High-Throughput Screening of Atomic Defects in MXenes for CO₂ Capture, Activation, and Dissociation

The capture, activation, and dissociation of carbon dioxide (CO₂) is of fundamental interest to overcome the ramifications of the greenhouse effect. In this regard, high-throughput screening of two-dimensional MXenes has been examined using well-resolved first-principles simulations through DFT-D3 dispersion correction. We systematically investigated different types of structural defects to understand their influence on the performance of M₂X-type MXenes. Defect calculations demonstrate that the formation of M₂C(V_MC) and M₂N(V_MN) vacancies require higher energy, while M₂C(V_C) and M₂N(V_N) vacancies are favorable to form during the synthesis of M₂X-type MXenes. The M₂X-type MXenes from group III to VII series show remarkable behavior for active capturing of CO₂, especially group IV (Ti₂X and Zr₂X) MXenes exhibit unprecedentedly high adsorption energies and charge transfer (>2e) from M₂X to CO₂. The potential CO₂ capture, activation, and dissociation abilities of MXenes are emanated from Dewar interactions involving hybridization between π orbitals of CO₂ and metal d-orbitals. Our high-throughput screening demonstrates chemisorption of CO₂ on pure and defective MXenes, followed by dissociation into CO and O species.