Synthesis and characterization of SnO2 nanoparticles using an autoclave-assisted hydrothermal method

Tin oxide (SnO₂) nanoparticles have been receiving increasing attention due to their structural, electrical, optical properties and diverse applications. In this study, nanoparticles were synthesized via a hydrothermal route using an autoclave, where the reaction temperature was systematically varied to control and tune the morphology of the nanomaterials. X-ray diffraction (XRD) analysis identified the crystal structure of as-synthesized SnO₂ nanoparticles. X-ray diffraction (XRD) analysis confirmed the crystalline tetragonal rutile SnO₂ nanoparticles. But average crystallite sizes were found to be ⁓15 and ⁓3 nm for hydrothermal temperatures of 110°C and 150°C respectively. A significant reduction in particle size was observed with increasing hydrothermal temperature. Vis spectroscopy revealed stronger absorption for SnO₂ nanoparticles synthesized at 110°C. Strong absorption was observed in the shorter wavelength region for 110°C, in the contrary that was observed in the longer wavelength region for 150°C.The estimated band gap energies were 1.2 eV and 1.6 eV for temperature of 110°C and 150°C respectively, that identified an increase in band gap with increasing temperature. Overall transmittance was comparatively lower for SnO₂ 110°C. Specifically, higher transmittance was exhibited in the lower and higher energy region for hydrothermal temperature of 110 °C and 150 °C respectively. Energy transmission was higher for lower band gap and that was lower for higher band gap. Fourier transform infrared (FT-IR) spectroscopy identified a characteristic absorption peak at 628 cm⁻¹ corresponding to SnO₂ stretching vibrations. Overall, hydrothermal temperature significantly influenced the crystallite size, optical absorption & transmission, and band gap of the synthesized SnO₂ nanoparticles. These tunable properties suggest that the prepared SnO₂ nanoparticles may be promising candidates for applications in photocatalysis, optoelectronic devices, transparent conducting materials, and renewable energy technologies.