Laser Plasma Induced TiO2 Nanoparticle Synthesis in Water and Particle Characterization

Nanofluids with nanoscale colloidal suspensions having condensed nanomaterials have been found to show highly enhanced physical, chemical, thermal, and transport properties and signify great potential in many fields. In this paper, laser-induced plasmas at liquid-metal phase boundaries are investigated for titanium oxide (TiO₂) nanoparticle synthesis in water without any surfactants. The nanoparticles are generated using 1064 nm NdYAG laser ablation in a water confined plasma with 1.5 J laser energy pulsed at 10 Hz for 4 min, which resulted in nanoparticles of size ranging from 5 to 35 nm. The synthesized TiO₂ nanoparticles in water are characterized for their sizes, surface morphology, crystalline structures, and elemental compositions. The dynamic light scattering (DLS) measurements show the synthesized TiO₂ nanoparticles have an average size of 18 nm. The scanning electron microscopy (SEM) measurements show TiO₂ nanoparticles exhibit isolated and agglomerated nanoparticles with near-spherical and irregular surface morphologies. The Transmission electron microscopy (TEM) measurements show TiO₂ nanoparticles with near-spherical and irregular shapes, and the average size of the nanoparticles is ~17 nm. The selected area electron diffraction (SAED) measurements show single and poly crystalline structures present in the TiO₂ nanoparticles. The energy-dispersive X-ray spectroscopy (EDX) measurements show the purity of TiO₂ nanoparticles with identification of Ti and O elements. The X-ray diffraction (XRD) measurements confirm that the TiO₂ nanoparticles are crystalline in nature and confirmed the presence and coexistence of two crystal phases of TiO₂ nanoparticles, such as anatase and rutile phases, and estimated nanoparticle size in the range between 11 and 31 nm.