Sun Chunwen, Su Rui, Chen Jian, Lu Liang, Guan Pengfei
CAS Center for Excellence in Nanoscience, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, P. R. China.
School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
ACS Omega. 2019 May 13;4(5):8413-8420. doi: 10.1021/acsomega.9b00958. eCollection 2019 May 31.
Understanding the carbon formation mechanism is critical for designing catalysts in various applications. Here, we report the observation of the carbon formation mechanism on Ni-based catalysts by environmental transmission electron microscopy (ETEM) over a wide temperature range in combination with molecular dynamics simulations and density functional theory calculations. In situ TEM observation performed in a CH/H atmosphere provides real-time evidence that NiC is an intermediate phase that decomposes to graphitic carbon and metallic Ni, leading to carbon formation. Mechanisms of acetylene decomposition and evolution of carbon atom configuration are revealed by molecular dynamics simulations, which corroborate the experimental results. The modification of MgO on NiO can effectively decrease the formation of graphitic layers and thus enhance the catalytic performance of NiO. This finding may provide an insight into the origin of the carbon deposition and aid in developing effective approaches to mitigate it.
了解碳形成机制对于设计各种应用中的催化剂至关重要。在此，我们报告了通过环境透射电子显微镜（ETEM）在较宽温度范围内结合分子动力学模拟和密度泛函理论计算对镍基催化剂上碳形成机制的观察。在CH/H气氛中进行的原位TEM观察提供了实时证据，表明NiC是分解为石墨碳和金属Ni从而导致碳形成的中间相。分子动力学模拟揭示了乙炔分解机制和碳原子构型的演变，这证实了实验结果。MgO对NiO的改性可以有效减少石墨层的形成，从而提高NiO的催化性能。这一发现可能有助于深入了解碳沉积的起源，并有助于开发减轻碳沉积的有效方法。
