Abstract In situ X-ray diffraction measurement was performed to study the precipitation mechanism of graphene from Ni catalyst with and without Ti capping layer using X-ray beam from a synchrotron radiation facility. The graphene precipitated on the surface of the catalyst in the case without the Ti capping layer while it did at the interface between the catalyst and the sapphire substrate in the case with the Ti capping layer. Each process, such as graphene nucleation and precipitation was successfully monitored even though graphene precipitated under the metal catalyst. The detailed mechanisms for both cases were discussed using the experimental results. Consequently, the crystallization of the catalyst is found to effectively suppress the precipitation at low temperature, which is useful to improve the quality of the precipitated graphene. The adjustment of the amount of the carbons is another important factor to precisely control the precipitation because graphene also precipitates after the carbons saturate the catalyst.

中文翻译：

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X 射线原位观察石墨烯直接沉淀在有和没有 Ti 覆盖层的蓝宝石衬底上

摘要 使用同步辐射设备的X射线束原位X射线衍射测量研究石墨烯从有和没有Ti覆盖层的Ni催化剂中析出的机理。在没有Ti覆盖层的情况下，石墨烯沉淀在催化剂表面，而在有Ti覆盖层的情况下，它在催化剂和蓝宝石衬底之间的界面上沉淀。即使石墨烯在金属催化剂下沉淀，每个过程，如石墨烯成核和沉淀，也能成功监测。使用实验结果讨论了这两种情况的详细机制。因此，发现催化剂的结晶有效地抑制了低温下的沉淀，这有助于提高沉淀石墨烯的质量。