Geometrically isolated metal atoms in alloy catalysts can target efficient and selective catalysis. However, the geometric and electronic disturbance between the active atom and its neighbouring atoms, that is, diverse microenvironments, makes the active site ambiguous. Herein, we demonstrate a methodology to describe the microenvironment and determine the effectiveness of active sites in single-site alloys. A simple descriptor, degree-of-isolation, is proposed, considering both electronic regulation and geometric modulation within a PtM ensemble (M = transition metal). The catalytic performance of PtM single-site alloy is examined thoroughly using this descriptor for an industrially important reaction, propane dehydrogenation. The volcano-shaped isolation–selectivity plot reveals a Sabatier-type principle for designing selective single-site alloys. Specifically, for a single-site alloy with a high degree-of-isolation, alternation of the active centre has a great impact on tuning selectivity, validated by the outstanding consistency between experimental propylene selectivity and the computational descriptor.

合金催化剂中几何隔离的金属原子可以针对高效和选择性催化。然而，活性原子与其相邻原子之间的几何和电子干扰，即多样化的微环境，使得活性位点不明确。在此，我们展示了一种描述微环境并确定单点合金中活性位点有效性的方法。考虑到 PtM 系综（M = 过渡金属）内的电子调节和几何调制，提出了一个简单的描述符，即隔离度。使用此描述符对工业上重要的丙烷脱氢反应彻底检查了 PtM 单位点合金的催化性能。火山形隔离-选择性图揭示了用于设计选择性单位点合金的 Sabatier 型原理。具体而言，对于具有高隔离度的单中心合金，活性中心的交替对调谐选择性有很大影响，实验丙烯选择性与计算描述符之间的出色一致性验证了这一点。