Ag, Au and Pt decorated TiO2 biocompatible nanospheres for UV & vis photocatalytic water treatment

Abstract Spherical noble metal-titanium dioxide nanoparticles (Pt/TiO2, Au/TiO2 and Ag/TiO2) were synthesized using laser pyrolysis (LP) followed by wet impregnation and reduction methods. Also, aerosol-assisted LP was used for direct Ag/TiO2 generation. Nanomaterial morpho-structural characteristics were evaluated using transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and UV–Vis diffuse reflectance spectroscopy (DRS). Titania based nanocomposites, with (0.01–0.28 at %) noble metal loading, exhibit band gap reduction (down to 2.77 eV) due to two cumulative factors: near atmospheric pressure LP synthesis and metal addition on TiO2 nanoparticle surface, via Surface Plasmon Resonance (SPR). Nanocomposites photocatalytic performance, in UV and Vis range, attests LP synthesized Ag-catalyst as the highly effective product in aqueous methyl orange (MO) total photodegradation (with rate constants of 28.74 × 10−3 min−1 for UV and 16.78 × 10−3 min−1 for Vis). Moreover, LP samples biocompatibility tests indicate good biocompatibility with human lung cells (MRC-5), their toxicity being diminished when compared with commercially P25 Degussa. This study reveals that LP technique generates lower band gap biocompatible titania photocatalysts. LP-titania noble metal decoration enhances UV and Vis pollutant photodegradation efficiencies, contributing to the development of a low risk environmentally-friendly method for water treatment.