Active Sites Identification on Defect‐Engineered TiO2${\rm TiO}_2$ Surfaces for Ethylene Hydrogenation via DFT and Microkinetics

Abstract Previous combined theoretical and experimental studies validate that defect induction can enhance ethylene () adsorption ability on the surface, which also exhibits excellent catalytic performance for acetylene‐to‐ethylene hydrogenation. However, there is a lack of systematic studies to further understand the mechanism of ethylene () hydrogenation into ethane (). Using density functional theory (DFT) and mean‐field microkinetic simulations (MKS), herein, we investigated hydrogenation on oxygen‐deficient rutile (110) and anatase (101) surfaces. Among the studied defect sites, the sub‐layer O‐vacancy in rutile and the 2‐coordinated oxygen () vacancy in anatase showed the highest catalytic activity. Anatase exhibited stronger binding and a lower kinetic barrier (0.97 eV) for the rate‐determining step (* *) compared to rutile. The maximum turnover frequency (TOF) on anatase reached 66 at 550 K. Additional MKS‐derived insights, including degree of rate control coefficients, apparent activation energies, species coverages, and reaction orders, elucidate the origins of catalytic activity, highlighting anatase as the more efficient surface for hydrogenation.