Understanding the intrinsic synergistic mechanism between Pt-O-Ti interface sites and TiO₂ surface sites of Pt/TiO₂ catalysts in Fenton-like reaction

Identifying the active site of oxide-supported metal catalysts and revealing the intrinsic synergistic mechanism between metal and oxide support remain a large challenge. Herein, we report the identification and separation of the Pt-O-Ti interface and TiO₂ surface in Pt-TiO₂-based catalysts by depositing different thickness of TiO₂ shell with ∼0.4-nm micropores onto the surface of Pt/TiO₂ catalyst through atomic layer deposition (ALD). In the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by hydrogen peroxide (H₂O₂) process, the TiO₂ microporous shells can prevent the contact between TMB and embedded Pt clusters, but not delay the diffusion of H₂O₂. The heterolysis of H₂O₂ to •OH occurs on the Pt-O-Ti interface, and the generated •OH migrates to the TiO₂ surface to supplement the surface lattice oxygen, which sequentially oxidizes TMB to oxTMB. And the synergistic effect between Pt-O-Ti interface active sties and TiO₂ surface active sites can significantly improve the catalytic performance. Our study provides a guide for the understanding of the intrinsic synergistic mechanism between the metal and oxide support in the metal-oxide catalysts.