Understanding of dynamic structure of active sites is of paramounti mportance for rational design of industrialc atalysts. This work revealed the structure evolution of iron active phases for CO 2 hydrogenation over iron-based catalysts. With a combination of operando Ramans pectroscopy and X-ray Diffraction coupled with online gas chromatography,t he panoramic structure evolution of iron oxides (a-Fe 2 O 3 and g-Fe 2 O 3 ) during activation and CO 2 hydrogenation were elaborated, that is, a-

CeO 2 nanorods supported Co−CoO x catalysts showed high selectivity for higher alcohol synthesis (HAS) from syngas. The selectivity has found to increase with lowering the Co loadings, and the value over Co 1 /CeO 2 (19.86%) is twice higher than that over Co 5 /CeO 2 (8.67%).The active sites at the interfaces between Co 0 and CoO x , or to say, Co−CoO x pairs, have evidenced to be responsible for HAS. The strong metal−support interactions between Co and CeO 2 retard the reduction of CoO x and stabilize the intermediates such as CO−Co δ+ . Likely, CO favors dissociating on the metallic Co surface to form CH x species, while CO is associatively activated on Co δ+ sites. Moreover, the structure evolution of the Co−CoO x interface was revealed during calcination, reduction, and reaction using in situ X-ray diffraction (XRD), in situ Raman spectroscopy, X-ray absorption spectroscopy (XAS), and in situ diffuse reflectance infrared fourier transform spectroscopy (CO-DRIFTS). The structure−performance relationship of HAS over Co/CeO 2 was proposed.

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