance of the nanocomposite calcined at 600 °C is attributable both to the improved stability of the crystal structure and crystal morphology of titania and to the enhancement of Li(+) ion transport through the enlargement of mesopores. The present findings clearly demonstrate the usefulness of RGO nanosheets as a platform for 2D-ordered superstructures of metal oxide nanoparticles with improved electrode performance.
石墨烯纳米片成功地应用于金属氧化物纳米粒子的二维有序化平台。通过在高温下热处理均匀杂化的层状钛酸盐-还原氧化石墨烯（RGO）纳米复合材料，合成了具有介孔二维结构的锐钛矿 TiO(2) 纳米粒子的 2D 聚集体。前驱体层状钛酸盐-RGO 纳米复合材料是通过阴离子 RGO 纳米片和阳离子 TiO(2) 纳米溶胶的自组装制备的。在 500°C 下煅烧所得的层状钛酸盐-RGO 纳米复合材料会导致层状钛酸盐纳米片的结构和形态发生变化，形成锐钛矿 TiO(2) 纳米粒子，而 RGO 纳米片没有明显的变化。将加热温度提高到 600°C 会导致 RGO 成分的消除，从而形成无 RGO 的 TiO(2) 纳米粒子的片状多孔聚集体。在 500-700°C 下煅烧的纳米复合材料作为锂离子电池的负极表现出良好的性能。在所研究的煅烧衍生物中，在 600°C 下煅烧得到的 2D 片状 TiO(2) 纳米粒子聚集体在所有应用电流密度条件下都具有最大的比放电容量和良好的容量保持率。纳米复合材料在 600°C 下煅烧的这种优异的电极性能归因于钛酸晶体结构和晶体形态的稳定性提高以及通过介孔增大改善了 Li(+) 离子的传输。本研究结果清楚地表明了 RGO 纳米片作为具有改进的电极性能的金属氧化物纳米粒子的二维有序超结构的平台的有用性。
