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NiFe‐based electrocatalysts have attracted great interests due to the low price and high activity in oxygen evolution reaction (OER). However, the complex reaction mechanism of NiFe‐catalyzed OER has not been fully explored yet. Detection of intermediate species can bridge the gap between OER performances and catalyst component/structure properties. Here, we performed label‐free surface‐enhanced Raman spectroscopic (SERS) monitoring of interfacial OER process on Ni3FeOx nanoparticles (NPs) in alkaline medium. By using bifunctional Au@Ni3FeOx core‐satellite superstructures as Raman signal enhancer, we found direct spectroscopic evidence of intermediate O‐O− species. According to the SERS results, Fe atoms are the catalytic sites for the initial OH− to O‐O− oxidation. The O‐O− species adsorbed across neighboring Fe and Ni sites experiences further oxidation caused by electron transfer to NiIII and eventually forms O2 product. [ABSTRACT FROM AUTHOR]

This work reports on an assembling–calcining method for preparing gold–metal oxide core–satellite nanostructures, which enable surface‐enhanced Raman spectroscopic detection of chemical reactions on metal oxide nanoparticles. By using the nanostructure, we study the photooxidation of Si−H catalyzed by CuO nanoparticles. As evidenced by the in situ spectroscopic results, oxygen vacancies of CuO are found to be very active sites for oxygen activation, and hydroxide radicals (*OH) adsorbed at the catalytic sites are likely to be the reactive intermediates that trigger the conversion from silanes into the corresponding silanols. According to our finding, oxygen vacancy‐rich CuO catalysts are confirmed to be of both high activity and selectivity in photooxidation of various silanes. [ABSTRACT FROM AUTHOR]