‡Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
§Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
ACS Appl Mater Interfaces. 2015 Apr 22;7(15):7863-8. doi: 10.1021/am5073996. Epub 2015 Apr 9.
We have stabilized the iron oxide nanoparticles (NPs) of various sizes on layered carbon materials (Fe-oxide/C) that show excellent catalytic performance. From the characterization of X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), scanning transmission X-ray microscopy (STXM) and X-ray magnetic circular dichroism spectroscopy (XMCD), a strong interfacial interaction in the Fe-oxide/C hybrids has been observed between the small iron oxide NPs and layered carbon in contrast to the weak interaction in the large iron oxide NPs. The interfacial interaction between the NPs and layered carbon is found to link with the improved catalytic performance. In addition, the Fe L-edge XMCD spectra show that the large iron oxide NPs are mainly γ-Fe2O3 with a strong ferromagnetic property, whereas the small iron oxide NPs with strong interfacial interaction are mainly α-Fe2O3 or amorphous Fe2O3 with a nonmagnetic property. The results strongly suggest that the interfacial interaction plays a key role for the catalytic performance, and the experimental findings may provide guidance toward rational design of high-performance catalysts.
我们已经将各种尺寸的氧化铁纳米粒子（NPs）稳定在层状碳材料（Fe-oxide/C）上，这些材料表现出优异的催化性能。通过 X 射线吸收光谱（XAS）、X 射线发射光谱（XES）、扫描透射 X 射线显微镜（STXM）和 X 射线磁圆二色性光谱（XMCD）的表征，我们观察到在 Fe-oxide/C 杂化材料中，小氧化铁 NPs 与层状碳之间存在强烈的界面相互作用，而在大氧化铁 NPs 中则存在较弱的相互作用。研究发现，纳米颗粒与层状碳之间的界面相互作用与催化性能的提高有关。此外，Fe L 边 XMCD 谱表明，大氧化铁 NPs 主要是具有强铁磁性的γ-Fe2O3，而具有强界面相互作用的小氧化铁 NPs 主要是无磁性的α-Fe2O3 或非晶态 Fe2O3。这些结果强烈表明界面相互作用对于催化性能起着关键作用，实验结果可能为高性能催化剂的合理设计提供指导。
