Effect of Hydrothermal Reaction Time on Size of Bismuth Oxide Nanoparticles Synthesized via Hydrothermal Method

Bismuth oxide (Bi2O3) nanoparticles were successfully synthesized using the cost-effective hydrothermal method. Hydrothermal reaction time was varied from 10 min, 20 min, 30 min, and 1 hour at 60 degrees C. The as-synthesized nanoparticles (NPs) were characterized by X-ray Diffractometer (XRD), Field Emission Scanning Electron Microscope (FESEM), Energy-Dispersive X-ray spectroscopy (EDX) and Fourier Transform Infra-Red (FTIR). The formation of pure phase Bi2O3 was confirmed from XRD analysis of each sample. The crystallinity of Bi2O3 increased with increasing hydrothermal reaction time due to formation of larger particle size with increasing hydrothermal reaction time. Longer reaction time allows more ions diffusion and form larger nanoparticles (NPs). Observation using FESEM showed Bi2O3 is in the form of rods. The diameter of Bi2O3 rods increased from 70 nm to 100 nm with increasing hydrothermal reaction time from 10 min to 1 hour. From EDX analysis, only Bi and O peaks were observed, suggesting that the NPs are of high purity. This result is consistent with the XRD analysis. The FTIR spectrum showed the absorption band at 845 cm(-1) which is attributed to Bi-O-Bi bond, and the strong absorption band recorded at 424 cm(-1) that is due to the stretching mode of Bi-O.