Liu Boyang, van Schooneveld Matti M, Cui Yi-Tao, Miyawaki Jun, Harada Yoshihisa, Eschemann Thomas O, de Jong Krijn P, Delgado-Jaime Mario U, de Groot Frank M F
Inorganic Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, Utrecht, 3584 CG, The Netherlands.
Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
J Phys Chem C Nanomater Interfaces. 2017 Aug 17;121(32):17450-17456. doi: 10.1021/acs.jpcc.7b04325. Epub 2017 Jul 14.
In-situ carbon-thermal reduction of cobalt oxide nanoparticles supported on carbon nanotubes was studied by cobalt 2p3d resonant inelastic X-ray scattering (RIXS). The in-situ 2p X-ray absorption spectroscopy (XAS) and RIXS measurements were performed at 500, 600, and 700 °C, where four consistent excitation energies were used for RIXS acquisitions. After 700 °C reduction, the XAS spectrum shows a cobalt metal-like shape, while the RIXS spectra reveal the minority cobalt monoxide phase. The holistic fit on both XAS and RIXS data reveals the respective contributions from metal and monoxide. We show that the relative precision to determine the monoxide content changes from ∼5.6% in XAS results to better than 0.8% in the RIXS analysis, suggesting that RIXS is a useful tool to track the oxidation state of nanoparticles under in situ conditions. We determined a relative radiative ratio () factor of approximately 5, where this factor gives the ratio between the relative strengths of the radiative decay channels compared to the nonradiative channels in CoO and Co metal.
通过钴2p3d共振非弹性X射线散射（RIXS）研究了负载在碳纳米管上的氧化钴纳米颗粒的原位碳热还原。原位2p X射线吸收光谱（XAS）和RIXS测量在500、600和700℃下进行，其中四个一致的激发能量用于RIXS采集。在700℃还原后，XAS光谱呈现出类似钴金属的形状，而RIXS光谱揭示了少数的一氧化钴相。对XAS和RIXS数据的整体拟合揭示了金属和一氧化钴各自的贡献。我们表明，确定一氧化钴含量的相对精度从XAS结果中的约5.6%变为RIXS分析中的优于0.8%，这表明RIXS是在原位条件下追踪纳米颗粒氧化态的有用工具。我们确定了一个约为5的相对辐射率（）因子，该因子给出了CoO和Co金属中辐射衰变通道与非辐射通道相对强度的比值。
