添加稀土氧化物助剂的CeO2-ZrO2固溶体的储氧性及热稳定性研究

大多数工业催化剂都是在稳定的操作条件下进行的,然而汽车尾气净化催化剂却被暴露在大气中,使用条件经常变化,尤其是空燃比(A/F)的变化,直接影响了对氧敏感的三效催化剂的氧化和还原性能[1].CeO2则是一种具有储氧/释氧能力的催化材料,它作为助剂加入三效催化剂中,可在贫况下储存氧(以Ce4+存在)利于NOx的还原,在富况下释放氧(以Ce3+存在),利于HC、CO的氧化,从而提高了催化剂的活性.然而,CeO2 的储氧性通常局限在表面上,当温度超过400℃以上时,其比表面积降低从而引起储氧性能急剧下降,直接影响催化剂的性能和寿命.     

First-principles investigation on N/C co-doped CeO_2

The N and C doping effects on the crystal structures, electronic and optical properties of fluorite structure CeO_2 have been investigated using the first-principles calculation. Co-doping these two elements results in the local lattice distortion and volume expansion of CeO_2. Compared with the energy band structure of pure CeO_2, some local energy levels appear in the forbidden band, which may facilitate the light absorption. Moreover, the enhanced photo-catalytic properties of CeO_2 were explained through the absorption spectra and the selection rule of the band-to-band transitions.