Li Lin, Abild-Pedersen Frank, Greeley Jeff, Nørskov Jens K
SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University , 443 Via Ortega, Stanford, California 94305, United States.
SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States.
J Phys Chem Lett. 2015 Oct 1;6(19):3797-801. doi: 10.1021/acs.jpclett.5b01746. Epub 2015 Sep 10.
We present calculated adsorption energies of oxygen on gold and platinum clusters with up to 923 atoms (3 nm diameter) using density functional theory. We find that surface tension of the clusters induces a compression, which weakens the bonding of adsorbates compared with the bonding on extended surfaces. The effect is largest for close-packed surfaces and almost nonexistent on the more reactive steps and edges. The effect is largest at low coverage and decreases, even changing sign, at higher coverages where the strain changes from compressive to tensile. Quantum size effects also influence adsorption energies but only below a critical size of 1.5 nm for platinum and 2.5 nm for gold. We develop a model to describe the strain-induced size effects on adsorption energies, which is able to describe the influence of surface structure, adsorbate, metal, and coverage.
我们使用密度泛函理论给出了氧在含有多达923个原子（直径3纳米）的金和铂团簇上的计算吸附能。我们发现，团簇的表面张力会引起压缩，与在延展表面上的键合相比，这会削弱吸附质的键合。对于密排表面，这种效应最大，而在反应性更强的台阶和边缘处几乎不存在。这种效应在低覆盖率时最大，而在较高覆盖率时会减小，甚至改变符号，此时应变从压缩变为拉伸。量子尺寸效应也会影响吸附能，但仅在铂团簇临界尺寸1.5纳米及金团簇临界尺寸2.5纳米以下才会出现。我们开发了一个模型来描述应变诱导的尺寸效应如何影响吸附能，该模型能够描述表面结构、吸附质、金属和覆盖率的影响。
