Dual active sites induced by selective modification of TiOx on Pt catalysts by atomic layer deposition for hydrogenation catalysis

Metal-support interactions (MSIs) critically influence the performance of oxide-supported metal catalysts, yet the intrinsic coupling between metal-oxide interface sites and electronically modified metal sites hampers clear identification of true active centers. Here, a Pt/Al₂O₃ catalyst is modified with TiO_x by atomic layer deposition. Based on the favorable lattice matching with Pt (111), TiO_x prefers to deposit onto the high-coordinated Pt atoms. The modified catalyst was used for selective hydrogenation of para-chloronitrobenzene. It is found that the selective deposition of TiO_x on Pt nanoparticles can construct dual active sites, including precisely regulated Pt-Ti interface sites and exposed low-coordinated Pt sites with electron loss. The optimized 30Ti-Pt/Al₂O₃ catalyst exhibits nearly twice the turnover frequency of Pt/Al₂O₃, together with excellent chemoselectivity and stability. Kinetic studies, in situ spectroscopic analysis, and density functional theory calculations demonstrate that H₂ is activated on exposed low-coordinated Pt sites and subsequently transferred to Pt-Ti interface sites with adsorbed nitro groups for the hydrogenation. This work provides fundamental insight into active-site differentiation in MSI-dominated catalysts and offers a general strategy for rational interface engineering.