Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center, College of Chemistry, Nankai University, Tianjin 300071, China.
Phys Chem Chem Phys. 2020 Jan 21;22(3):1181-1186. doi: 10.1039/c9cp05624f. Epub 2019 Dec 18.
The instinctive chemical inertia of CO impedes its electrochemical reduction by high energy input. Single atom catalysts (SACs) on supports are considered as a class of excellent electrocatalysts with high activity, selectivity and atomic efficiency for CO electrochemical reduction. Supports for single atoms are believed to greatly impact the electrocatalytic activity of SACs. However, further research on the relationship between the structure of supports for SACs and CO electroreduction is still needed. Herein, density functional theory (DFT) calculations are performed to investigate the role of supports in tuning the CO electrocatalytic activity of SACs. Graphynes with different pore sizes (graphyne, graphdiyne, graphyne-3 and graphyne-4) are taken into account to unveil the effect of their skeleton structure on the anchored Cu single atoms. We found that support skeletons could greatly impact the coordination configuration of metal atoms and the steric repulsion of support skeletons to intermediates. These two factors jointly result in different electrocatalytic performances of SACs. The comparative analysis proves that the graphynes with large pores are appropriate supports for Cu adatoms for CO electroreduction due to the low-coordinated Cu atoms and weak-steric-repulsion carbon skeleton. Such SACs exhibit much enhanced activity and selectivity as compared with the Cu(111) surface and monoatomic Cu on nitrogen-doped graphene. This work provides a new insight into the rational design of supports for SACs.
CO 的本能化学惰性阻碍了其通过高能量输入进行电化学还原。负载型单原子催化剂 (SACs) 被认为是一类具有高活性、高选择性和高原子效率的优异电催化剂，可用于 CO 的电化学还原。支撑物被认为会极大地影响 SACs 的电催化活性。然而，仍然需要进一步研究 SACs 的支撑物结构与 CO 电还原之间的关系。在此，通过密度泛函理论 (DFT) 计算来研究支撑物在调节 SACs 的 CO 电催化活性方面的作用。考虑了具有不同孔径的石墨炔（石墨炔、石墨二炔、石墨炔-3 和石墨炔-4），以揭示其骨架结构对锚定的 Cu 单原子的影响。我们发现，支撑物骨架可以极大地影响金属原子的配位构型和支撑物骨架对中间体的空间排斥。这两个因素共同导致 SACs 的电催化性能不同。对比分析证明，由于低配位的 Cu 原子和弱空间排斥的碳骨架，具有大孔的石墨炔是 Cu 原子吸附用于 CO 电还原的合适支撑物。与 Cu(111) 表面和氮掺杂石墨烯上的单原子 Cu 相比，此类 SACs 表现出更高的活性和选择性。这项工作为 SACs 的支撑物的合理设计提供了新的见解。
