The Strong Interaction Between CuOx and CeO2 Nanorods Enhanced Methanol Synthesis Activity for CO2 Hydrogenation

The Cu/CeO2-nanopolyhedrals and pure Cu/CeO2-nanorods with different sizes were synthesized for CO2 hydrogenation to methanol. With increasing the percentage composition of CeO2 nanorods, the surface concentrations of Cu+, Ce3+ and oxygen vacancies were gradually enhanced. However, the amount of surface Cu+ species and oxygen vacancies would be decreased instead if the size of pure CeO2 nanorods was too large. The variation tendency of catalytic performance for CO2 hydrogenation to methanol was well consistent with that of Cu+ species and oxygen vacancies. Cu/CeO2 nanorods with small size exhibited the strongest interaction in Cu-CeO2 interface and the highest methanol production activity among all Cu/CeO2 nano-catalysts. The small size of CeO2-nanorods obtained at NaOH concentration of 10 mol/L, hydrothermal temperature of 80 degrees C and hydrothermal time of 24 h showed the best catalytic performance (X-CO2 = 5.8%, S-CH3OH= 92.0%, Y-CH3OH = 5.3%) at 280 degrees C and 3 MPa. The stronger interaction accelerated the charge transfer between CuOx species and CeO2 nanorods, which produced the larger amount of surface Cu+ species and oxygen vacancies. The synergistic effect between reduced Cu species and oxygen vacancies improved methanol selectivity and was responsible for CO2 hydrogenation to methanol. [GRAPHICS] .