Revealing antimicrobial and contrasting photocatalytic behavior of metal chalcogenide deposited P25-TiO2 nanoparticles

Quantum dot (QD)-sensitized P25-TiO2 based nanocomposites were developed using the pseudo-successive ionic layer adsorption and reaction (p-SILAR) technique and then applied in the photocatalytic degradation of an azo-type dye under visible and ultraviolet (UV) irradiation. The presence of PbS and CdS QDs on the P25-TiO2 nanoparticles facilitated visible light absorbance by P25-TiO2 and increased the photocatalytic activity under visible irradiation, whereas the efficacy of P25-TiO2 as a photocatalyst was reduced under UV light. We confirmed the successful deposition of PbS and CdS QDs on TiO2 under analogous QD sensitization conditions with p-SILAR, and showed that the PbS QD-sensitized TiO2 nanocomposite (TPbS) harvested more visible light than the CdS QD-sensitized TiO2 nanocomposite (TCdS), thereby resulting in greater dye degradation under visible light. In particular, TPbS degraded (similar to)57% of the dye acid orange-56 and TCdS degraded 16%. The nanocomposites exhibited antimicrobial activity against Bacillus subtilis (B. subtilis) where the most effective antimicrobial agent with the highest activity was TCdS.