Due to the unstable nature of isolated transition metals under real reaction condition, a systematic understanding on how much influence the isolated structure of the active site and the cofed chemicals have on fine tuning the selectivity toward specific reaction pathways is still lacking. Here, we show a combination of kinetic, thermodynamic, and in situ spectroscopy measurements to probe the rWGS and methanation of carbon dioxide on a CeO₂-dispersed isolated Ru catalyst (Ru-SnO_x/CeO₂, structure confirmed by HAADF-STEM) derived from the [Ru@Sn₉]^6– Zintl cluster decoration. Kinetic measurements, in combination with isotopie-labeling reactions, prove that rWGS and methanation occur through the kinetically relevant C–O bond rupture of surface carboxyl (HOCO*) and surface formate (HCOO*) respectively. A site-selective reaction model has been established on the basis of the response of rWGS and methanation to water pressure. Probably, the rWGS was carried out at the interface between the transition-metal nanoparticles and the support and could be influenced greatly by water, while the methanation was carried out at a site far away from the interface and has a weak dependence on water. This system can be easily extended to some other hydrogenation reactions, thus attracting attention to building isolated structures with Zintl clusters.

中文翻译：

---

[Ru @ Sn ₉ ] ^6– Zintl簇衍生的高度分散的Ru-SnO _x位点的位点选择性CO ₂减少

由于分离的过渡金属在真实反应条件下的不稳定性质，仍然缺乏对活性位点和化合物化学结构的分离结构对微调对特定反应途径的选择性有多大影响的系统理解。在这里，我们展示了动力学，热力学和原位光谱测量的组合，以在分散有CeO _2的分离式Ru催化剂（Ru-SnO _x / CeO ₂，由HAADF-STEM确认的结构）上探测rWGS和二氧化碳的甲烷化源自[Ru @ Sn ₉ ] ^6–Zintl群集装饰。动力学测量与同位素标记反应相结合，证明rWGS和甲烷化分别通过表面羧基（HOCO *）和表面甲酸（HCOO *）的动力学相关C-O键断裂而发生。基于rWGS和甲烷化对水压的响应，已经建立了位点选择性反应模型。rWGS可能是在过渡金属纳米粒子与载体之间的界面上进行的，并且可能受到水的影响很大，而甲烷化作用则是在远离界面且对水的依赖性较弱的位置进行的。该系统可以很容易地扩展到其他一些氢化反应，因此引起了人们对用Zintl簇构建孤立结构的关注。