To reveal the fracture mechanism of

To reveal the fracture mechanism of MrO-AD sheet, molecular dynamics (MD) simulations were performed using the large-scale atomic/molecular massively parallel simulator package (LAMMPS).1 In our MD simulations, the epoxy and hydroxyl functional groups are considered in the rGO sheet, and the ratio is n-O-:nOH:nC = 0.03:0.03:1.0, which is close to the experimental sample. The width of single rGO and MXene is 2.74 nm, while the length for rGO and MXene is ~22.30 and ~3.51 nm, respectively. The hybrid sheet is constructed by depositing rGO flakes in a brick-wall manner with an initial interlayer distance of 0.55 nm, while an MXene stacking with three sheets and four AD molecules is intercalated into the rGO platelets as shown in Supplementary Fig. 25. The force field for the rGO sheet and AD molecule is all-atom optimized potentials for liquid simulation (AA-OPLS). The particle-particle-particle mesh (PPPM)2 method was used to include the long-range Columbia interaction,the 12-6 Lennard-Jones potential was used to describe the non-bonded van der Waals interaction. The MXene layer is viewed as a rigid layer to explore the sliding behavior under external stress. The periodic boundary conditions along three directions were used in the MD simulations to avoid the size effect of the simulated cell. The initial-prepared systems were relaxed in the NPT ensemble with a temperature of 300 K and a pressure of 1 bar for 500 ps, which are controlled by the Berendsen thermostat and barostat.3 The time step was 0.5 fs for the MD simulation. After the system was fully relaxed, the composite sheet were stretched in the X direction with an engineering strain rate of1 × 107 s−1 while the pressure along Y and Z direction was kept at ~1 bar. During the stretching process, the corresponding stress, strain, and atomic structure were recorded to obtain the mechanical and structural response of MrGO-AD sheet.