Figure 3. Low to high magnification SEM showing the increasing degree of porosity of PM CST nanoribbons as temperature increases, including sample heat-treated at 700 °C (a,b), 900 °C (c,d), and 1100 °C (e,f) (Scale bars for (a–f), respectively: 1 μm, 200 nm, 500 nm, 100 nm, 1 μm, and 100 nm).