Morphology and Crystal Plane Effects of Ceria Nanocrystals for Selective Catalytic Reduction of NO with NH3

Nitrogen oxides (NOX) are one of the major sources of air pollution and can cause serious environmental issues. Herein, a series of CeO2 nanomaterials with different morphologies, such as nanorods, nanopolyhedrons, and spindles, have been designed and fabricated via a facile hydrothermal method as efficient catalysts for the selective catalytic reduction of NOX with NH3. The as-prepared catalysts were characterized by means of scanning electron microscopy, transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, Fourier transform infrared spectrometry, and temperature-programmed desorption. The high percentage of the exposed (100) plane, together with the small crystalline size of the CeO2 nanorods, led to more oxygen absorbed on their surface, which accelerated the adsorption and activation of NO and NH3, and lowered the apparent activation energy. Therefore, CeO2 nanorods exhibited the highest catalytic activity across the whole temperature range (150–450°C) and obtained 94% NO conversion at 450°C with high N2 selectivity.