还原和氧化的TbO <sub><i>x</i></sub>（111）表面上的甲醇吸附和氧化,The Journal of Physical Chemistry C

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还原和氧化的TbO _x（111）表面上的甲醇吸附和氧化
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-12-13 00:00:00 , DOI: 10.1021/acs.jpcc.6b09908
A. Schaefer ₁ , W. Cartas ₂ , R. Rai ₂ , M. Shipilin ₁ , L. R. Merte ₁ , E. Lundgren ₁ , J. F. Weaver ₂

Affiliation

我们使用程序升温反应光谱（TPRS）和基于同步辐射的光电子能谱（PES）研究了甲醇（CH ₃ OH）在Tb ₂ O ₃（111）和TbO ₂（111）薄膜上的吸附和氧化生长在Pt（111）上。我们发现，甲醇主要通过分子过程和重组过程从Tb ₂ O ₃表面解吸，并且相对少量的吸附甲醇（<20％）脱氢成CH ₂ O和H ₂ O，这些物质解吸的程度约为160-200 nm。 300K。氧化氧化bia膜可提高表面反应性，因为大约50％的甲醇被吸附在TbO _2上在TPRS期间，主要被氧化为CH ₂ O和水以及在600 K附近解吸的CO ₂。产物产率的定量表明，在TPRS期间，通过与吸附的CH ₃ OH反应，除去了由Tb ₂ O ₃氧化为TbO ₂引起的所有多余的表面O原子。在任何条件下，我们都没有检测到CO或H _2的产生。PES测量表明，在低至140 K的温度下，TbO _x表面上会形成几种吸附的中间体，主要包括甲氧基（CH ₃ O-）以及少量的更易氧化的物质，被认为是CH ₂ O _2。或CHO ₂。随表面温度变化而收集的XPS光谱提供了证据，表明在低于400 K的温度下，吸附的CH ₃ O–基团是CH ₂ O和CH ₃ OH形成的主要中间体，而氧化程度更高的物质是CH ₂ ö形成，但经历完全氧化上TBO ₂在温度高于450 K.的TBO的高反应性₂与被所述Tb中的氧化过程中产生的不稳定的氧原子的存在表面相关因素₂ ö ₃膜。

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Methanol Adsorption and Oxidation on Reduced and Oxidized TbOx(111) Surfaces

We used temperature-programmed reaction spectroscopy (TPRS) and synchrotron-radiation-based photoelectron spectroscopy (PES) to investigate the adsorption and oxidation of methanol (CH₃OH) on Tb₂O₃(111) and TbO₂(111) thin films grown on Pt(111). We find that methanol mainly desorbs from the Tb₂O₃ surface through both molecular and recombinative processes and that a relatively small amount of adsorbed methanol (<20%) dehydrogenates to CH₂O and H₂O with these species desorbing between about 160 and 300 K. Oxidation of the terbia film enhances the surface reactivity as ∼50% of the adsorbed methanol on TbO₂ oxidizes to mainly CH₂O and water as well as CO₂ that desorbs near 600 K during TPRS. Quantification of the product yields suggests that all of the excess surface O atoms, resulting from oxidation of Tb₂O₃ to TbO₂, are removed during TPRS by reaction with adsorbed CH₃OH. We did not detect CO or H₂ production under any conditions. PES measurements show that several adsorbed intermediates form on the TbO_x surfaces at temperatures as low as 140 K, including mainly methoxy (CH₃O−) as well as smaller quantities of a more oxidized species, thought to be either CH₂O₂ or CHO₂. XPS spectra collected as a function of the surface temperature provide evidence that the adsorbed CH₃O– groups serve as the main intermediate for both CH₂O and CH₃OH formation at temperatures below 400 K, while the more oxidized species is a spectator to CH₂O formation but undergoes complete oxidation on TbO₂ at temperatures above 450 K. The high reactivity of the TbO₂ surface correlates with the presence of labile oxygen atoms that are generated during oxidation of the Tb₂O₃ film.

更新日期：2016-12-13

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