Electronic‐Structure‐Guided Screening of Piperazine Derivatives: Achieving Efficient CO ₂ Capture with High Cyclic Capacity and Low Energy Consumption

Abstract Piperazine (PZ) is a promising alternative to monoethanolamine (MEA) for CO ₂ capture, yet its low desorption efficiency restricts practical implementation. Here, a density functional theory (DFT)‐driven framework is developed to identify PZ derivatives with improved performance. By integrating electronic descriptors—including molecular electrostatic potential (ESP) for absorption capacity, ESP at hydrogen nuclei (ESP_H) for desorption efficiency, activation barrier (ΔG‡) and Gibbs free energy change (ΔG) for absorption rate, and interaction‐region indicator (IRI) for energy consumption—the key performance of the derivatives is predicted. Experimental validation confirms the framework's predictive accuracy, with 2,6‐dimethylpiperazine (26DMPZ) identified as an optimal candidate. It demonstrates a desorption amount of 0.72 mol mol ⁻¹ ‐amine (≈80% higher than PZ), due to more negative ESP_H values. Furthermore, it shows 31% lower energy consumption compared to MEA, attributed to unstable dicarbamate formation. Spectroscopic analyses and solvation free energy calculations reveal that the low‐solubility of this dicarbamate salt further enhances CO ₂ capture performance without requiring organic solvents. Notably, the system retains 98.4% of its initial cyclic capacity over 10 rapid absorption–desorption cycles, indicating the industrial application potential. This study establishes an electronic‐structure‐guided screening strategy for amine solvents, highlighting precipitation‐driven phase separation as a tunable mechanism to optimize CO ₂ capture performance.