Fung Victor, Wu Zili, Jiang De-En
Department of Chemistry , University of California , Riverside , California 92521 , United States.
Chemical Sciences Division and Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States.
J Phys Chem Lett. 2018 Nov 1;9(21):6321-6325. doi: 10.1021/acs.jpclett.8b02749. Epub 2018 Oct 22.
A new model of bonding between radical adsorbates and lattice oxygens is proposed that considers both the adsorbate-oxygen bonding and the weakening of the metal-oxygen bonds. Density functional calculations of SrMO perovskites for M being 3d, 4d, and 5d transition metals are used to correlate the bulk electronic structure with the surface-oxygen reactivity. Occupation of the metal-oxygen antibonding states, examined via the crystal orbital Hamilton population (COHP), is found to be a useful bulk descriptor that correlates with the vacancy formation energy of the lattice oxygen and its hydrogen adsorption energy. Analysis of density-of-states and COHP indicates that H adsorption energy is a combined result of formation of the O-H bond and the weakening of the surface metal-oxygen bond due to occupation of the metal-oxygen antibonding states by the electron from H. This insight will be useful in understanding the trends in surface reactivity of perovskites and transition-metal oxides in general.
提出了一种新的自由基吸附物与晶格氧之间的键合模型，该模型同时考虑了吸附物-氧键合和金属-氧键的弱化。对M为3d、4d和5d过渡金属的SrMO钙钛矿进行密度泛函计算，以将体电子结构与表面氧反应性相关联。通过晶体轨道哈密顿布居（COHP）研究发现，金属-氧反键态的占据是一个有用的体相描述符，它与晶格氧的空位形成能及其氢吸附能相关。态密度和COHP分析表明，H吸附能是O-H键形成以及由于H的电子占据金属-氧反键态而导致表面金属-氧键弱化的综合结果。这一见解将有助于理解一般情况下钙钛矿和过渡金属氧化物的表面反应性趋势。
