TiO2-Pt composite photocatalyst for photodegradation and chemical reduction of recalcitrant organic pollutants

In this study, visible light driven TiO2-Pt composite photocatalyst is developed for efficient removal of recalcitrant pollutant, namely 4-nitrophenol and Rhodamine B from water environment by a process of chemical reduction and photocatalytic degradation, respectively. The catalysts were synthesized by hydrothermal method followed the chemical reduction process. Obtained catalysts were characterized by XRD, UV-DRS, Raman, SEM, PL, TPRL and EIS measurement It was observed that increasing weight percentage of Pt nanoparticle loading on TiO2 resulted in a significant increase in photocatalytic degradation of Rhodamine B and reduction of 4-nitrophenol to 4-aminophenol. In that TiO2 photocatalyst loaded with 5wt% Pt exhibited 4.5 fold increase in photocatalytic pursuance of Rh.B and 45 fold increase in 4-nitrophenol reduction on comparisons to pristine TiO2. ESI-MS analysis of products of photocatalysis confirms the degradation of Rh.B. Further, the photocatalyst exhibited good reusability when tested over five cycles of consecutive degradation of Rh.B. The enhancement in photocatalytic pursuance is attributed to its strong adsorption ability towards Rh.B and 4-NP, increased charges carrier separation, high surface area, good light harvesting ability and increased electron transport However, increasing the platinum nanoparticles loading beyond the 5wt% threshold found to limit the catalytic efficiency of the composites. It is inferred that reduction in light absorption ability and suppression of active sites of TiO2 nanoparticles by Pt particles is attributed to decreased photocatalytic pursuance beyond the threshold concentration. Further, demonstration of simultaneous reduction 4-NP and degradation of Rh.B reiterate the potential applicability of this catalyst for treatment of complex industrial effluents.