Fig. 1: Typical non-porous and porous morphology of printed GO aerogel filaments.

a Schematic demonstration of directly 3D printing GO ink into liquid nitrogen. b, c Distribution of (b) velocity and (c) shear stress at the nozzle in the printing of pure GO aerogel, printed at 300 μL/min with nozzle of 0.413 mm. d, e Surface SEM figures of as-printed pure GO aerogel. f–h Cross-sectional SEM figures of (f) section, (g) edge of section, and (h) centre of section of as-printed pure GO aerogel. i, j Distribution of (i) velocity and (j) shear stress at the nozzle in the printing of aerogel with ascorbic acid (160 mM), printed at 300 μL min⁻¹ with nozzle of 0.413 mm. k, l Surface SEM figures of as-printed aerogel with 160 mM AA. m–o Cross-sectional SEM figures of the (m) section, (n) edge of section, and (o) centre of section of as-printed aerogel with 160 mM AA. Scale bars 100 μm. Distribution of velocity and shear stress are obtained by CFD simulation (see Methods).