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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Probing the Surface Heterogeneity of Polycrystalline Zinc Oxide by Static Adsorption Microcalorimetry.2.The Adsorption of Carbon Monoxide
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Probing the Surface Heterogeneity of Polycrystalline Zinc Oxide by Static Adsorption Microcalorimetry.2.The Adsorption of Carbon Monoxide

机译：用静态吸附量热法研究多晶氧化锌的表面非均质性。2．一氧化碳的吸附

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The adsorption of CO on polycrystalline ZnO powder samples was investigated as a function of the pretreatment by applying static adsorption microcalorimetry and temperature-programmed desorption(TPD).Mainly weak adsorption sites were found to be present on the exposed ZnO surfaces but also a minor amount of highly active sites(>0.1mu nol/m2).On the majority sites,the adsorption of CO is weak,as reflected by the isotherms and the TPD profiles,with a maximum heat of adsorption of about 40 kJ/mol,which decreases with increasing coverage and also with an increasing amount of surface hydroxyl groups.The standard adsorption entropy is derived to amount to-102 J mol~(-1)K~(-1).These weak adsorption sites are hardly influenced by the pretreatment in flowing oxygen,hydrogen,or helium.On the highly active sites,as probed by small doses of CO in the calorimetric experiments,different exothermic(>100 kJ/mol)and endothermic surface reactions occur in addition to CO adsorption,depending on the gas atmosphere applied during the pretreatment.These results clearly indicate that the small amount of highly active sites accounts for the catalytic properties of ZnO.
机译：采用静态吸附量热法和程序升温脱附法研究了CO在多晶ZnO粉末样品上的吸附与预处理的关系，发现暴露的ZnO表面主要存在较弱的吸附位，但也有少量吸附位高活性位点（> 0.1mu nol / m2）。在大多数位点上，CO的吸附较弱，这由等温线和TPD曲线反映出来，最大吸附热为40 kJ / mol，这降低了标准吸附熵为-102 J mol〜（-1）K〜（-1）。这些弱吸附位几乎不受预处理的影响。流动的氧气，氢气或氦气。在高活性位点上，通过量热实验中的小剂量CO进行探测，除了CO吸附之外，还会发生不同的放热（> 100 kJ / mol）和吸热表面反应，具体取决于气体一种这些结果清楚地表明，少量的高活性位点说明了ZnO的催化特性。

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