Fig. 3.

Electron microscopy images of the membrane hierarchical macro-structure and nano-structure. a Cross-sectional SEM image of the Anodisc support showing oriented ~50-nm-wide pore channels near the top surface (scale bar: 5 μm). b Plan-view TEM image of focused ion beam (FIB)-sectioned Anodisc surface showing complete filling of all Anodisc pore channels with ordered arrays of silica mesopores (scale bar: 100 nm). (Note: FIB sectioning served to etch the alumina leaving only the silica mesopore arrays. Silica mesopore arrays not perfectly aligned normal to imaging axis appear as stripe patterns). c Cross-sectional TEM image of the Anodisc surface showing oriented arrays of 8 nm diameter cylindrical mesopores filling the Anodisc pores (scale bar: 100 nm). d, e Higher magnification cross-sectional TEM image showing oriented array of 8 nm diameter cylindrical mesopores filling a single Anodisc pore (scale bar d: 100 nm; scale bar e: 50 nm). f Plan-view TEM image of silica mesopore array at membrane surface showing hexagonal close packing of cylindrical mesopores (scale bar: 20 nm)