Modeling single-atom reactivity Noble metals often perform best for demanding reactions such as oxygen reduction, an effect often explained by the position of their d-band. One way to minimize the cost of noble metals is to disperse them as single atoms. To model the reactivity of supported single atoms, Hulva et al. evaporated different transition metals such as nickel, silver, and iridium on an Fe3O4(001) support. Single atoms adsorbed in the same twofold site between underlying rows of surface iron atoms. In studies of CO adsorption as a proxy for reactivity, the d-band was strongly affected by the charge transfer to the support and CO-induced structural changes. These effects can weaken the adsorption energy compared with the expected values based on electronic structure alone. Science, this issue p. 375 Single metal atoms supported on iron oxides have chemical properties defined by their local coordination environment. Understanding how the local environment of a “single-atom” catalyst affects stability and reactivity remains a challenge. We present an in-depth study of copper1, silver1, gold1, nickel1, palladium1, platinum1, rhodium1, and iridium1 species on Fe3O4(001), a model support in which all metals occupy the same twofold-coordinated adsorption site upon deposition at room temperature. Surface science techniques revealed that CO adsorption strength at single metal sites differs from the respective metal surfaces and supported clusters. Charge transfer into the support modifies the d-states of the metal atom and the strength of the metal–CO bond. These effects could strengthen the bond (as for Ag1–CO) or weaken it (as for Ni1–CO), but CO-induced structural distortions reduce adsorption energies from those expected on the basis of electronic structure alone. The extent of the relaxations depends on the local geometry and could be predicted by analogy to coordination chemistry.

中文翻译：

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解开模型单原子催化剂上的 CO 吸附

模拟单原子反应性贵金属通常在氧还原等要求苛刻的反应中表现最佳，这种效应通常由其 d 带的位置来解释。将贵金属成本降至最低的一种方法是将它们分散为单个原子。为了模拟支持的单原子的反应性，Hulva 等人。在 Fe3O4(001) 载体上蒸发了不同的过渡金属，如镍、银和铱。单个原子吸附在底层表面铁原子行之间的相同双重位置。在 CO 吸附作为反应性代理的研究中，d 带受到电荷转移到载体和 CO 引起的结构变化的强烈影响。与仅基于电子结构的预期值相比，这些影响可以削弱吸附能。科学，这个问题 p。375 负载在氧化铁上的单个金属原子具有由其局部配位环境定义的化学性质。了解“单原子”催化剂的局部环境如何影响稳定性和反应性仍然是一个挑战。我们对 Fe3O4(001) 上的铜 1、银 1、金 1、镍 1、钯 1、铂 1、铑 1 和铱 1 物种进行了深入研究，Fe3O4(001) 是一种模型载体，其中所有金属在室内沉积时占据相同的双重配位吸附位点温度。表面科学技术表明，单个金属位点的 CO 吸附强度不同于各自的金属表面和负载簇。电荷转移到载体上会改变金属原子的 d 态和金属-CO 键的强度。这些影响可以加强键（如 Ag1-CO）或削弱它（如 Ni1-CO），但是 CO 引起的结构扭曲降低了仅基于电子结构所预期的吸附能。弛豫的程度取决于局部几何形状，可以通过类比配位化学来预测。