Liaros Nikos, Tucek Jiri, Dimos Konstantinos, Bakandritsos Aristides, Andrikopoulos Konstantinos S, Gournis Dimitrios, Zboril Radek, Couris Stelios
Department of Physics, University of Patras, 26504 Patras, Greece.
Regional Centre of Advanced Technologies & Materials, Departments of Physical Chemistry and Experimental Physics, Faculty of Science, Palacky University, 17, listopadu 1192/12, 771 46 Olomouc, Czech Republic.
Nanoscale. 2016 Feb 7;8(5):2908-17. doi: 10.1039/c5nr07832f.
We report on the effect of the degree of oxidation on the broadband non-linear optical response and magnetic behavior of graphene oxide, as well as on a route for obtaining reduced graphene oxide with enhanced optical properties without sacrificing the high dispersibility of the parent graphene oxide. As more sp(3) states evolved with the rise in oxidation degree, it turned out that the sp(2)/sp(3) fraction and sp(2) clustering are crucial parameters for tuning the broadband non-linear optical absorption over a wide range from ps to ns laser pulses for both visible and infrared laser irradiation. This was clearly confirmed by two different approaches, namely by a synthetic route through the gradual oxidation of graphene oxide from 1 to 3 oxidizing cycles, and reversely by in situ reduction of graphene oxide by UV laser irradiation. Furthermore, as the sp(3) states carry localized magnetic moments, ferromagnetic ordering is observed at low temperatures. The magnetization and temperature at which ferromagnetic ordering evolves are found to increase on increasing the oxidation degree. The tuning of non-linear optical and magnetic properties of graphene oxide by oxidation/reduction thus provides an easy way to endow graphene oxide with tunable physical features highly required in both optoelectronics and spintronics applications.
我们报道了氧化程度对氧化石墨烯的宽带非线性光学响应和磁行为的影响，以及一种在不牺牲母体氧化石墨烯高分散性的情况下获得具有增强光学性能的还原氧化石墨烯的途径。随着氧化程度的增加，更多的sp(3)态得以演化，结果表明，对于可见光和红外激光照射，从皮秒到纳秒激光脉冲的宽范围内，sp(2)/sp(3)比例和sp(2)团簇是调节宽带非线性光学吸收的关键参数。这通过两种不同的方法得到了明确证实，一种是通过将氧化石墨烯从1个氧化循环逐步氧化到3个氧化循环的合成路线，另一种是通过紫外激光照射对氧化石墨烯进行原位还原。此外，由于sp(3)态携带局域磁矩，在低温下观察到铁磁有序。发现随着氧化程度的增加，铁磁有序演化时的磁化强度和温度会升高。因此，通过氧化/还原对氧化石墨烯的非线性光学和磁性能进行调控，为赋予氧化石墨烯在光电子学和自旋电子学应用中高度所需的可调物理特性提供了一种简便方法。
