Fig. 7: FESEM images of CNT-bots at different stages.

Image a shows the pristine –COOH-functionalsed MWCNT at ×100,000 magnification, and the inset shows the same image at a higher magnification. Image b shows the Fe²⁺-doped MWCNT at ×30,000 magnification, and the inset shows the same at ×10⁵ magnification. Image c shows the FeONP-doped MWCNT at ×30,000 k magnification, and the inset shows the same at ×10⁵ × magnification. Image (d) shows the FeONP- and Fe²⁺-doped MWCNTs at 30000 × magnification, and the inset shows the same at 10⁵ magnification. Images e and f show, at lower magnification, the morphology of the Janus-CNT-bot in which one side is FeONP/Fe²⁺-doped MWCNTs, and the other side is magnesium-coated FeONP/Fe²⁺-doped MWCNTs.