We present a comprehensive mechanistic study on the highly tunable selectivity over In x /ZrO2 catalysts in CO2 hydrogenation. By variation of the indium loading between 0.1 and 5 wt %, either an admirable selectivity to methanol of 70–80% or up to 80% selectivity to CO could be obtained in the temperature range of 250–280 °C. It is shown that the shift in the product spectrum is related to the synergy between indium species and the zirconia substrate through variable interfacial structures. Zirconia-modulated crystalline In2O3, which prevails for indium loadings between 2.5 and 5 wt %, could enhance stepwise hydrogenation of *HCOO, leading to *H3CO and finally methanol due to the suitable bonding strengths of *HCOO and *H3CO. Regarding CO, evidence has been provided that the synergistic effect between adjacent indium and zirconia sites is indispensable for the entire catalytic cycle. *HCOO is formed at the indium–zirconia interfaces and decomposes to CO subsequently. Highly dispersed InO x dominating for loadings below 0.5 wt % features an enormous indium–zirconia interface and suppresses hydrogenation ability for *HCOO, thus favoring the generation of CO. The study provides fundamental insights into the mechanism of CO2 conversion and reaction pathway tuning over oxide catalytic systems.

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.

The reverse water–gas shift (RWGS) reaction is an initial and essential step for CO2 hydrogenation. In this study, Cu- and K-modified iron oxide catalysts were investigated with a series of in/ex-situ characterization techniques, including in situ XRD, in situ Raman, in situ DRIFTS quasi in situ XPS, quasi in situ HS-LEIS, H2-TPR, CO2-TPD, and TPSR. The surface structure of the catalyst is found to strongly depend on the presence of Cu and K, leading to diverse reducibility and basicity. Adding K to the iron-based catalyst alters the reaction from a redox pathway that proceeds on surface redox sites to an associative pathway that proceeds on surface redox and basic sites. Metallic Cu facilitates hydrogen dissociation and promotes both mechanisms by either boosting surface vacancy sites or supplying abundant surface hydrogen atoms. These findings would be beneficial for the rational design of CO2 hydrogenation catalysts.