Template preparation of nanoscale CexFe1-xO2 solid solutions and their catalytic properties for ethanol steam reforming

High-surface-area CexFe1-xO2 solid solutions about 5 nm in size have been successfully prepared by using ultrahigh surface area carbon material as template and cerium and iron nitrates as oxide precursor. The obtained materials were characterized by means of N-2 physisorption, X-ray diffraction, Raman spectroscopy, electron paramagnetic resonance, transmission electron microscopy and energy dispersive X-ray spectroscopy. The redox and catalytic properties of the nanoscale CexFe1-xO2 solid solutions were also evaluated by temperature-programmed reduction and ethanol steam reforming. The results confirm the formation of the nanoscale CexFe1-xO2 cubic phase solid solutions with fluorite structure, and the process of Ce4+ substitution by Fe3+ gradually from the surface to the bulk of CeO2. A small addition of Fe into CeO2 resulted in a remarkable increase in the surface area and oxygen vacancy concentration, and decreased the particle size of the solid solution, while further Fe addition decreased the surface area and vacancy concentration of the solid solution, and increased the particle size of the solid solution. The results from temperature-programmed reduction show that addition of Fe into CeO2 not only promotes the reduction of CeO2, but also increases the oxygen vacancy concentration. The CexFe1-xO2 solid solutions show significant catalytic activity toward ethanol steam reforming with above 64% selectivity to hydrogen at 550 degrees C. The Ce0.90Fe0.10O2 sample presents superior activity and selectivity to hydrogen compared to CeO2, Fe2O3 and other solid solutions. The findings show that the carbon template route may be of great potential in synthesis of other solid solutions, and the CexFe1-xO2 solid solutions are potential materials for oxygen storage and ethanol steam reforming.