Designing bimetallic IrRu nanoparticles on oxygen-deficient WO3 for efficient NO reduction by CO

Abstract

In this work, WO₃ was used as a support to prepare noble metal-based IrRu/WO₃ catalysts for the CO selective catalytic reduction (CO-SCR) in oxygen-rich flue gas. The CO-SCR activity was promoted through the synergistic interaction between Ir and Ru, coupled with the tailored interface between oxygen-deficient WO₃ and the bimetallic IrRu nanoclusters. XRD and TEM results confirmed the formation of well-dispersed Ir–Ru nanoparticles, as well as a reduction-induced transformation of WO₃ to WO_2.92. Various techniques, along with DFT calculations, were employed to investigate the synergistic roles of Ir and Ru, as well as the contribution of the WO₃ support. The enhanced CO-SCR activity of IrRu/WO₃ was attributed to the electronic synergy between Ir and Ru, which stabilized Ir⁰ and facilitated NO activation, and the oxygen vacancies in WO₃ induced by the strong metal–support interaction (SMSI). These vacancies not only protected active metal sites but also generated reactive oxygen species that stabilize NO_x as nitrates. This work addresses the gap in understanding WO₃-supported IrRu bimetallic catalysts and provides new perspectives for designing efficient CO-SCR catalysts, setting the stage for further mechanistic and kinetic investigations.