Sheng Tian, Lin Wen-Feng, Sun Shi-Gang
Collaborative Innovation Centre of Chemistry for Energy Materials, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, 361005, China.
Department of Chemical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK.
Phys Chem Chem Phys. 2016 Jun 1;18(22):15304-11. doi: 10.1039/c6cp02198k.
Electroreduction of CO2 to hydrocarbons on a copper surface has attracted much attention in the last few decades for providing a sustainable way for energy storage. During the CO2 and further CO electroreduction processes, deoxygenation that is C-O bond dissociation, and hydrogenation that is C-H bond formation, are two main types of surface reactions catalyzed by the copper electrode. In this work, by performing the state-of-the-art constrained ab initio molecular dynamics simulations, we have systematically investigated deoxygenation and hydrogenation reactions involving two important intermediates, COHads and CHOads, under various conditions of (i) on a Cu(100) surface without water molecules, (ii) at the water/Cu(100) interface and (iii) at the charged water/Cu(100) interface, in order to elucidate the electrochemical interfacial influences. It has been found that the electrochemical interface can facilitate considerably the C-O bond dissociation via changing the reaction mechanisms. However, C-H bond formation has not been affected by the presence of water or electrical charge. Furthermore, the promotional roles of an aqueous environment and negative electrode potential in deoxygenation have been clarified, respectively. This fundamental study provides an atomic level insight into the significance of the electrochemical interface towards electrocatalysis, which is of general importance for understanding electrochemistry.
在过去几十年中，铜表面上二氧化碳电还原为碳氢化合物因提供了一种可持续的能量存储方式而备受关注。在二氧化碳及后续的一氧化碳电还原过程中，脱氧（即碳 - 氧键断裂）和氢化（即碳 - 氢键形成）是铜电极催化的两种主要表面反应类型。在这项工作中，我们通过进行最先进的受限从头算分子动力学模拟，系统地研究了涉及两种重要中间体COHads和CHOads的脱氧和氢化反应，这些反应分别发生在以下各种条件下：（i）无水分子存在的Cu(100)表面上；（ii）水/Cu(100)界面处；（iii）带电的水/Cu(100)界面处，以阐明电化学界面的影响。研究发现，电化学界面可通过改变反应机制极大地促进碳 - 氧键的断裂。然而，碳 - 氢键的形成并未受到水或电荷存在的影响。此外，还分别阐明了水环境和负电极电位在脱氧过程中的促进作用。这项基础研究为电化学界面在电催化中的重要性提供了原子层面的见解，这对于理解电化学具有普遍意义。
