Structural and optical properties of grey and porous SiO2 nanoparticles

Highlights: • Grey and porous SiO₂ was firstly fabricated using a simple method in this work. • The microstructure and optical properties of this nanoparticles were well investigated. • At low frequency region, absorption coefficient (a) is in direct proportion to the imaginary component ${\left(2\epsilon ″\right)}^{\frac{1}{4}}$. -- Abstract: In this communication, XRD, TEM, SEM, XPS and Raman techniques are selected to probe the composition and microstructure of the porous G-SiO₂ nanoparticles. We find that BET surface area and average pore diameter are 49.336 m² g⁻¹ and 10.8 nm, and the porous nanoparticles with Si vacancies play an important role in expanding the absorption edge to the visible-light region. Besides, we first establish the relation between dielectric constant and optical absorption coefficient.