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首页> 外文期刊>RSC Advances >A possible mechanism for the emergence of an additional band gap due to a Ti-O-C bond in the TiO2-graphene hybrid system for enhanced photodegradation of methylene blue under visible light
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A possible mechanism for the emergence of an additional band gap due to a Ti-O-C bond in the TiO2-graphene hybrid system for enhanced photodegradation of methylene blue under visible light

机译：TiO2-石墨烯杂化系统中由于Ti-O-C键而产生额外的带隙的可能机制，用于在可见光下增强亚甲基蓝的光降解

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Here we report the experimental and theoretical study of two TiO2-graphene oxide (TG) and TiO2-reduced graphene oxide (TR) composites synthesized by a facile and ecological route, for enhanced visible light (similar to 470 nm) photocatalytic degradation of Methylene Blue (MB) (99% efficiency), with high rate constant values (1800% over bare TiO2). TG couples TiO2 nanopowder with Graphene Oxide (GO) while TR couples it with reduced graphene oxide (RGO). The present study, unlike previous reports, discusses never-before-reported double absorption edges obtained for both TG (3.51 eV and 2.51 eV) and TR (3.42 eV and 2.39 eV) composites, which represents the reason behind feasible visible light (2.56 eV) induced photocatalysis. TiO2 domains in the composites dominate the higher band edge, while GO/RGO domains explain the lower band edge. Formation of Ti-O-C bonds in both TG and TR drives the shifting upwards of the valence band edge and reduction in band gap. Further, these bonds provide a conductive pathway for charge carriers from TiO2 nanopowder to the degraded species via the GO/RGO matrix, resulting in decreased charge carrier recombination in TiO2 and enhanced efficiency. To attest that the developed theory is correct, density function theory (DFT) calculations were performed. DFT obtained energetics and electronic structures support experimental findings by demonstrating the role of the Ti-O-C bond, which results in double band edge phenomenon in composites. Finally, the mechanism behind MB degradation is discussed comprehensively and the effect of the weight percent of GO/RGO in the composite on the rate constant and photodegradation efficiency has been studied experimentally and explained by developing analytical equations.
机译：在这里，我们报告了通过一种简便且生态的途径合成的两种TiO2-氧化石墨烯（TG）和TiO2还原氧化石墨烯（TR）复合材料的实验和理论研究，以增强可见光（类似于470 nm）对亚甲基蓝的光催化降解（MB）（效率为99％），具有较高的速率常数值（裸露的TiO2为1800％）。 TG将TiO2纳米粉与氧化石墨烯（GO）偶联，而TR与还原的氧化石墨烯（RGO）偶联。与先前的报告不同，本研究讨论了TG（3.51 eV和2.51 eV）和TR（3.42 eV和2.39 eV）复合材料获得的前所未有的双吸收边，这代表了可见光（2.56 eV）背后的原因。 ）诱导光催化。复合材料中的TiO2域占据了较高的带边缘，而GO / RGO域则解释了较低的带边缘。 TG和TR中Ti-O-C键的形成驱动价带边缘的向上移动和带隙的减小。此外，这些键为从TiO2纳米粉到GO / RGO基质的降解物种提供了电荷传导的导电途径，从而导致TiO2中的电荷载流子重组减少并提高了效率。为了证明所开发的理论是正确的，进行了密度函数理论（DFT）计算。 DFT获得的高能学和电子结构通过证明Ti-O-C键的作用来支持实验结果，这会导致复合材料出现双带边缘现象。最后，对MB降解的机理进行了全面的讨论，并通过实验研究了解析方程，对GO / RGO在复合材料中的重量百分率对速率常数和光降解效率的影响进行了实验研究。

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