University of KwaZulu-Natal, Westville Campus, School of Chemistry and Physics, Private Bag X54001, Durban 4000, South Africa.
Nanotechnology. 2017 Dec 8;28(49):495703. doi: 10.1088/1361-6528/aa9299.
Graphene provides numerous possibilities for structural modification and functionalization of its carbon backbone. Localized magnetic moments can, as well, be induced in graphene by the formation of structural defects which include vacancies, edges, and adatoms. In this work, graphene was functionalized using germanium atoms, we report the effect of the Ge ad atoms on the structural, electrical, optical and magnetic properties of graphene. Reduced graphene oxide (rGO)-germanium quantum dot nanocomposites of high crystalline quality were synthesized by the microwave-assisted solvothermal reaction. Highly crystalline spherical shaped germanium quantum dots, of diameter ranging between 1.6-9.0 nm, are anchored on the basal planes of rGO. The nanocomposites exhibit high electrical conductivity with a sheet resistance of up to 16 Ω sq. The electrical conductivity is observed to increase with the increase in Ge content in the nanocomposites. High defect-induced magnetization is attained in the composites via germanium adatoms. The evolution of the magnetic moments in the nanocomposites and the coercivity showed marked dependence on the Ge quantum dots size and concentration. Quantum confinement effects is evidenced in the UV-vis absorbance spectra and photoluminescence emission spectra of the nanocomposites which show marked size-dependence. The composites manifest strong absorption in the UV region, strong luminescence in the near UV region, and a moderate luminescence in the visible region.
石墨烯为其碳主链的结构修饰和功能化提供了众多可能性。通过形成包括空位、边缘和 adatoms 在内的结构缺陷，也可以在石墨烯中诱导局部磁矩。在这项工作中，我们使用锗原子对石墨烯进行了功能化，报告了 Ge ad 原子对石墨烯的结构、电学、光学和磁性能的影响。通过微波辅助溶剂热反应合成了具有高结晶质量的还原氧化石墨烯（rGO）-锗量子点纳米复合材料。高度结晶的球形锗量子点，直径在 1.6-9.0nm 之间，锚定在 rGO 的基面。纳米复合材料表现出高达 16 Ω sq 的高电导率。观察到电导率随纳米复合材料中 Ge 含量的增加而增加。通过锗 adatoms 在复合材料中获得了高的缺陷诱导磁化。复合材料中的磁矩的演化和矫顽力表现出明显依赖于 Ge 量子点的尺寸和浓度。在纳米复合材料的 UV-vis 吸收光谱和光致发光发射光谱中证实了量子限制效应，它们表现出明显的尺寸依赖性。复合材料在 UV 区域表现出强烈的吸收，在近 UV 区域表现出强烈的发光，在可见区域表现出适中的发光。
