Departamento de Química, Universidade Federal do Maranhão , Avenida dos Portugueses, 1966, CEP 65080-805, São Luís - MA, Brazil.
Instituto de Electroquímica, Universidad de Alicante , Ap. 99, E-03080, Alicante, Spain.
Langmuir. 2017 Jan 31;33(4):865-871. doi: 10.1021/acs.langmuir.6b03612. Epub 2017 Jan 20.
The knowledge about how CO occupies and detaches from specific surface sites on well-structured Pt surfaces provides outstanding information on both dynamics/mobility of CO and oxidation of this molecule under electrochemical conditions. This work reports how the potentiostatic growth of different coverage CO adlayers evolves with time on both cubic and octahedral Pt nanoparticles in acidic medium. Data suggest that during the growth of the CO adlayer, CO molecules slightly shift toward low coordination sites only on octahedral Pt nanoparticles, so that these undercoordinated sites are the first filled on octahedral Pt nanoparticles. Conversely, on cubic Pt nanoparticles, adsorbed CO behaves as an immobile species, and low coordinated sites as well as (100) terraces are apparently filled uniformly and simultaneously. However, once the adlayer is complete, irrespectively of whether the CO is oxidized in a single step or in a sequence of different potential steps, results suggest that CO behaves as an immobile species during its oxidation on both octahedral and cubic Pt nanoparticles.
关于 CO 如何占据和脱离结构良好的 Pt 表面上特定表面位置的知识，为 CO 的动力学/迁移性以及电化学条件下该分子的氧化提供了重要信息。本工作报道了在酸性介质中，不同覆盖度 CO 吸附层在立方和八面体 Pt 纳米粒子上电静位生长随时间的变化。数据表明，在 CO 吸附层的生长过程中，CO 分子仅在八面体 Pt 纳米粒子上略微向低配位位点移动，因此这些低配位位点首先在八面体 Pt 纳米粒子上被占据。相反，在立方 Pt 纳米粒子上，吸附的 CO 表现为非迁移性物种，低配位位点和（100）平台显然均匀且同时被填充。然而，一旦吸附层完全形成，无论 CO 是在单个步骤还是在一系列不同的电位步骤中被氧化，结果表明 CO 在八面体和立方 Pt 纳米粒子上氧化时都表现为非迁移性物种。
