Pt/α-Al2O3表面氢气的吸附、解离和传质的计算  

Calculation of dissociation and transfer of hydrogen on Pt/α-Al2O3 surface

作　　者：李建飞 吴亚云 付笑盈 王冰[1] 周仕学[1] LI Jianfei;WU Yayun;FU Xiaoying;WANG Bing;ZHOU Shixue(College of Chemistry and Biological Engineering. Shandong University of Science and Technology,Qingdao 266590, China)

机构地区：[1]山东科技大学化学与生物工程学院,山东青岛266590

出　　处：《功能材料》2021年第1期1180-1184,共5页Journal of Functional Materials

基　　金：国家自然科学基金资助项目(21978156)。

摘　　要：基于第一性原理,研究了H2分子在α-Al2O3表面负载的Pt原子以及Pt4团簇上面的吸附、解离和传质。研究结果表明,Pt原子和Pt4团簇在α-Al2O3表面形成稳定的化学吸附。在H2分子的吸附过程中,H2分子吸附在Pt原子上,自发解离,形成Pt-H键。这一过程Pt原子提供电子,H原子得到电子,Pt与H发生电子云重叠,形成PtH2化合物。在单原子Pt上,H溢流到O原子上的能垒为1.46 eV,该过程强吸热,这说明H不容易溢流。形成PtH2化合物以后,Pt原子失去了吸附解离H2的作用。Pt4团簇可以吸附解离多个H2分子,H的最大溢流能垒为0.70 eV,该过程自发放热,远远低于单原子Pt上H的溢流能垒。原因在于Pt4团簇中Pt-Pt之间的强相互作用力分散了Pt-H之间的相互作用,H容易溢流下来。H在α-Al2O3表面从O原子到O原子的传质过程中,α-Al2O3表面的Al原子对H的传质有强阻碍作用,H不容易在α-Al2O3稳定的表面传质。Based on the first principles,the adsorption,dissociation and mass transfer of H2 molecules on the Pt atoms and Pt4 cluster supported surface ofα-Al2O3 were studied.The results show that,Pt atom and Pt4 cluster can form a relatively stable chemical adsorption onα-Al2O3 surfaces.In the adsorption process of H2 molecules,H2 molecules can be adsorbed on Pt atoms and dissociate to form Pt-H bonds.In this process,Pt atoms provide electrons and H atoms get electrons,then Pt and H overlap electron clouds to form PtH2 compounds.On single-atom Pt,the energy barrier of H overflowing to O atom is 1.46 eV.This process strongly absorbs heat,which shows that H is not easy to overflow.After the formation of PtH2 compounds,Pt atoms lose the role of adsorption and dissociation of H2.Pt4 cluster can adsorb and dissociate multiple H2 molecules,and the maximum overflow energy barrier of H is 0.70 eV.The overflow is a spontaneous,exothermic process,which is much lower than the overflow energy barrier of H on single-atom Pt.The reason is that the strong interaction between Pt-Pt in the Pt4 cluster disperses the interaction between Pt-H,and H is easy to overflow.During the mass transfer process of H from O atom to O atom on the surface ofα-Al2O3,the Al atoms on the surface ofα-Al2O3 have a strong hindrance to the mass transfer of H,and it is not easy for H to transfer on the stable surface ofα-Al2O3.

关 键 词：PT Α-AL2O3 单原子 团簇 氢传质 

分 类 号：TK91[动力工程及工程热物理]