NO双分子在Cu2O(111)面吸附与解离的理论研究

采用广义梯度密度泛函理论结合周期平板模型方法, 在DNP基组下, 研究了NO双分子在三重态和单重态两种电子组态下在Cu2O(111)完整表面的吸附情况. 考虑了Cu+(NO)(NO)、Cu+(NO)(ON)及Cu+(ON)(ON)这三种构型, 计算了它们的吸附能和Mulliken电荷, 分析并预测了吸附后可能产生的物种. 结果表明, 当两个NO分子都以O端吸附在Cu2O(111)表面时即Cu+(ON)(ON)构型, N—N键长很短, 只有124.4 pm, 吸附的两个NO分子形成了二聚体形式, 这种吸附构型有利于进一步离解产生N2或N2O并形成Cu-O表面物种.

Theoretical Studies of the Adsorption and Dissociation of Two NO Molecules on Cu2O(111) Surface

The adsorption and dissociation of two NO molecules on Cu2O(111) surface have been studied with periodic slab model by DFT method using the generalized gradient approximation(GGA) with the Perdew-Burke-Emzerhof(PBE) exchange-correlation functional. Three kinds of structures, Cu (NO)(NO), Cu (NO)(ON), and Cu (ON)(ON), with singlet and triplet states, were considered. Their corresponding adsorption energies and Mulliken charges were calculated. The calculated results indicate that in the optimized Cu (ON)(ON) configuration, two adsorbed NO molecules form a dimeric species with a much shorter N-N bond length(about 124.4 pm). Such a configuration contributes to the dissociation of NO to Cu-O surface species, with elimination of N2 or N2O.