In this section, we use simplified theoretical models of Rh single-atom catalysts on two reduced rutile TiO2(110) supports, TiO1.98 and TiO1.69, to compare the influence of these supports on the catalytic properties for CO2 activation, a key rate-determining step in the reverse water-gas shift (RWGS) reaction. We examined the canonical ensemble to identify the most stable binding site for Rh single atoms on these surfaces, without explicitly considering key adsorbates (e.g., H, O, OH, and CO) under reaction conditions in a grand canonical framework. Therefore, it is important to note that our study captures only the general trends in the catalytic effects of the two supports, rather than providing a highly accurate representation of their behavior under realistic conditions. A more precise understanding would require grand canonical sampling with relevant chemical potentials and further microkinetic simulations. This simplification particularly affects the energetics of the product state, where the dissociated O would be subject to facile desorption at relevant conditions.