Reduction of CO₂ to useful chemicals using supported few atom copper clusters has been an active area of research. The first step in this process is chemisorption and reduction of CO₂ to CO${}_2^{\delta -}$. Previous studies have shown that the ease of chemisorption depends on the cluster geometry and charge. In an effort to elucidate the role of cluster-support interactions and thereby cluster geometry, charge on cluster on CO₂ chemisorption, in this work, using density functional theory based calculations, we have studied the physisorption and chemisorbtion of CO₂ on Cu tetramers supported on pristine and O-terminated Ti₂C MXene. Our calculations show that for CO₂ to exhibit exothermic adsorption, the cluster should (a) wet the support thereby exposing all the Cu atoms to the approaching CO₂ molecule, (b) be preferably positively charged with Cu atoms present in more than one oxidation state and (c) be fluxional on the support. Our nudged elastic band based calculations show that the transition from physisorbed to chemisorbed CO₂ is an activated process. Amongst the systems considered in this study, the activation barrier is usually low except on the tetrahedral cluster on the oxygen terminated Ti₂C support.

使用支持的少量原子铜簇将CO ₂还原为有用的化学物质一直是研究的活跃领域。此过程的第一步是化学吸附并将CO ₂还原为CO${}_{\mathrm{2个}}^{\delta -}$。先前的研究表明，化学吸附的难易程度取决于团簇的几何形状和电荷。为了阐明簇-载体相互作用的作用，从而阐明簇的几何形状，簇对CO ₂化学吸附的电荷，在这项工作中，我们使用基于密度泛函理论的计算方法，研究了负载的Cu四聚体对CO ₂的物理吸附和化学吸附。在原始的和O端接的Ti ₂ C MXene上。我们的计算表明，要使CO ₂表现出放热吸附，团簇应（a）润湿载体，从而将所有Cu原子暴露于接近的CO _2中。在分子中，（b）优选以多于一种氧化态存在的Cu原子带正电荷，并且（c）在载体上是通量的。我们基于微带的微带计算表明，从物理吸附到化学吸附的CO ₂的转变是一个激活的过程。在这项研究中考虑的系统中，除了在氧封端的Ti ₂ C载体上的四面体簇上，活化势垒通常很低。