General Strategy to Synthesize Uniform Mesoporous TiO2/Graphene/Mesoporous TiO2 Sandwich-Like Nanosheets for Highly Reversible Lithium Storage
General Strategy to Synthesize Uniform Mesoporous TiO2/Graphene/Mesoporous TiO2 Sandwich-Like Nanosheets for Highly Reversible Lithium Storage
复制标题
合成均匀介孔 TiO2/石墨烯/介孔 TiO2 三明治状纳米片用于高度可逆锂存储的一般策略
DOI：
10.1021/acs.nanolett.5b00291
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发表时间：
2015-03-01
期刊：
影响因子：
10.8
通讯作者：
Zhao, Dongyuan
中科院分区：
文献类型：
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作者：
Li, Wei;Wang, Fei;Zhao, Dongyuan
在石墨烯上均匀沉积氧化物以形成类石墨烯构造是众所周知的挑战，主要是由于它们的大的晶格失配和差的亲和力。在此，我们报道了一种合成均匀的介孔TiO 2/石墨烯/介孔TiO 2纳米片（记为G@mTiO（2））的一般策略，这是传统的一锅合成方法无法实现的。我们发现，通过合理控制Ti前驱体的水解和缩合，GO片可以被无定形TiO 2壳层均匀包覆，然后通过退火可以很容易地转化为定义明确的G@mTiO（2）纳米片。这种无定形到结晶的策略方便地允许绕过应变场，如果在石墨烯上直接生长介孔介孔壳，则不可避免地会出现应变场。与石墨烯基复合材料（混合、包裹或锚定模型）的最常见结构不同，所得材料显示出均匀的类石墨烯结构：少层石墨烯被介孔TiO 2壳一致地封装。这种新的G@mTiO（2）纳米片具有纳米性质（类似于34 nm）、小尺寸和高结晶纳米晶体（类似于6 nm）、高比表面积（类似于252 m2/g）和均匀的介孔（类似于3.4 nm）。我们进一步表明，通过控制氨含量，可以根据需要轻松调节介孔TiO 2壳的厚度，并且这种简单的策略可以很容易地扩展到设计其他氧化物/石墨烯/氧化物三明治状材料。更重要的是，我们展示了所得G@mTiO（2）纳米片作为锂离子电池阳极的好处：它们提供了超高的容量，出色的高倍率性能和长循环寿命。
Uniform oxide deposition on graphene to form a sandwich-like configuration is a well-known challenge mainly due to their large lattice mismatches and poor affinities. Herein, we report a general strategy to synthesize uniform mesoporous TiO2/graphene/mesoporous TiO2 sandwich-like nanosheets (denoted as G@mTiO(2)), which cannot be achieved by conventional one-pot synthetic methods. We show that by rational control of hydrolysis and condensation of Ti precursors in a slow way, GO sheets can be conformably coated by amorphous TiO2 shells, which then can be facilely transformed into the well-defined G@mTiO(2) nanosheets by annealing. This amorphous-to-crystalline strategy conveniently allows bypassing strain fields that would inevitably arise if direct growth of mesoporous anatase shells on graphene. As distinct from the most common structures of graphene-based composites (mixed, wrapped, or anchored models), the resultant materials display a uniform sandwich-like configuration: few-layer graphene conformably encapsulated by mesoporous TiO2 shells. This new G@mTiO(2) nanosheet exhibits ultrathin nature (similar to 34 nm), small size and high crystalline nanocrystals (similar to 6 nm), high surface areas (similar to 252 m(2)/g) and uniform mesopores (similar to 3.4 nm). We further show that the thickness of mesoporous TiO2 shells can be facilely adjusted as desired by controlling the ammonia content, and this facile strategy can be easily extended to design other oxide/graphene/oxide sandwich-like materials. More importantly, we showcase the benefits of the resultant G@mTiO(2) nanosheets as anodes in lithium ion batteries: they deliver an extra high capacity, an excellent high-rate capability, and long cycle life.