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Pseudo-successive ionic layer adsorption and reaction (p-SILAR) process was opted for deposition of PbS/CdS and CdS/PbS quantum-dots (QDs) on TiO2 to combine light absorbing tendency of PbS and CdS QDs which evolved significant photocatalytic behavior in TiO2 under visible light irradiation. It was shown that the resultant TiO2/PbS/CdS hierarchical nanocomposite exhibited better photo-electrochemical behavior than TiO2/CdS/PbS, ensuing ∼42% higher degradation of acid orange-56 than the latter and ∼65% higher than pristine TiO2. In addition, both nanocomposites resulted promising antibacterial activity against Escherichia coli (E. coli). Particularly TiO2/PbS/CdS showed much greater inhibition zone (∼14 mm) than TiO2 (∼8 mm).

Simply by elevating the successive ionic layer adsorption and reaction temperature for ZnS deposition, we successfully demonstrated improved photostability of PbS-based quantum dot-sensitized solar cells (QDSCs) which was credited to efficient surface coverage of ZnS over PbS QDs and TiO2. Using open-circuit voltage decay and cyclic voltammetry techniques distinctly, it was affirmed that the back electron transfer at TiO2/PbS/electrolyte interface was reduced. Superior deposition of ZnS in terms of surface coverage not only exhibited increase in photocurrent density (from 20.7 mA/cm2 to 22.3 mA/cm2) and power conversion efficiency (from 3.1% to 3.4%), it also stabilized the normalized current significantly.