Nanoparticle-functionalized 2D material networks are promising for a wide range of applications, but in situ formation of nanoparticles is commonly challenged by rapid growth. Here, we demonstrate controlled synthesis of small and dispersed iron oxide nanoparticles on reduced graphene oxide (rGO) networks through rapid localized heating with microwaves with low-cost iron nitrate as the precursor. The strong coupling of the microwave radiation with the rGO network rapidly heats the network locally to decompose the iron nitrate and generate iron oxide nanoparticles, while cessation of microwaves leads to rapid cooling to minimize crystal growth. Small changes in the microwave reaction time (<1 min) led to very large changes in the iron oxide morphology. The solid-state microwave syntheses produced narrower nanoparticle size distribution than conventional heating. These results illustrate the potential of solid-state microwave syntheses to control the nanoparticle size on 2D materials through rapid localized heating under the microwave process conditions, which should be extendable to a variety of transition metal oxide–rGO systems.

中文翻译：

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还原氧化石墨烯上氧化铁纳米粒子的微波尺寸控制

纳米粒子功能化的二维材料网络有广泛的应用前景，但纳米粒子的原位形成通常受到快速生长的挑战。在这里，我们展示了通过以低成本硝酸铁作为前体的微波快速局部加热，在还原氧化石墨烯 (rGO) 网络上可控合成小而分散的氧化铁纳米颗粒。微波辐射与 rGO 网络的强耦合会迅速加热网络局部以分解硝酸铁并生成氧化铁纳米颗粒，同时停止微波会导致快速冷却以最大程度地减少晶体生长。微波反应时间（<1 分钟）的微小变化会导致氧化铁形态发生非常大的变化。固态微波合成产生比传统加热更窄的纳米颗粒尺寸分布。这些结果说明了固态微波合成在微波工艺条件下通过快速局部加热控制二维材料纳米颗粒尺寸的潜力，这应该可以扩展到各种过渡金属氧化物-rGO 系统。