Energetics of Adsorbed Methanol and Methoxy on Ni(111): Comparisons to Pt(111)
Energetics of Adsorbed Methanol and Methoxy on Ni(111): Comparisons to Pt(111)
复制标题
甲醇和甲氧基在Ni（111）和Pt（111）上吸附的能量学比较
DOI：
10.1021/acscatal.8b02992
复制
发表时间：
2018-11-01
期刊：
影响因子：
12.9
通讯作者：
Campbell, Charles T.
中科院分区：
文献类型：
--
作者：
Carey, Spencer J.;Zhao, Wei;Campbell, Charles T.
用单晶吸附量热法(SCAC)测定了甲醇分子在纯净Ni(111)上的吸附热和解离吸附在氧覆盖的Ni(111)上的吸附热。甲醇在氧覆盖的Ni(111)面上的解离吸附产生了吸附的甲氧基和羟基，其积分吸附热为-70。KJ/摩尔，覆盖0.25毫升。由此推算出该吸附甲氧基的生成热及其与Ni(111)键离解热分别为-233和250。KJ/m o l。分析了单齿甲酸盐和羟基对Ni(111)的键热，发现含氧化合物在Ni(111)面上的键热与其对应的气相氢键解离热之间呈线性趋势，斜率为1，与铂(111)的趋势相似，但与69kJ/mol更强。我们还比较了我们的实验测量的吸附甲醇和吸附甲氧基的能量与密度泛函理论(DFT)计算和周期边界条件的文献。这些能量值和趋势有助于阐明在涉及吸附的含氧物的反应中，金属表面之间的选择性、反应速率和活性差异。
The heats of adsorption of methanol molecularly adsorbed on clean Ni(111) and dissociatively adsorbed on oxygen-precovered Ni(111) were measured by single-crystal adsorption calorimetry (SCAC). The dissociative adsorption of methanol on oxygen-precovered Ni(111) produces adsorbed methoxy and hydroxyl, resulting in an integral heat of adsorption of -70. kJ/mol at a coverage of 0.25 ML. From this, the heat of formation of this adsorbed methoxy and the dissociation enthalpy of its bond to Ni(111) are estimated to be -233 and 250. kJ/mol, respectively. Analyzing previously measured bond enthalpies of monodentate formate and hydroxyl to Ni(111), we find a linear trend with a slope of 1 between the bond enthalpies of oxygenates to the Ni(111) surface and their corresponding gas-phase hydrogen-ligand bond dissociation enthalpies, similar to the trend for Pt(111) but similar to 69 kJ/mol stronger. We also compare our experimentally measured energetics for adsorbed methanol and adsorbed methoxy with density functional theory (DFT) calculations with periodic boundary conditions literature. These energetic values and trends help clarify selectivity, reaction rate, and activity differences between metal surfaces in reactions involving adsorbed oxygenates.