High-efficiency and low-cost Pd-based catalyst is of vital importance toward CO oxidation to dimethyl oxalate (DMO). Here, we design Pd monolayer, Pd stripe and Pd single atom embedded on Ag(111) surfaces, i.e. Pd_ML/Ag(111), Pd₄Ag₈/Ag(111) and Pd₁-Ag(111), to investigate the effect of different content of Pd atoms in Ag substrate toward DMO formation. The density functional theory (DFT) calculation illustrates that the optimal pathway to produce DMO is two COOCH₃ intermediates coupling route on three catalyst surfaces, which is the same to the Pd(111) surface, showing that it has no influence on the favorable route of DMO formation. Additionally, the DFT combined with micro-kinetic analysis indicates that Pd₁-Ag(111) exhibits the highest activity for DMO generation, Pd_ML/Ag(111) is superior to Pd(111), while Pd₄Ag₈/Ag(111) is inferior to Pd(111). Among them, the high activity on the Pd₁-Ag(111) is attributed to strain effect and ligand effect both reducing activation barrier of the rate-controlling step. Moreover, Pd₁-Ag(111) shows high selectivity for DMO, whereas it is opposite on the Pd_ML/Ag(111). Therefore, it is proposed that Pd₁-Ag single atom surface alloy can be the promising candidate not only improving the noble Pd’s catalytic performance for DMO formation but also reducing its usage.

高效，低成本的Pd基催化剂对于将CO氧化为草酸二甲酯（DMO）至关重要。在这里，我们设计嵌入在Ag（111）表面上的Pd单层，Pd条带和Pd单原子，即Pd _ML / Ag（111），Pd ₄ Ag ₈ / Ag（111）和Pd ₁ -Ag（111），以进行研究Ag基质中不同含量的Pd原子对DMO形成的影响。密度泛函理论（DFT）计算表明，生产DMO的最佳途径是在三个催化剂表面上的两个COOCH ₃中间体偶联途径，与Pd（111）表面相同，表明它对有利途径没有影响。 DMO的形成。此外，DFT结合微动力学分析表明，Pd_1- Ag（111）表现出最高的DMO生成活性，Pd _ML / Ag（111）优于Pd（111），而Pd ₄ Ag ₈ / Ag（111）不如Pd（111）。其中，对Pd ₁ -Ag（111）的高活性归因于应变效应和配体效应，两者均降低了速率控制步骤的活化势垒。此外，Pd ₁ -Ag（111）对DMO具有高选择性，而在Pd _ML / Ag（111）上却相反。因此，提出Pd ₁ -Ag单原子表面合金不仅可以提高贵金属Pd对DMO形成的催化性能，而且可以减少其用量，可以成为有前途的候选物。