Graphene-wrapped hierarchical TiO2 nanoflower composites with enhanced photocatalytic performance
Graphene-wrapped hierarchical TiO2 nanoflower composites with enhanced photocatalytic performance
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DOI：
10.1039/c3ta12329d
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发表时间：
2013-01-01
影响因子：
11.9
通讯作者：
Yu, Aiping
中科院分区：
文献类型：
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作者：
Lui, Gregory;Liao, Jin-Yun;Yu, Aiping
采用溶剂/水热两步法合成了由纳米片和纳米颗粒组成的石墨烯包裹二氧化钛纳米花复合材料（G-TiO2）。采用扫描电镜（SEM）、透射电镜（TEM）、高分辨率透射电镜（HRTEM）、XRD、拉曼光谱（Raman spectroscopy）和红外光谱（FTIR）对材料进行了表征。进一步分析采用布兰诺尔-埃米特-泰勒（BET）比表面积分析、电化学阻抗谱（EIS）、紫外-可见光谱和漫反射紫外-可见光谱。采用紫外光降解法测定了亚甲基蓝的光催化活性。结果表明，TiO2纳米花的光催化活性比商用P25高1.49倍。这是由于纳米花结构的高度结晶性和层级性，它提供了改进的电荷输运和光产生的电子-空穴对的重组率降低。经石墨烯包裹后，G-TiO2复合材料可以通过提供一个平面共轭表面来吸附染料，通过接受TiO2的电子进一步减少复合，并在光吸收中引起红移，从而进一步提高光催化性能。使用5 wt%的石墨烯负载时，发现最高的光催化性能，比商用P25高出3.4倍。
Graphene-wrapped titanium dioxide nanoflower composites (G-TiO2) consisting of nanosheets and nanoparticles were synthesized using a two-step solvo/hydrothermal process. Materials were characterized using SEM, TEM, high-resolution TEM (HRTEM), XRD, Raman spectroscopy, and FTIR. Further analysis was performed using Branauer-Emmett-Teller (BET) specific surface area analysis, electrochemical impedance spectroscopy (EIS), UV-Vis spectroscopy, and diffuse reflectance UV-Vis spectroscopy. Photocatalytic activity was determined by the photo-degradation of methylene blue under UV irradiation. Results show that the TiO2 nanoflower exhibits a higher photocatalytic activity than commercial P25 by a factor of 1.49. This is attributed to the highly crystalline, hierarchical nature of the nanoflower structure, which provides improved charge transport and a reduced recombination rate of photo-generated electron-hole pairs. After wrapping with graphene, the G-TiO2 composite can further improve the photocatalytic performance by providing a planar conjugated surface for dye adsorption, by further reducing recombination through accepting electrons from TiO2, and by causing a red shift in light absorption. The highest photocatalytic performance was found using a graphene loading of 5 wt%, which outperforms commercial P25 by a factor of 3.4.