Gr/NiFe2O4纳米复合材料的制备与形成机理研究

以氧化石墨烯(GO)、Fe2(SO4)3和NiSO4为初始反应物,利用一步水热法合成了Gr/NiFe2O4纳米复合材料。采用X射线衍射(XRD)、透射电子显微镜(TEM)和拉曼光谱(RS)等分析手段对Gr/NiFe2O4样品进行了表征。结果表明:经过水热反应GO被还原的同时,纳米NiFe2O4成功地负载到石墨烯上,二者之间存在较强的界面相互作用,而且NiFe2O4纳米粒子增加了石墨烯片层间的距离避免了其再次堆垛,实现了石墨烯与NiFe2O4的良好复合。初步讨论了Gr/NiFe2O4纳米复合材料的形成机制,Ni2+、Fe3+在GO的含氧基团处非均相成核,在水热条件下不断长大,其生长过程遵循Ostwald熟化理论,即小尺寸的NiFe2O4粒子由于其较高的表面能而逐渐溶解,被那些尺寸较大的粒子消耗。

One-pot Hydrothermal Synthesis and Formation Mechanism of Gr/NiFe2O4 Nanocomposites

Graphene/NiFe2O4 (Gr/NiFe2O4) nanocomposites were synthesized using a facile one-pot hydrothermal method with graphene oxide (GO), Fe2(SO4)3 and NiSO4 as starting materials. The as-prepared Gr/NiFe2O4 was characterized using X-ray diffraction (XRD), transmission electron microscope (TEM), and Raman spectra (RS). The results indicate that GO is reduced to graphene and the well-dispersed NiFe2O4 nanoparticles are simultaneously deposited onto graphene sheets under the conditions generated by the hydrothermal system. There is a strong interface interaction between the graphene and NiFe2O4 nanoparticles, which avoids their aggregation. The formation mechanism of Gr/NiFe2O4 nanocomposites was discussed. The growth kinetics of NiFe2O4 nanoparticles follows the Ostwald ripening, in which smaller particles dissolve owing to their high surface energy and are essentially consumed by larger ones.