Figure 7
a FESEM images with dull stripes of PAA fabricated in 0.3 M oxalic acid under 40 V for 2 h and post-treated in 5 wt% H3PO4 at 30°C for 40 min, b and c blurry FESEM images of cross-section and top view of PAA fabricated in 0.3 M oxalic acid under 40 V and 0°C for 5 h