fig3

Figure 3. (A) Vertical contact-separation mode, Lateral sliding mode, Single-electrode mode, and Freestanding triboelectric-layer mode^[15]. Zhao et al. (2020), John Wiley and Sons^[15]. (B) Two atoms at a distance greater than the bonding length, illustrating initial attraction without contact. (C) Atoms within the repulsive force region, showing interaction potential with a distance shorter than the bonding length but not leading to electron transition. (D) Separated electron clouds of two atoms before contact, depicting the stage prior to electron transition. (E) Overlapped electron clouds under mechanical pressure, showing lowered potential barrier and enabling electron transition^[58].