Figure 4: The effect of tip material on the local chemical reaction
From: Direct mechanochemical cleavage of functional groups from graphene
(a) Relative friction drop on OG as a function of contact stress for a diamond (green), silicon (black) and silicon nitride (orange) tip. For reference, the data for Si is the same as for Fig. 3. The error bars were calculated as the s.d. of lateral force divided by the average lateral force for each data point. (b) Derivative of the friction decrease for all three tips, showing that the kinetics of oxygen group removal is the same for SiN and Si tips, while the diamond tip removes the oxygen groups with ~4 × lower contact stress. The data was smoothed using the Savitzky–Golay smoothing algorithm to clearly show the trends.
