Highly Active CuOx/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 (CuOx/SiO2) catalysts for the reverse water gas shift reaction (RWGS) at high temperatures. We show that CuOx/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 CuOx/SiO2 catalysts, which produces more Cu+ sites and smaller CuOx nanoparticles. Moreover, CuOx/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 CuOx nanoparticles presumably caused the catalyst's extraordinary activity with enhanced stability at high temperatures.