Universal Skeleton Feature of the Three-Dimensional Volcano Surface and the Thermodynamic Rule in Locating the Catalyst in Heterogeneous Catalysis

Constructing a three-dimensional volcano surface (3DVS) that has been a primary focus in the evaluation of activity for complex heterogeneous catalytic systems relies normally on heavy time-consuming first-principles calculations under specific conditions. Therefore, theoretically revealing the universal kinetic characteristics of a 3DVS will greatly facilitate the understanding of overall activity trends among different catalysts and provide guidance to the rational design of catalysts. Herein, we report a systematic theoretical elucidation on the origin of the intricate kinetic characteristics of a 3DVS in the framework of a generalized three-step consecutive reaction model, revealing that the 3DVS can be divided into six slope zones and a summit zone bound by three kinetic feature lines (KFLs) and three thermodynamic feature lines (TFLs), where KFLs are relevant with the reaction type and local configuration of the catalyst surface, while TFLs are only determined by the gas-phase thermodynamics of reactants/products (R/P). Remarkably, the position of these feature lines can be quantitatively formulated, which can be used to quickly sketch the outline of the 3DVS. More importantly, the summit of the 3DVS is found to locate in a “thermodynamic window” simply estimated with the chemical potential of R/P, and the best catalyst can be roughly located by following a basic thermodynamic rule. Moreover, starting with a given catalyst candidate, a general catalyst optimization direction for how to approach the summit of 3DVS, named as a ridge-following scheme, is quantitatively discussed. The theoretical understandings derived from this work could contribute to the efficient design of heterogeneous catalysts.