Fig. 1
From: Perfect proton selectivity in ion transport through two-dimensional crystals
Proton transport through 2D crystals studied using aqueous solutions. a Examples of I–V characteristics for 1 M HCl. Bottom inset: zoom-in. Top inset: electron micrograph of a suspended hBN membrane (aperture diameter, 2 µm). b Concentration dependence of the areal conductivity σ for monolayer hBN. Gray area indicates our detection limit given by parasitic leakage currents. Error bars: SD from different measurements. Dashed line: best linear fit to the data. Top inset: atomic force microscopy (AFM) height profile of an ‘inflated nanoballoon’. Here, graphene monolayer seals a micrometer-sized cavity containing pressurized Ar. The pressure difference across the membrane makes it to bulge up. Lateral scale bar, 1 μm; color scale, 130 nm. Bottom inset: AFM line trace taken along the blue dotted line in the top inset
