Effect of structural defects on the physiochemical properties of supportive single-layer graphene in a sliding electrical contact interface under ambient conditions

We investigated the physiochemical properties of single-layer graphene (SLG) with controlled structural defects that were used in sliding electrical contact. Conductive atomic force microscopy (cAFM) probes applied with electric biases were used to rub the SLG surface under ambient conditions. Structural and chemical properties of rubbed SLG were investigated using Raman spectroscopy, photothermal infrared atomic force microscopy (AFM), and X-ray photoelectron spectroscopy. The work function (WF) and conductivity were determined using Kelvin probe force microscopy and cAFM. Adhesive properties were examined using AFM in the force-volume mode. Biases applied to the cAFM probe resulted in the tunneling triboelectric effect (TTE), which modulated the WF of SLG. The formation of water menisci around the cAFM probe-SLG contact will be electrolyzed, leading to the surface oxidation of SLG, which also impacts the WF of SLG. Compared with pristine SLG with minimum defects, more-defective SLG enhanced the TTE and surface functionalization during the rubbing process, substantially affecting the morphological, electronic, chemical, and adhesive properties of rubbed defective SLG. Our results demonstrated that the physiochemical properties of SLG in a sliding contact are considerably affected by the presence of structural defects in SLG, which should be considered when SLG is used for electrode applications.