Highly Active CuO x /SiO 2 Dot Core/Rod Shell Catalysts with Enhanced Stability for the Reverse Water Gas Shift Reaction.

Cu-based catalysts are highly active and selective for several CO ₂ conversion reactions; however, traditional monometallic Cu-based catalysts suffer poor thermal stability due to the aggregation of copper particles at high temperatures. In this work, we demonstrate a crystal engineering strategy to controllably prepare copper/silica (CuO _x /SiO ₂ ) catalysts for the reverse water gas shift reaction (RWGS) at high temperatures. We show that CuO _x /SiO ₂ catalysts derived from the in situ reduction of pure copper silicate nanotubes in a CO ₂ and H ₂ atmosphere exhibit superior catalytic activity with enhanced stability compared to traditional monometallic Cu-based catalysts for the RWGS at high temperatures. Detailed structural characterization reveals that there is a strong interaction between Cu and SiO ₂ in CuO _x /SiO ₂ catalysts, which produces more Cu ⁺ sites and smaller CuO _x nanoparticles. Moreover, CuO _x /SiO ₂ catalysts possess a unique dot core/rod shell structure, which could prevent the aggregation of Cu particles. This structural confinement effect, enhanced CO ₂ adsorption by Cu ⁺ , and small CuO _x nanoparticles presumably caused the catalyst's extraordinary activity with enhanced stability at high temperatures.