Resolving the Oxygen Species on Ozone Activated AgAu Alloy Catalysts for Oxidative Methanol Coupling
Resolving the Oxygen Species on Ozone Activated AgAu Alloy Catalysts for Oxidative Methanol Coupling
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DOI：
10.1021/acs.jpcc.2c03769
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发表时间：
2022-12
期刊：
影响因子：
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通讯作者：
Tiancheng Pu;J. Jehng;Adhi Setiawan;Bar Mosevitzky Lis;M. E. Ford;S. Rangarajan;I. Wachs
中科院分区：
文献类型：
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作者：
Tiancheng Pu;J. Jehng;Adhi Setiawan;Bar Mosevitzky Lis;M. E. Ford;S. Rangarajan;I. Wachs
双金属合金催化剂经常表现出上级其单金属催化剂的独特性能，但需要仔细研究其表面化学以了解其结构-活性关系。纳米多孔Ag0.03Au0.97合金催化剂经O3活化后，对甲醇氧化偶联制甲酸甲酯具有高活性和选择性. HS-LEIS表明，O3处理导致Ag（>30%）富集在最外表面层上，而氧处理另外导致更大部分的Cu杂质在表面上的偏析。在395、577、867和904 cm-1处的一系列特征拉曼谱带仅在O3活化的AgAu催化剂上的甲醇氧化偶联反应中形成。这些谱带对应于O-Au（111）和AgAu合金上的Ag 3-O*（395 cm-1）、M-O*（577 cm-1）、CH 3OH *（867 cm-1）和HOOH*（904 cm-1），如DFT计算所揭示的。的cyclicin situRaman和反应性的研究表明，检测到的氧物种可能与预处理后的催化剂的“记忆效应”。目前的研究强调了应用表面特异性技术的合金催化剂的最外表面层的组成的调查，以及集成ofin situspectroscopies和计算研究的重要性，了解在分子水平上的反应条件下的表面结构。
Bimetallic alloy catalysts frequently demonstrate distinct performances that are superior to their monometallic counterparts, yet their surface chemistry needs to be carefully studied to understand their structure–activity relationships. The nanoporous Ag0.03Au0.97alloy catalyst becomes highly active and selective for oxidative methanol coupling to methyl formate after O3activation. HS-LEIS reveals the O3treatment results in enrichment of Ag (>30%) on the outermost surface layer, while oxygen treatment additionally leads to segregation of a larger portion of Cu impurity on the surface. A series of characteristic Raman bands at 395, 577, 867, and 904 cm–1only form under oxidative methanol coupling reaction on O3-activated AgAu catalyst. These bands correspond to Ag3–O* (395 cm–1), M–O* on O–Au(111) and AgAu alloy (577 cm–1), CH3OH* (867 cm–1), and HOOH* (904 cm–1), as revealed by DFT calculations. The cyclicin situRaman and reactivity studies indicate the detected oxygen species could be related to a “memory effect” of the catalyst upon pretreatment. The current study highlights the importance of applying surface-specific techniques for investigation of compositions of outermost surface layers of alloy catalysts, as well as integration ofin situspectroscopies and computational investigations for understanding surface structures at the molecular level under reaction conditions.