Harnessing metal-support interaction on Pt/TiO2 catalysts for oxygen vacancy engineering via H2 reduction toward low-temperature ethylene oxidation

Abstract

The Mars-van Krevelen (MvK) mechanism is widely recognized for enabling ethylene oxidation over Pt-oxide catalysts, which plays a key role in fruit and vegetable preservation. However, whether interfacial engineering can effectively promote low-temperature ethylene removal remains unclear. Herein, we systematically tuned the metal-support interaction in 2 % Pt/TiO₂ catalysts via hydrogen reduction at different temperatures to construct a series of catalysts with distinct structural and electronic properties. Structural characterizations including HR-TEM and CO chemisorption revealed that increased reduction temperature led to progressive TiO₂ encapsulation of Pt nanoparticles, decreasing Pt dispersion and altering the surface geometry. Meanwhile, XPS and H₂-TPR analyses confirmed the generation of Ti³⁺ species and surface oxygen vacancies, both of which increased with reduction temperature. Kinetic studies revealed a bifunctional mechanism in which metallic Pt served as the primary site for ethylene activation, while oxygen vacancies facilitated O₂ dissociation and functioned as the rate-determining step. Catalytic evaluation demonstrated that an optimal balance between Pt dispersion and oxygen vacancy concentration enabled stable and efficient ethylene conversion under ambient conditions. This study provides a mechanistic basis to manipulate metal-support interactions and engineer bifunctional active sites, offering valuable guidance for the rational design of low-temperature oxidation catalysts in practical ethylene removal applications.