Cu(111)、Cu(100)和Cu(211)表面水煤气变换反应机理研究,ACS Omega

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Cu(111)、Cu(100)和Cu(211)表面水煤气变换反应机理研究
ACS Omega ( IF 3.7 ) Pub Date : 2022-01-14 , DOI: 10.1021/acsomega.1c05991
Zhiyuan Li ₁ , Na Li ₁ , Nan Wang ₁ , Bing Zhou ₁ , Pan Yin ₂ , Boyu Song ₂ , Jun Yu ₂ , Yusen Yang ₂

Affiliation

铜基催化剂由于其低成本和高催化活性而常用于低温水煤气变换（WGS）反应。不同Cu表面对WGS反应催化活性和机理的影响仍不清楚。在这项工作中，使用密度泛函理论 (DFT) 研究了不同表面结构对 WGS 机制的影响。考虑了 Cu 的三个表面末端（Cu(100)、Cu(111) 和 Cu(211)），活性 Cu 位点的配位数（CN）在 7 到 9 之间。最稳定的表面是Cu(211)。然后，计算 d 波段中心值，其按以下顺序递减：Cu(211) > Cu(100) > Cu(111)。这表明 d 波段中心值随着配位数的增加而减小。₂ O 吸附物，符合 d 带中心理论。此外，进一步计算了三种不同Cu表面上WGS反应的机理表明羧基路径是最有利的机理，而决定速率的步骤是H ₂ O解离。Cu(211) 表现出优异的 WGS 催化性能，优于 Cu(100) 和 Cu(111) 表面。这项工作为合理设计用于 WGS 反应的高活性铜基催化剂提供了理论见解。

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Mechanism Investigations on Water Gas Shift Reaction over Cu(111), Cu(100), and Cu(211) Surfaces

Cu-based catalysts are commonly applied in low-temperature water gas shift (WGS) reactions, owing to their low cost and high catalytic activity. The influence of different Cu surfaces on catalytic activity and mechanism over the WGS reaction remains unclear. In this work, the effect of different structures of surfaces on the WGS mechanism is studied using density functional theory (DFT). Three surface terminations (Cu(100), Cu(111), and Cu(211)) of Cu are considered, and the coordination number (CN) of the active Cu site is in the range from 7 to 9. The most stable surface is Cu(211). Then, d-band center values are calculated, which decrease in the following sequence: Cu(211) > Cu(100) > Cu(111). This shows that d-band center values decrease with increasing coordination number. The increase in the centers of the d-band leads to an increase in the adsorption strength of CO and H₂O adsorbates, which is in line with the theory of the d-band center. In addition, the further calculated mechanism for WGS reaction over three different Cu surfaces illustrates that the carboxyl path is the most favorable mechanism, and the rate-determining step is H₂O dissociation. Cu(211) shows excellent WGS catalytic performance, better than the Cu(100) and Cu(111) surfaces. This work provides theoretical insights into the rational design of highly active Cu-based catalysts toward WGS reaction.

更新日期：2022-02-01

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