制备方法对Nd2O3上过氧物种光诱导生成的影响

摘要

分别采用水解、水热和燃烧法制备了三种主要物相均为立方Nd2O3的样品.以325 nm激光为激发源,在室温和空气气氛下对上述样品上过氧物种的光诱导生成情况进行了比较考察.经Raman光谱仪的激光束照射后,三种样品上均可检测到过氧物种的生成,但燃烧法制备的样品上过氧的生成速率显著大于其他两种样品.O2-和CO2-TPD(程序升温脱附)的表征结果表明,与水解和水热法制备的立方Nd2O3相比,燃烧法制备的样品表面含有更多的低配位晶格氧物种,晶格氧的碱性也更强,因而更有利于在光诱导下与分子氧反应生成过氧物种.%Three Nd2O3 samples with cubic phase being the main component phase,denoted as Nd2O3-H,Nd2O3-HT,and Nd2O3-C,were synthesized by hydrolysis,hydrothermal,and combustion methods,respectively.A comparative study of the photo-induced formation of peroxide species on the three Nd2O3 samples was carried out using Raman spectroscopy with a 325 nm laser as the excitation source.After irradiation with the laser of the Raman spectrometer at room temperature in air,peroxide species was detected in all Nd2O3 samples.However,the rate of peroxide formation over Nd2O3-C was much greater than that over the other two samples.This observation can be explained by the differences in the structure and basicity of the surface lattice oxygen (O2-) species of the samples.As evidenced by the results of O2-and CO2-temperature-programmed desorption (TPD) characterizations,the Nd2O3-C sample contains greater number of surface lattice oxygen (O2-) species with low coordination numbers than the other two samples.Moreover,the basicity of the surface O2-species in Nd2O3-C is stronger than that in the Nd2O3-H and Nd2O3-HT samples.Both these factors are in favor of the reaction of lattice oxygen with molecular oxygen to generate peroxide species under photo irradiation.