Fig. 2

Characterization of MXene organic inks. a Photos of various MXene organic inks. b TEM image of MXene nanosheets from NMP ink. Inset shows the selected area electron diffraction (SAED) pattern. Scale bar = 200 nm and = 2 1/nm in the inset. c AFM image and d the corresponding height profiles along the lines in (c). e Viscosity plotted as a function of shear rates for different MXene organic inks. The data were fitted according to the Ostwald-de Waele power law: \(\eta = k\gamma ^{n - 1}\), where k and n are the consistency and shear-thinning index, respectively⁴⁶. f Scheme of fine resolution of inkjet printing of MXene organic inks. The curved green lines represent MXene nanosheets while the arrows indicate the inward (blue) and outward (red) flows of the droplet. Three critical steps, namely, stable jetting, good substrate wetting and droplet drying, control the spatial uniformity of the resultant printed patterns/lines. SEM image of the inkjet-printed MSC using, g the NMP ink (inset shows the whole device) and h the ethanol ink. Scale bar in (g) and (h) = 200 µm and = 1 cm in the inset of (g). The distances between the two arrows in (g) and (h) are 50 µm and 130 µm, respectively. i width variation of inkjet-printed MXene lines printed using NMP (top) and ethanol (bottom) inks