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, strongmetallicconductivity, and rapid redox activity that make them desirable electrodesfor energy conversion and storage applications. However, surface aggregation,oxidation, and vacancies have hindered their applications. In thisstudy, we computationally investigated the structural, electronic,mechanical, catalytical, and charge-storage properties of 2D Ti3C2 MXene passivated with graphene by means of first-principlescalculations within the density functional theory (DFT) frames. Graphenepassivation enhances not only the thermodynamic and mechanical stabilityof MXene but also the electrical conductivity to a large extent. Theintrinsic defects in MXene possess high catalytic activity for thehydrogen evolution reaction, whereas N-doped graphene-passivated MXeneoutperforms the pristine counterpart for the charge storage. Our DFTcalculations reveal that M/G with defects is a suitable material forelectrochemical energy conversion and storage applications.