Mesoporous mesocrystal Ce1−xZrxO2 with enhanced catalytic property for CO conversion

Novel mesoporous mesocrystal Ce1−xZrxO2 was synthesized using acetate salt as inorganic species and P123 as surfactant. Transmission electron microscopy reveals that the wall framework consists of a single phase based on the face-centered cubic CeO2 and the nanocrystals are highly oriented with the crystal axis [001] parallel to the pore channel if the Zr4+ molar fraction x is 0.3 or less. However, when the Zr4+ molar fraction is larger than 0.3, a mixture of cubic and tetragonal phases forms and the preferential crystal orientation disappears as revealed by XRD and Raman measurements. The formation mechanism is ascribed to the oriented attachment following the manner of coherent interface. The single phase solid solution at Zr4+ molar fraction 0.3 demonstrates the best catalytic performance for CO conversion due to the unique mesoporous mesocrystal structure with dominant exposure of highly active {200} planes and an enhanced redox property caused by adequate Zr4+ incorporation.

Structure of mesoporous mesocrystal CeO2 with the crystal axis [001] parallel to the pore channel and its phase evolution with various molar fraction of Zr dopant (a) x=0, (b) x=0.2, (c) x=0.3, (d) x=0.5, and (e) x=0.8.Figure optionsDownload as PowerPoint slide