水分子在ZrCo(110)表面聚集与解离的理论研究

Theoretical Study of the Aggregation and Dissociation of Water Molecules on the ZrCo(110)Surface

储氚材料锆钴合金(ZrCo)与气体中的水分子发生氧化反应,会导致材料表面的毒化失活,对聚变堆的安全运行产生极大影响.本文利用基于密度泛函理论(DFT)的第一性原理计算方法,研究了不同水分子团簇在ZrCo(110)表面的吸附-解离行为.研究发现,6个水分子形成的水团簇在表面通过氢键作用形成环状的吸附构型,随着团簇尺寸的增大,由于表面空间效应,新增分子的吸附能逐渐减小,水团簇逐渐演变成复杂的双层水分子吸附构型;由于水团簇存在氢键作用,质子能够在不同水分子之间发生快速的转移.并且水分子容易在ZrCo(110)表面活性位点发生化学键断裂,其产物OH主要与表面Zr原子存在相互作用,而产物H吸附在Zr2Co空位.因此,氢键作用在水分子氧化腐蚀ZrCo(110)表面过程中扮演着非常重要的角色.

The oxidation reaction between zirconium cobalt alloy(ZrCo),as a tritium storage material,and gas water molecules usually leads to the poisoning and deactivation of the material surface,which greatly affects the safe operation of fusion reactors.In this article,first-principles calculation methods based on density functional theory(DFT)was employed to study the adsorption and dissociation behavior of various water molecule clusters on the ZrCo(110)surface.The result shows that 6H2O cluster forms a cyclic adsorption configuration on the surface through hydrogen bonding.As the cluster size increases,the adsorption energy of newly added molecule gradually decreases,and water clusters gradually evolve into complex double-layer water molecule adsorption configurations due to surface spatial effects.Moreover,protons can rapidly transfer between different water molecules by the hydrogen bonding in water clusters.On the other hand,water molecules are prone to chemical bond cleavage at the active sites on the ZrCo(110)surface,where the product OH mainly interacts with surface Zr atoms,while the product H adsorbs on Zr2Co threefold hollow sites.Therefore,hydrogen bonding plays a very important role in the oxidation and corrosion behavior of ZrCo(110)surface by water molecules.