NO在Ir(110)表面吸附和解离反应的泛函密度理论

采用密度泛函理论(DFT)和周期性平板模型,考察NO在Ir(110)表面上的吸附、解离及N2生成机理.计算结果表明:NO以N端向下在顶位吸附为最稳定的吸附方式,其次是短桥位,空位吸附最不稳定;顶位吸附的NO在表面存在2条解离通道:1)直接解离通道;2)由初始态扩散到短桥位,继而发生N—O键断裂生成N原子和O原子,是NO在表面解离的主要通道;解离后的N原子经联短桥位共吸附态发生N—N聚合反应生成N2,在表面共存的O原子促进了N2的生成,与实验结果相符.

Density Functional Theory of NO Adsorption and Dissociation on Ir(110)Surface

Density functional theory and periodic slab model were adopted to systemically study NO adsorption, dissociation and N₂ formation on Ir(110) surface. The results show that the most of stable sites are the top sites with the nitrogen bonding to Ir atoms, the short bridge sites are less stable and the hollow sites are the least of all. There are two paths for the dissociation of NOadsorbed on the top sites: One is direct dissociation; and the otheris diffusion from top site to short bridge site firstly and then dissociation. The results of potential energy surface show that the second path is more favorable than the first one, and is the primary path for NO dissociation. Two N atoms from the dissociated NO form a di short bridge structure torecombine into N₂. In addition, the pre dosed O atom enhances the N atoms combination reaction, which is consistent well with experiment result.