Selective electrooxidation of 2-propanol on Pt nanoparticles supported on Co3O4: an in-situ study on atomically defined model systems
Selective electrooxidation of 2-propanol on Pt nanoparticles supported on Co3O4: an in-situ study on atomically defined model systems
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DOI：
10.1088/1361-6463/abd9ea
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发表时间：
2021-04
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通讯作者：
Tian Yang;Maximilian Kastenmeier;Michal Ronovský;Lukáš Fusek;T. Skála;Fabian Waidhas;M. Bertram;N. Tsud;P. Matvija;K. Prince;V. Matolín;Zhi Liu;V. Johánek;J. Mysliveček;Y. Lykhach;O. Brummel;J. Libuda
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作者：
Tian Yang;Maximilian Kastenmeier;Michal Ronovský;Lukáš Fusek;T. Skála;Fabian Waidhas;M. Bertram;N. Tsud;P. Matvija;K. Prince;V. Matolín;Zhi Liu;V. Johánek;J. Mysliveček;Y. Lykhach;O. Brummel;J. Libuda
2-丙醇和它的脱氢对应物丙酮可以用作可充电的电燃料。该概念涉及在燃料电池中将2-丙醇选择性氧化为丙酮，并在封闭循环中将丙酮逆催化氢化为2-丙醇。研究了超高真空条件下制备的复合型Pt/Co 3 O 4（111）电催化剂对异丙醇的电催化氧化。在碱性介质（pH 10，磷酸盐缓冲液）中，用电化学红外反射吸收光谱和离位浮现同步辐射光电子能谱研究了模型电催化剂的电催化行为，并与Pt（111）和Co 3 O 4（111）电极在类似条件下的电催化行为进行了比较.我们发现Co_3O_4（111）薄膜在电化学条件下（0.3-1.1 VRHE）对异丙醇的电化学氧化是不活泼的。2-丙醇在Pt（111）上容易发生电化学氧化，在0.4VRHE的起始电位下产生丙酮。该反应途径不涉及CO，但产生强烈吸附的丙酮物种，导致部分中毒的表面网站。在Pt/Co_3O_4（111）电催化剂上，我们观察到不同的金属载体相互作用和与金属/氧化物界面电荷转移相关的颗粒尺寸效应。我们发现，超小Pt颗粒（约1 nm及以下）由部分氧化的Pt δ +物种组成，其对2-丙醇氧化显示出较小的活性。相比之下，常规Pt颗粒（几nm的颗粒尺寸）主要是金属的并且对2-丙醇氧化显示出高活性。
2-Propanol and its dehydrogenated counterpart acetone can be used as a rechargeable electrofuel. The concept involves selective oxidation of 2-propanol to acetone in a fuel cell coupled with reverse catalytic hydrogenation of acetone to 2-propanol in a closed cycle. We studied electrocatalytic oxidation of 2-propanol on complex model Pt/Co3O4(111) electrocatalysts prepared in ultra-high vacuum and characterized by scanning tunneling microscopy. The electrocatalytic behavior of the model electrocatalysts has been investigated in alkaline media (pH 10, phosphate buffer) by means of electrochemical infrared reflection absorption spectroscopy and ex-situ emersion synchrotron radiation photoelectron spectroscopy as a function of Pt particle size and compared with the electrocatalytic behavior of Pt(111) and pristine Co3O4(111) electrodes under similar conditions. We found that the Co3O4(111) film is inactive towards electrochemical oxidation of 2-propanol under the electrochemical conditions (0.3–1.1 VRHE). The electrochemical oxidation of 2-propanol readily occurs on Pt(111) yielding acetone at an onset potential of 0.4 VRHE. The reaction pathway does not involve CO but yields strongly adsorbed acetone species leading to a partial poisoning of the surface sites. On model Pt/Co3O4(111) electrocatalysts, we observed distinct metal support interactions and particle size effects associated with the charge transfer at the metal/oxide interface. We found that ultra-small Pt particles (around 1 nm and below) consist of partially oxidized Pt δ + species which show minor activity towards 2-propanol oxidation. In contrast, conventional Pt particles (particle size of a few nm) are mainly metallic and show high activity toward 2-propanol oxidation.