Direct Observation of Single Layer Graphene Oxide Reduction through Spatially Resolved, Single Sheet Absorption/Emission Microscopy
Direct Observation of Single Layer Graphene Oxide Reduction through Spatially Resolved, Single Sheet Absorption/Emission Microscopy
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DOI：
10.1021/nl500485n
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发表时间：
2014-06-01
期刊：
影响因子：
10.8
通讯作者：
Kuno, Masaru
中科院分区：
文献类型：
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作者：
Sokolov, Denis A.;Morozov, Yurii V.;Kuno, Masaru
氧化石墨烯（GO）的激光还原为石墨烯的快速非化学生产提供了独特的机会。通过调节还原参数，可以精确控制还原GO的带隙和电导率。因此，原位监测单层GO还原是必要的。在这份报告中，我们通过其吸收和发射的相关变化显示了激光诱导的单层GO还原的直接观察。吸收/发射电影说明了单层GO还原的初始阶段、其向还原GO（rGO）的转变以及其在长时间激光照射后的后续分解。这些研究揭示了GO的光还原生命周期，并通过它的天然GO/rGO吸收系数，它们的内部分布以及它们的空间异质性。未还原GO的提取吸收系数为α（405）（nm）约为6.5 +/- 1.1 × 10（4）cm（-1），α（520）（nm）约为2.1 +/- 0.4 × 10（4）cm（-1），和α（640）（nm）近似为1.1 +/-0.3 × 10（4）cm（-1），而相应的rGO α值为α（405）（nm）近似为21.6 +/-0.6 × 10（4）cm（-1），α（520）（nm）近似于16.9 +/- 0.4 x对GO的潜在光还原机制的前所未有的洞察，考虑到我们空间分辨其动力学的能力和10（4）cm（-1），α（640）（nm）近似于14.5 +/- 0.4 x 10（4）cm（-1）。更重要的是，相关的吸收/发射成像为我们提供了连接本地速率常数的活化能。在更广泛的层面上，所开发的吸收成像是通用的，并且可以应用于研究其他二维材料的光学性质，特别是那些非发射性的并且对当前单分子光学技术不可见的材料。
Laser reduction of graphene oxide (GO) offers unique opportunities for the rapid, nonchemical production of graphene. By tuning relevant reduction parameters, the band gap and conductivity of reduced GO can be precisely controlled. In situ monitoring of single layer GO reduction is therefore essential. In this report, we show the direct observation of laser-induced, single layer GO reduction through correlated changes to its absorption and emission. Absorption/emission movies illustrate the initial stages of single layer GO reduction, its transition to reduced-GO (rGO) as well as its subsequent decomposition upon prolonged laser illumination. These studies reveal GO's photoreduction life cycle and through it native GO/rGO absorption coefficients, their intrasheet distributions as well as their spatial heterogeneities. Extracted absorption coefficients for unreduced GO are alpha(405) (nm) approximate to 6.5 +/- 1.1 x 10(4) cm(-1), alpha(520) (nm) approximate to 2.1 +/- 0.4 x 10(4) cm(-1), and alpha(640) (nm) approximate to 1.1 +/- 0.3 x 10(4) cm(-1) while corresponding rGO alpha-values are alpha(405) (nm) approximate to 21.6 +/- 0.6 x 10(4) cm(-1), alpha(520) (nm) approximate to 16.9 +/- 0.4 x unprecedented insight into GO's underlying photoreduction mechanism, given our ability to spatially resolve its kinetics and to 10(4) cm(-1), and alpha(640) (nm) approximate to 14.5 +/- 0.4 x 10(4) cm(-1). More importantly, the correlated absorption/emission imaging provides us with connect local rate constants to activation energies. On a broader level, the developed absorption imaging is general and can be applied toward investigating the optical properties of other two-dimensional materials, especially those that are nonemissive and are invisible to current single molecule optical techniques.