Engineering of oxygen vacancy as defect sites in silicates for removal of diverse organic pollutants and enhanced aromatic alcohol oxidation

Abstract

Efficient charge separation of the generated excitonic pair upon light irradiation is a crucial step in determining the efficiency of photocatalytic activity. Oxygen vacancy sites are known to overcome poor charge segregation. Herein, a hydrothermal approach was utilized to synthesize oxygen vacancy rich Bi2SiO5 nanoparticles (BSO NPs) with superior charge separation. Halide anion incorporation resulted in generation of oxygen vacancy sites along with a preferential growth of monoclinic over tetragonal phase. This phase transformation is advantageous as the monoclinic phase shows enhanced photocatalytic activity compared to the tetragonal. The synergetic effect of halide ions and oxygen vacancy sites on the surface led to increased photocatalytic activity arising from (1) enhanced light absorption towards visible spectrum from ultraviolet, (2) reduced bandgap, (3) surge in charge migration, and (4) increased surface area of the BSO NPs. Oxygen vacancy rich halide incorporated Bi2SiO5 NPs showed up to 12 times improved photocatalytic rate over pristine towards toxic dye pollutants. Photocatalytic tetracycline degradation mechanism was also studied displaying up to 83% degradation within 180 min of solar light irradiation. In addition, the developed photocatalyst is efficient towards synthesis of benzaldehyde from benzyl alcohol with high yield up to 40% within 4 h.