Tailoring Ir-FeOx interactions and catalytic performance in preferential oxidation of CO in H2 via the morphology engineering of anatase TiO2 over Ir-FeOx/TiO2 catalysts

Abstract

Ir-FeOx/TiO2 catalysts with both Ir and Fe contents of ∼1% wt. employing anatase TiO2 nanocrystals predominantly exposing either {100}, {101}, or {001} facets as the support were prepared and a comprehensive study was conducted on their interactions in pairs that are strongly dependent on the TiO2 morphology. The strongest FeOx-TiO2 interactions occurred over TiO2{001} support while TiO2{101} support contributes to the strongest Ir-TiO2 and Ir-FeOx interactions. Catalytic performance of the Ir-FeOx/TiO2 catalysts in preferential oxidation of CO in H2 is not only affected by the CO reactivity, but also determined by the Ir-FeOx interfaces. Ir-FeOx/TiO2{101} catalyst exhibits the highest CO conversion and best O2 selectivity over the three Ir-FeOx/TiO2 catalysts, which could be ascribed to stronger Ir-FeOx interactions that contribute to the enhancement of a H-spillover effect and subsequently facilitate the transformation of surface carbonaceous intermediates into CO2. These results add the versatility of the morphology engineering strategy in tailoring the structures and catalytic performance of oxide-based catalysts, and broaden the concept of morphology-dependent catalysis of oxide-based nanocrystal catalysts.