英国卡迪夫大学Hutchings, Graham J.团队报道了Au-Pd分离增强醇氧化双金属催化作用。相关研究成果于2022年1月17日发表在《自然》。
在以氧为末端氧化剂的负载型金属纳米粒子催化的氧化反应中，氧还原速率可能是一个限制因素。醇的氧化脱氢反应就是一个例子，这是一类具有现代商业应用的重要反应。负载型金纳米颗粒对乙醇脱氢生成醛具有很高的活性，但对氧还原的效果较差。相比之下，负载型钯纳米颗粒在脱氢方面的活性不如金，但在氧还原方面具有很高的效率。这种不平衡可以通过将金与钯合金化来克服，从而提高两种反应的活性；然而，合金的电化学电位介于两种金属的电化学电位之间，这意味着尽管合金中的氧还原有所改善，但脱氢活性较差。
该文中，研究表明，通过分离双金属碳载体催化剂中的金和钯组分，几乎可以将反应速率提高一倍，超过相应合金催化剂的反应速率。研究人员使用碳载单金属金和钯的物理混合物以及包含分离的金和钯区域的双金属催化剂来证明这一点。此外，用电化学方法证明，这种增强可归因于发生在孤立金和钯位置的单独氧化还原过程的耦合。这种新的催化效应——协同氧化还原增强（CORE）的发现为多组分多相催化剂的设计提供了新的途径。
附：英文原文
Title: Au-Pd Separation Enhances Bimetallic Catalysis of Alcohol Oxidation
Author: Huang, Xiaoyang, Akdim, Ouardia, Douthwaite, Mark, Wang, Kai, Zhao, Liang, Lewis, Richard J., Pattisson, Samuel, Daniel, Isaac T., Miedziak, Peter J., Shaw, Greg, Morgan, David J., Althahban, Sultan M., Davies, Thomas E., He, Qian, Wang, Fei, Fu, Jile, Bethell, Donald, McIntosh, Steven, Kiely, Christopher J., Hutchings, Graham J.
Issue&Volume: 2022-01-17
Abstract: In oxidation reactions catalysed by supported metal nanoparticles with oxygen as the terminal oxidant, the rate of the oxygen reduction can be a limiting factor. This is exemplified by the oxidative dehydrogenation of alcohols, an important class of reactions with modern commercial applications1–3. Supported gold nanoparticles are highly active for the dehydrogenation of the alcohol to an aldehyde4 but are less effective for oxygen reduction5,6. In contrast, supported palladium nanoparticles are less active than gold for dehydrogenation but offer high efficacy for oxygen reduction5,6. This imbalance can be overcome by alloying gold with palladium which gives enhanced activity to both reactions7,8; however, the electrochemical potential of the alloy is a compromise between that of the two metals meaning that although the oxygen reduction is improved in the alloy, the dehydrogenation activity is poorer. Here we show that by separating the gold and palladium components in bimetallic carbon-supported catalysts we can almost double the reaction rate beyond that achieved with a corresponding alloy catalyst. We demonstrate this using physical mixtures of carbon-supported monometallic gold and palladium and a bimetallic catalyst comprising separated gold and palladium regions. Furthermore, we demonstrate electrochemically that this enhancement is attributable to the coupling of separate redox processes occurring at isolated gold and palladium sites. The discovery of this novel catalytic effect, a cooperative redox enhancement (CORE), offers a new approach to the design of multi-component heterogeneous catalysts.
DOI: 10.1038/s41586-022-04397-7
Source: https://www.nature.com/articles/s41586-022-04397-7