Figure 2: (a) An SEM image of the composite particles (b) SEM image taken after HF etching process (the scale bar represents 500 nm). (c) An FTIR spectrum of the composite nanoparticles where the blue line represents the composite particles and the red line is a sample of composite particles treated with HF. The box highlights the difference between the two spectra near 1104 cm-1 which corresponding to the asymmetrical vibration of the Si-O-Si bond.