Berger Fabian, Schumann Julia, Réocreux Romain, Stamatakis Michail, Michaelides Angelos
Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, U.K.
Thomas Young Centre and Department of Chemical Engineering, University College London, WC1E 7JE London, U.K.
J Am Chem Soc. 2024 Oct 2;146(41):28119-30. doi: 10.1021/jacs.4c07621.
Bringing molecules together on a catalytic surface is a prerequisite for bimolecular and recombination reactions. However, in the absence of attractive interactions between reactants, such as hydrogen bonds, this poses a challenge. In contrast, based on density functional theory, we show that coadsorption at active sites of single-atom alloys (SAAs) is favored and that coadsorption is a general phenomenon observed for catalytically relevant adsorbates on a broad range of SAAs under temperature and pressure conditions commonly employed for catalysis. Dopants located in both terrace sites and in step edge defects exhibit a preference for coadsorption, displaying similar periodic trends. Using kinetic Monte Carlo simulations, we compare the reactivity of a model reaction on both a pure metal and an SAA and show that the preference for coadsorption significantly alters the overall reaction energy profile, even when the barriers for the rate-determining elementary step are identical. In our models, the coadsorption preference enhances the catalytic activity of the SAA surface by several orders of magnitude compared to the pure metal. We also report infrared (IR) spectroscopic signatures of coadsorption, which facilitate experimental detection. Analysis reveals that in these systems repulsive lateral interactions between nearby molecules are more than compensated for by the enhanced binding at dopant sites. Among the broad range of systems considered, SAAs containing early transition metals (TMs) exhibit the strongest coadsorption preference, which can be rationalized by assuming the existence of an optimal number of electrons involved in binding. The strong coadsorption preference, together with facile product desorption from early TMs, renders these systems attractive candidates for catalysis. Moreover, these SAAs could open new routes for reduction reactions because coadsorption with hydrogen is favored.
将分子聚集在催化表面上是双分子反应和重组反应的先决条件。然而，在反应物之间不存在诸如氢键等吸引相互作用的情况下，这带来了挑战。相比之下，基于密度泛函理论，我们表明单原子合金（SAA）活性位点上的共吸附是有利的，并且共吸附是在催化常用的温度和压力条件下，在广泛的SAA上观察到的催化相关吸附质的普遍现象。位于平台位点和台阶边缘缺陷处的掺杂剂都表现出对共吸附的偏好，呈现出相似的周期性趋势。使用动力学蒙特卡罗模拟，我们比较了模型反应在纯金属和SAA上的反应活性，结果表明，即使速率决定基元步骤的势垒相同，共吸附偏好也会显著改变整体反应能量分布。在我们的模型中，与纯金属相比，共吸附偏好使SAA表面的催化活性提高了几个数量级。我们还报告了共吸附的红外（IR）光谱特征，这有助于实验检测。分析表明，在这些体系中，附近分子之间的排斥性横向相互作用被掺杂剂位点增强的结合作用所补偿。在所考虑的广泛体系中，含有早期过渡金属（TM）的SAA表现出最强的共吸附偏好，这可以通过假设存在最佳数量的参与结合的电子来解释。强烈的共吸附偏好，加上早期过渡金属上产物的容易脱附，使这些体系成为有吸引力的催化候选物。此外，这些SAA可以为还原反应开辟新途径，因为它们有利于与氢共吸附。
