Giulimondi Vera, Kaiser Selina K, Martín Antonio J, Büchele Simon, Krumeich Frank, Clark Adam H, Pérez-Ramírez Javier
Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, Zürich, 8093, Switzerland.
Paul Scherrer Institute, Villigen PSI, 5232, Switzerland.
Small. 2022 Apr;18(15):e2200224. doi: 10.1002/smll.202200224. Epub 2022 Feb 27.
The introduction of a foreign metal atom in the coordination environment of single-atom catalysts constitutes an exciting frontier of active-site engineering, generating bimetallic low-nuclearity catalysts often exhibiting unique catalytic synergies. To date, the exploration of their full scope is thwarted by (i) the lack of synthetic techniques with control over intermetallic coordination, and (ii) the challenging characterization of these materials. Herein, carbon-host functionalization is presented as a strategy to selectively generate Au-Ru dimers and isolated sites by simple incipient wetness impregnation, as corroborated by careful X-ray absorption spectroscopy analysis. The distinct catalytic fingerprints are unveiled via the hydrogen evolution reaction, employed as a probe for proton adsorption properties. Intriguingly, the virtually inactive Au atoms enhance the reaction kinetics of their Ru counterparts already when spatially isolated, by shifting the proton adsorption free energy closer to neutrality. Remarkably, the effect is magnified by a factor of 2 in dimers. These results exemplify the relevance of controlling intermetallic coordination for the rational design of bimetallic low-nuclearity catalysts.
在单原子催化剂的配位环境中引入外来金属原子是活性位点工程中一个令人兴奋的前沿领域，可生成通常表现出独特催化协同作用的双金属低核催化剂。迄今为止，对其全部范围的探索受到以下因素的阻碍：（i）缺乏能够控制金属间配位的合成技术，以及（ii）这些材料具有挑战性的表征。在此，通过仔细的X射线吸收光谱分析证实，碳载体功能化被提出作为一种通过简单的初湿浸渍选择性生成金-钌二聚体和孤立位点的策略。通过析氢反应揭示了不同的催化特征，该反应被用作质子吸附性质的探针。有趣的是，实际上无活性的金原子在空间上孤立时就已经通过将质子吸附自由能移近中性来增强其钌对应物的反应动力学。值得注意的是，在二聚体中这种效应放大了2倍。这些结果例证了控制金属间配位对于双金属低核催化剂合理设计的重要性。
