Role of Defects in Graphene-Passivated Ti₃C₂ MXene for Energy Conversion and Storage Applications: A First-Principles Study

MXene-related materials have a large surface area, strong metallic conductivity, and rapid redox activity that make them desirable electrodes for energy conversion and storage applications. However, surface aggregation, oxidation, and vacancies have hindered their applications. In this study, we computationally investigated the structural, electronic, mechanical, catalytical, and charge-storage properties of 2D Ti₃C₂ MXene passivated with graphene by means of first-principles calculations within the density functional theory (DFT) frames. Graphene passivation enhances not only the thermodynamic and mechanical stability of MXene but also the electrical conductivity to a large extent. The intrinsic defects in MXene possess high catalytic activity for the hydrogen evolution reaction, whereas N-doped graphene-passivated MXene outperforms the pristine counterpart for the charge storage. Our DFT calculations reveal that M/G with defects is a suitable material for electrochemical energy conversion and storage applications.