The precise exploration and anticipation of the structure-activity relationship between catalysts and reactants remain crucial endeavors for catalysis scientists. Achieving this requires advanced catalysts and state-of-the-art characterization techniques to offer a thorough understanding of catalytic processes. We will give content of two aspects in the present talk: a recent scientific summary of our work and a brief introduction of our newly designed infrared spectroscopy instrument for future plans. Firstly, we employed a combination of density functional theory (DFT) and time-lapse scanning tunneling microscopy (STM) to study the behavior of CO adsorption on Rh 1 single atoms and Rh2 dimers supported by well-defined Fe 3 O4(001) single crystal. CO adsorption at Rh1 sites results exclusively in stable Rh 1CO monocarbonyls, because the Rh atom adapts its coordination to create a stable pseudosquare planar environment. Rh1(CO) 2 gem-dicarbonyl species are also observed, but these form exclusively through the breakup of Rh2 dimers via an unstable Rh 2(CO) 3 intermediate. Our results clearly show that the adsorption of reactants can have a strong influence on the structure of the system, and that CO exposure can be used to redisperse small clusters that form during reactions. Overall, this work provides new insights into the rational design of novel single-atom catalysts through the synthesis of dimer catalysts. In the second part, we would like to briefly report the progress of our infrared technique and some preliminary collected data on TiO2 system.