Laser ablation-assisted synthesis of tungsten sub-oxide (W17O47) nanoparticles in water: effect of laser fluence

Tungsten sub-oxide (W17O47) nanoparticles were produced for the first time, via pulsed laser ablation of a pure tungsten target in distilled water. The beam of a Q-switched Nd:YAG laser of 1064 nm wavelength with 0.6, 0.8, 1.2 and 1.4 J/cm(2) fluences was employed to irradiate the target. Produced nanoparticles were characterized using field emission scanning electron microscopy coupled with energy dispersive spectrometry, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), UV-Vis absorption spectroscopy and room temperature Photoluminescence (PL). XRD patterns revealed that all samples possess the monoclinic structure corresponding to W17O47 phase. With increasing the laser fluence, the average size of the nanoparticles increased and subsequently, their band gap energy decreased. The PL spectra of the samples show the presence of oxygen vacancies or defects.