Dynamic Stability of Copper Single-Atom Catalysts under Working Conditions
Dynamic Stability of Copper Single-Atom Catalysts under Working Conditions
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DOI：
10.1021/jacs.2c07178
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发表时间：
2022-09-11
影响因子：
15
通讯作者：
Liu, Yuanyue
中科院分区：
文献类型：
--
作者：
Bai, Xiaowan;Zhao, Xunhua;Liu, Yuanyue
单原子催化剂的长期稳定性是影响其大规模商业应用的主要因素。如何评价单原子催化剂在工作条件下的动态稳定性，目前还缺乏。在此，以嵌入N掺杂石墨烯中的单个铜原子为例，使用“恒势混合溶剂化动力学模型“来评估在现实反应条件下铜单个原子与团簇之间的可逆转化。结果表明，H的吸附是Cu单原子从催化剂表面浸出的重要驱动力。电极电位越负，吸附H越强;其结果是，竞争析氢反应被抑制，并且Cu-N键被削弱，导致一些Cu原子被束缚在催化剂表面上，并且一些被溶解在水溶液中。Cu原子在两种状态下的碰撞形成了一个短暂的Cu团簇结构，作为一个真正的催化活性中心，以促进CO2还原为乙醇。当外加电位被释放或切换到正值时，羟基自由基（OH & B）在Cu团簇的氧化过程中起主导作用，然后Cu通过再沉积回到初始原子分散状态，完成铜催化剂的重构循环。我们的工作提供了一个基本的理解，在原子水平的工作条件下的动态稳定性的铜单原子催化剂，并要求重新评估目前报道的单原子催化剂考虑现实的反应条件下的稳定性。
The long-term stability of single-atom catalysts is a major factor affecting their large-scale commercial application. How to evaluate the dynamic stability of single-atom catalysts under working conditions is still lacking. Here, taking a single copper atom embedded in N-doped graphene as an example, the "constant-potential hybrid-solvation dynamic model " is used to evaluate the reversible transformation between copper single atoms and clusters under realistic reaction conditions. It is revealed that the adsorption of H is a vital driving force for the leaching of the Cu single atom from the catalyst surface. The more negative the electrode potential, the stronger the adsorption of H. As a result, the competitive hydrogen evolution reaction is inhibited, and Cu-N bonds are weakened, resulting in some Cu atoms being tethered on the catalyst surface and some being dissolved in the aqueous solution. The collision of the Cu atoms in the two states forms a transient Cu cluster structure as a true catalytic active site to promote CO2 reduction to ethanol. As the applied potential is released or switched to a positive value, hydroxyl radicals (OH & BULL;) play a dominant role in the oxidation process of the Cu cluster, and then Cu returns to the initial atomic dispersion state by redeposition, completing the reconstruction cycle of the copper catalyst. Our work provides a fundamental understanding of the dynamic stability of Cu single-atom catalysts under working conditions at the atomic level and calls for a reassessment of the stability of currently reported single-atom catalysts considering realistic reaction conditions.