First-Principles Study on the Activation Mechanism during CO₂ Hydrogenation Utilizing the ZnZrO Catalytic System

Traditional computational studies often oversimplified catalyst structures and reaction steps, which are crucial to determining the correct reaction mechanisms. In the context of CO₂ reduction processes, the chemical inertness of CO₂, arising from its linear and stable molecular structure, complicates its adsorption during activation, a factor often overlooked due to the limitations of static density functional theory calculations. To address these limitations, ab initio molecular dynamics with umbrella sampling is used to accurately calculate the free energy barriers associated with CO₂ adsorption and subsequent hydrogenation in two catalytic models: ZnO(101̅0) and a more realistic model consisting of a single layer of ZnO supported on m-ZrO₂ (001) (Zn–O/M(001)). Through a rigorous analysis of the two possible reaction mechanisms, Langmuir–Hinshelwood and Eley–Rideal, we demonstrate that the Eley–Rideal mechanism is favored for both catalysts. From the perspective of CO₂ activation alone, the effective barrier on ZnO(101̅0) is lower than that on Zn–O/M(001). Our results provide new insights into the activation of CO₂ and offer valuable guidance for the rational design of optimized catalysts aimed at improving the CO₂ reduction processes. © 2025 American Chemical Society.