Centre for Clean Environment and Energy, Griffith School of Environment, Griffith University, Gold Coast Campus, Queensland 4222, Australia.
Small. 2013 Oct 11;9(19):3336-44. doi: 10.1002/smll.201203135. Epub 2013 Apr 30.
Cross-linked rather than non-covalently bonded graphitic carbon nitride (g-C3 N4 )/reduced graphene oxide (rGO) nanocomposites with tunable band structures have been successfully fabricated by thermal treatment of a mixture of cyanamide and graphene oxide with different weight ratios. The experimental results indicate that compared to pure g-C3 N4 , the fabricated CN/rGO nanocomposites show narrowed bandgaps with an increased in the rGO ratio. Furthermore, the band structure of the CN/rGO nanocomposites can be readily tuned by simply controlling the weight ratio of the rGO. It is found that an appropriate rGO ratio in nanocomposite leads to a noticeable positively shifted valence band edge potential, meaning an increased oxidation power. The tunable band structure of the CN/rGO nanocomposites can be ascribed to the formation of C-O-C covalent bonding between the rGO and g-C3 N4 layers, which is experimentally confirmed by Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) data. The resulting nanocomposites are evaluated as photocatalysts by photocatalytic degradation of rhodamine B (RhB) and 4-nitrophenol under visible light irradiation (λ > 400 nm). The results demonstrate that the photocatalytic activities of the CN/rGO nanocomposites are strongly influenced by rGO ratio. With a rGO ratio of 2.5%, the CN/rGO-2.5% nanocomposite exhibits the highest photocatalytic efficiency, which is almost 3.0 and 2.7 times that of pure g-C3 N4 toward photocatalytic degradation of RhB and 4-nitrophenol, respectively. This improved photocatalytic activity could be attributed to the improved visible light utilization, oxidation power, and electron transport property, due to the significantly narrowed bandgap, positively shifted valence band-edge potential, and enhanced electronic conductivity.
通过热处理不同质量比的氰胺和氧化石墨烯混合物，成功制备了具有可调带隙的交联而非非共价键合的石墨相氮化碳（g-C3N4）/还原氧化石墨烯（rGO）纳米复合材料。实验结果表明，与纯 g-C3N4 相比，制备的 CN/rGO 纳米复合材料具有较窄的带隙，随着 rGO 比例的增加而增加。此外，通过简单控制 rGO 的重量比，很容易调节 CN/rGO 纳米复合材料的能带结构。研究发现，纳米复合材料中 rGO 的适当比例会导致价带边缘势的明显正移，这意味着氧化能力增强。CN/rGO 纳米复合材料的可调带隙结构归因于 rGO 和 g-C3N4 层之间形成的 C-O-C 共价键，这通过傅里叶变换红外（FT-IR）和 X 射线光电子能谱（XPS）数据得到了实验证实。将所得纳米复合材料作为光催化剂，通过在可见光照射（λ>400nm）下光催化降解罗丹明 B（RhB）和 4-硝基苯酚来评估其性能。结果表明，CN/rGO 纳米复合材料的光催化活性强烈受 rGO 比例的影响。在 rGO 比例为 2.5%时，CN/rGO-2.5%纳米复合材料表现出最高的光催化效率，对于 RhB 和 4-硝基苯酚的光催化降解，其效率分别是纯 g-C3N4 的近 3.0 和 2.7 倍。这种提高的光催化活性可以归因于显著缩小的带隙、价带边缘势的正移以及增强的电子传导性，从而提高了可见光利用率、氧化能力和电子传输性能。
