TiO2-facet-dependent effect on methane combustion over Ir/TiO2 catalysts

Engineering the morphology of the support is effective in tuning the redox properties of active metals for efficient catalytic methane combustion via tailoring the metal-support interaction. Herein, uniform Ir nanoparticles supported on anatase TiO2 with different morphologies predominantly exposing {100}, {101}, and {001} planes were synthesized and tested for methane combustion. The CH4 catalytic activity shows a remarkable TiO2-facet-dependent effect and follows the order of Ir/TiO2-{100} > Ir/TiO2-{101} >> Ir/TiO2-{001}. Detailed characterizations and DFT calculations reveal that compared with Ir-TiO2-{101} and Ir-TiO2-{001} interfaces, the superior Ir-TiO2-{100} interface facilitates the generation of electron-rich Ir species through more profound charge transfer from TiO2-{100} to Ir atoms. The electron-rich Ir structure, featuring abundant defect oxygen vacancies, significantly enhances the redox properties of active Ir species and reduces the activation energy for breaking the initial C-H bond in CH4, resulting in the superior catalytic activity for methane combustion. These findings deepen fundamental insights into the TiO2-facet-dependent reactivity of different Ir/TiO2 nanomaterials in methane oxidation and pave the way for designing efficient Ir-based methane oxidation catalysts. (c) 2025, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.