Figure 3.

Characterization of paper-based inkjet-printed graphene. (a) FESEM images of bare glossy paper surface without printed graphene ink (i–iii) and glossy paper surface with printed graphene ink (iv–vi) in 2 μm scale, 20 K magnification; 1 μm scale, 50 K magnification; 500 nm scale, 100 K magnification, respectively. (b) Surface contact angles of glossy paper without printed graphene ink (left) and with printed graphene ink (right). (c) Raman spectrum of glossy paper with printed graphene ink. (d) XPS of glossy paper surface with printed graphene ink.