Fabrication of CeO₂-MO (M = Cu, Co, Ni) composite yolk-shell nanospheres with enhanced catalytic properties for CO...

CeO₂-MO (M = Cu, Co, Ni) composite yolk-shell nanospheres with uniform size were fabricated by a general wet-chemical approach. It involved a non-equilibrium heat-treatment of Ce coordination polymer colloidal spheres (Ce-CPCSs) with a proper heating rate to produce CeO₂ yolk-shell nanospheres, followed by a solvothermal treatment of as-synthesized CeO₂ with M(CH₃COO)₂ in ethanol solution. During the solvothermal process, highly dispersed MO species were decorated on the surface of CeO₂ yolk-shell nanospheres to form CeO₂-MO composites. As a CO oxidation catalyst, the CeO₂-MO composite yolk-shell nanospheres showed strikingly higher catalytic activity than naked CeO₂ due to the strong synergistic interaction at the interface sites between MO and CeO₂. Cycling tests demonstrate the good cycle stability of these yolk-shell nanospheres. The initial concentration of M(CH₃COO)₂·xH₂O in the synthesis process played a significant role in catalytic performance for CO oxidation. Impressively, complete CO conversion as reached at a relatively low temperature of 145 °C over the CeO₂-CuO -2 sample. Furthermore, the CeO₂-CuO catalyst is more active than the CeO₂-CoO and CeO₂-NiO catalysts, indicating that the catalytic activity is correlates with the metal oxide. Additionally, this versatile synthesis approach can be expected to create other ceria-based composite oxide systems with various structures for a broad range of technical applications.