The direct synthesis of hydrogen peroxide over Au and Pd nanoparticles: A DFT study
The direct synthesis of hydrogen peroxide over Au and Pd nanoparticles: A DFT study
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DOI：
10.1016/j.cattod.2020.09.001
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发表时间：
2021-09-22
期刊：
影响因子：
5.3
通讯作者：
Willock, David J.
中科院分区：
文献类型：
--
作者：
Agarwal, Nishtha;Thomas, Liam;Willock, David J.
由Au、Pd及其合金组成的催化剂已被证明是活性氧化催化剂。这些材料可以使用分子氧或过氧化氢作为氧化剂，CO和活化的有机分子使用O2（g），而更具挑战性的情况下，如甲烷部分氧化，依赖于H2O2。虽然H2O2是一种绿色氧化剂，但引入分子氧大大降低了总成本，因此有动机寻找新的方法来减少对H2O2的依赖。在这项研究中，我们使用DFT计算来讨论从H2（g）和O2（g）直接合成H2O2，并使用这种理解来识别来自分子氧的重要表面物种。我们涵盖了吸附的氧气，氢气和水的模型Au和Pd纳米团簇和氧化的金属，因为还原形成的任何氧化物将消耗H2。然后，我们转向生产的表面过氧化氢物种，在H2O2合成的第一步。这可以通过用H2（ads）氢化O2（ads）或通过溶剂水质子化O2（ads）来进行。这两种途径被认为是积极合理的，但后者很可能是有利的实验条件下。
Catalysts consisting of Au, Pd and their alloys have been shown to be active oxidation catalysts. These materials can use dioxygen or hydrogen peroxide as the oxidant with CO and activated organic molecules using O2(g) while more challenging cases, such as methane to partial oxygenates, relying on H2O2. Although H2O2 is a green oxidant, the incorporation of dioxygen greatly reduces overall cost and so there is an incentive to find new ways to reduce the reliance on H2O2. In this study we use DFT calculations to discuss the direct synthesis of H2O2 from H2(g) and O2(g) and use this understanding to identify the important surface species derived from dioxygen. We cover the adsorption of oxygen, hydrogen and water to model Au and Pd nanoclusters and the oxidation of the metals, since reduction of any oxides formed will consume H2. We then turn to the production of a surface hydroperoxy species; the first step in the synthesis of H2O2. This can occur via hydrogenation of O2(ads) with H2(ads) or via protonation of O2(ads) by solvent water. Both routes are found to be energetically reasonable, but the latter is likely to be favoured under experimental conditions.