A tuneable bioinspired process of Pt-doping in TiO2 for improved photoelectrochemical and photocatalytic functionalities

The boom in health care facilities and the ongoing pandemic accelerate the production of pharmaceutically active compounds along with the generation of tons of hazardous pharmaceutical waste and billion gallons of wastewater. Therefore, the destruction of pharmaceutically active agents must be performed before it is disposed-off into the environment. In this study, a visible light driven Pt-doped TiO2 photocatalyst was synthesized via a tuneable bioinspired and steamed autoclaving method. Bio-analytes found in S. edule fruit extract were employed for Pt doping in Degussa P-25 TiO2, and it exhibited a superior photocatalytic functionality over chemically doped TiO2. Doping took place in two steps as Pt(IV)→Pt(II)→Pt(0) with its incorporation into TiO2 lattice with 91% relative abundance of Pt(0). Pt-doping decreased the charge recombination, and the reduction of Ti(IV)→Ti(III) caused the oxygen vacancies. Bandgap was reduced to 3.02 eV for mesoporous Pt1.47/TiO2 (Pt 1.47% w/w, 22.65 nm, zeta potential −13.3 mV at pH7). Hydrophobic Pt0/TiO2 (120.8°) particles became hydrophilic with Pt-doping (Pt0.49–2.43/TiO2, 46.4°−23.9°) facilitating free-radical formation. The photocurrent density of Pt1.47/TiO2 (5 on/off light cycles at 20 s intervals) was increased by about 8 folds in comparison to Pt0/TiO2. About 2 folds increase in CIP degradation (85.5 ± 0.94%) and quantum yield (21.05 ± 0.23%) were achieved under 50 W visible light within 180 min at the optimized pH of 5. Pt1.47/TiO2 was recovered and reused, and only 10.4% reduction in degradation efficiency was noted in the 5thcycle. Furthermore, degradation products were identified using mass-spectroscopy, and the mechanism of CIP decomposition is proposed and validated. [Display omitted] •A new bioinspired-steamed autoclaving method developed to synthesize Pt-doped TiO2.•Pt-doping took place as Pt(IV)→Pt(II)→Pt(0) with 90% Pt(0) abundance.•Bandgap of optimal Pt1.47/TiO2 (1.47% w/w) of 3.02 eV with improved functionality.•2-folds increase in Ciprofloxacin degradation and quantum yield under visible light.•Photocatalytic degradation in three different pathways with 17 intermediates.