Pd-based catalysts in which the Pd is alloyed with a transition metal (TM) are often considered for the direct synthesis of H₂O₂. In particular, PdAu and PdHg alloys are known for their good catalytic activities. However, finding suitable catalysts with designed compositions is not easy and the fundamental understanding of the mechanisms behind their enhanced activities is often lacking. In the current study, descriptor sets for direct H₂O₂ synthesis on Pd, PdAu, and PdHg surfaces were proposed based on density functional theory. By considering the surface electronic effects caused by the alloy surface composition, descriptor sets consisting of the adsorption energy for reaction intermediates such as O₂, O, and OOH and activation energy barriers were derived from elementary reaction steps. The geometric factors of the adsorbed species were also considered, but found to be less important. The adsorption energies of O₂ and O were calculated and compared to determine that surface-adsorbed is the intermediate species required to form the desired product. The selectivity was assessed by comparing the adsorption energies of O and OOH. Considering the main thermodynamic and kinetic characteristics, the results showed that the PdHg alloy with a surface composition having the atomic ratio 2 : 1 gives the best selectivity. The results of the descriptor analysis indicated that alloying Pd with less active metals, such as Hg and Au, is a key strategy for designing catalysts with better catalytic activity and selectivity.

中文翻译：

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密度泛函理论分析的描述符研究，使用钯金和钯汞合金催化剂直接合成过氧化氢†

通常将其中Pd与过渡金属（TM）合金化的Pd基催化剂用于H ₂ O ₂的直接合成。特别是，PdAu和PdHg合金以其良好的催化活性而闻名。但是，要找到具有设计组成的合适催化剂并不容易，而且往往缺乏对其增强活性背后的机理的基本了解。在当前的研究中，基于密度泛函理论，提出了在Pd，PdAu和PdHg表面直接合成H ₂ O _2的描述符集。通过考虑由合金表面组成引起的表面电子效应，描述符集由反应中间体（如O _2）的吸附能组成，O和OOH以及活化能垒均来自基本反应步骤。还考虑了吸附物质的几何因素，但发现次要因素并不重要。计算并比较O ₂和O的吸附能以确定表面吸附的是形成所需产品所需的中间物种。通过比较O和OOH的吸附能来评估选择性。考虑到主要的热力学和动力学特性，结果表明，具有原子比为2：1的表面组成的PdHg合金具有最佳的选择性。描述符分析的结果表明，将Pd与活性较低的金属（例如Hg和Au）合金化是设计具有更好催化活性和选择性的催化剂的关键策略。