Nanchang Hangkong University, Department of Material Chemistry, Nanchang, Jiangxi Province, China.
Nanchang Hangkong University, Department of Material Chemistry, Nanchang, Jiangxi Province, China.
J Hazard Mater. 2016 Nov 15;318:551-560. doi: 10.1016/j.jhazmat.2016.07.046. Epub 2016 Jul 19.
In this work we have developed a unique structure of ultrathin (5nm) TiO2 nanolayers grafted graphene nanosheets (TiO2/G) and integrated oxygen vacancy (VO) into TiO2 to enhance its lithium storage and photocatalytic performances. The defective TiO2/G was synthesized by a solvothermal and subsequent thermal treatment method. When treated in a H2 atmosphere, the resulting TiO2-x/G(H2) has lower crystallinity, smaller crystal size, richer surface VO, higher surface area, larger pore volume, and lower charge transfer resistance than that reduced by NaBH4 solid, i.e., TiO2-x/G(NaBH4). More importantly, the surface VO in the TiO2-x/G(H2) could remarkably inhibit the recombination of photogenerated electron-hole pairs compared with the bulk Vo in the TiO2-x/G(NaBH4). As a result, the combination of all the factors contributed to the superiority of TiO2-x/G(H2), which demonstrated not only 70% higher specific capacity, longer cycling performance (1000 cycles) and better rate capability for lithium-ion battery, but also higher photocatalytic activity and 1.5 times faster degradation rate for organic pollutants removal than TiO2-x/G(NaBH4). The findings in this work will benefit the fundamental understanding of TiO2/G surface chemistry and advance the design and preparation of functional materials for energy storage and water treatment.
在这项工作中，我们开发了一种独特的结构，即超薄（5nm）的 TiO2 纳米层接枝石墨烯纳米片（TiO2/G），并将氧空位（VO）整合到 TiO2 中，以提高其储锂和光催化性能。缺陷型 TiO2/G 通过溶剂热和随后的热处理方法合成。当在 H2 气氛中处理时，所得的 TiO2-x/G(H2) 的结晶度较低、晶体尺寸较小、表面 VO 更丰富、比表面积更大、孔体积更大、电荷转移电阻更小，而通过 NaBH4 固体还原的 TiO2-x/G(NaBH4)则具有更高的结晶度、更大的晶体尺寸、更丰富的表面 VO、更大的比表面积、更大的孔体积和更小的电荷转移电阻。更重要的是，TiO2-x/G(H2)中的表面 VO 可以显著抑制光生电子-空穴对的复合，而 TiO2-x/G(NaBH4)中的体相 VO 则不能。因此，所有因素的结合使得 TiO2-x/G(H2)具有优越性，它不仅表现出 70%更高的比容量、更长的循环性能（1000 次循环）和更好的倍率性能，而且在光催化活性和有机污染物去除速率方面也表现出 1.5 倍的提高。本工作的发现将有助于深入了解 TiO2/G 表面化学，并推动储能和水处理功能性材料的设计和制备。
