Defect-mediated time-efficient photocatalytic degradation of methylene blue and ciprofloxacin using tungsten-incorporated ternary perovskite BaSnO3 nanoparticles.

Photocatalytic water purification has been extensively explored for its economic, eco-friendly, and sustainable aspects. In this study, tungsten (W) incorporated BaSn1-xWxO3 (x = 0 to 0.05) nanoparticles synthesized by facile hydrogen peroxide precipitation route has been demonstrated for photocatalytic degradation of methylene blue (MB) dye and ciprofloxacin (CIP) antibiotic. The structural analysis indicates the presence of hybrid composite-like nanostructures with reduced crystallinity. Optical studies reveal blueshift in bandgap and decrease in oxygen vacancy defects upon W-incorporation. Pure BaSnO3 shows overall enhanced photocatalytic activity towards MB (90.22%) and CIP (78.12%) after 240 min of white LED light and sunlight irradiation respectively. The 2 % W-incorporated BaSnO3 shows superior photocatalytic degradation of MB (26.89%) and CIP (45.14%) within first 30 min of irradiation confirming the presence of W to be beneficial in the process. The free radical study revealed the dominant role of reactive hole (h+) and oxygen radical (O2•-) species during photodegradation and their intermediates are investigated to elucidate the degradation mechanism of MB within 30 min of irradiation. This study is promising towards developing defect mediated and time-efficient photocatalysts for environmental remediation.

Prickly pear fruit extract as photosensitizer for dye-sensitized solar cell.

In this study, we have explored prickly pear fruit extract as a photosensitizer in dye-sensitized solar cells (DSSC). The photosensitizer was isolated from prickly pear fruits by extraction method using ethanol as solvent. Structural, morphological and optical properties of prickly pear extract characterized by XRD, SEM, UV-VIS-DRS, FTIR spectra, respectively. UV-VIS absorption and FTIR spectra of prickly pear fruit extract confirm the presence of betacyanin and hydroxyl groups anchoring onto the TiO2 surface. The absorption maxima at 534 nm in the visible region is prominent. The presence of betacyanin in the extract is indicative that the dye will be useful as a sensitizer in DSSC. Reflectance edge of TiO2 is red-shifted upon the adsorption of natural dye. The XPS analysis showed the charge state of hydroxyl (O-H) groups that are attached with the natural dye adsorbed onto the surface of TiO2. The fabricated DSSC had a conversion efficiency (ɳ) of 0.56% with highest fill factor (FF) of 0.85, open-circuit voltage (Voc) of 0.56 V and short circuit-current density (Jsc) with 1.17 mA/cm2. The value obtained for the fill factor is promising to further explore the prickly pear extract for applicability in DSSC by improving the efficiency.