Sol–gel synthesis of silicon oxide (SiO2) nanoparticles: exploring gas sensing and photocatalytic applications

Abstract In this research, silicon oxide (SiO 2 ) nanoparticles (NPs) were synthesized using the sol–gel method. The synthesized materials were characterized through various techniques. Fourier transform infrared spectroscopy (FTIR) revealed the absorption band corresponding to Si–O–Si bonds. Ultraviolet–visible (UV–Vis) spectroscopy analysis indicated a band gap energy of 5 eV. X-ray diffraction (XRD) analysis displayed a broad peak, confirming the amorphous nature of the material. Field emission scanning electron microscopy (FESEM) further demonstrated a spherical morphology of the SiO 2 NPs. The photocatalytic degradation of MB dye using SiO 2 NPs has been examined, revealing promising and improved degradation properties. Even a small amount of SiO 2 NPs achieved around 69.20% degradation of MB within 240 min, with the rate constant for the material being 0.001 min −1 . The gas sensing properties of the SiO 2 NPs were tested on domestic gas sensor units for different gases, including ethanol, methanol, CO 2 , LPG, H 2 S, NH 3 , O 2 , and Cl 2 , at temperatures ranging from room temperature to 300 °C. Among these materials, SiO₂ NPs displayed the strongest response to H₂S gas, showing outstanding gas-sensing performance at a concentration of 100 ppm. The response time was 18 S, with a quick recovery time of approximately 22 S. Graphical Abstract