Highly Active CuO_x/SiO₂ 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 CO₂ 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/SiO₂) catalysts for the reverse water gas shift reaction (RWGS) at high temperatures. We show that CuO_x/SiO₂ catalysts derived from the in situ reduction of pure copper silicate nanotubes in a CO₂ and H₂ 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 SiO₂ in CuO_x/SiO₂ catalysts, which produces more Cu⁺ sites and smaller CuO_x nanoparticles. Moreover, CuO_x/SiO₂ catalysts possess a unique dot core/rod shell structure, which could prevent the aggregation of Cu particles. This structural confinement effect, enhanced CO₂ adsorption by Cu⁺, and small CuO_x nanoparticles presumably caused the catalyst's extraordinary activity with enhanced stability at high temperatures.