Selective synthesis of visible light active γ-bismuth molybdate nanoparticles for efficient photocatalytic degradation of methylene blue, reduction of 4-nitrophenol, and antimicrobial activity

Abstract

In this study, we have reported selective synthesis of bismuth molybdate (γ-Bi₂M₂O₆) nanoparticles (NPs) under different pH conditions for photocatalytic degradation of methylene blue (MB), reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and antimicrobial activities. The synthesis of pure phase γ-Bi₂M₂O₆ at pH = 3 was confirmed by X-ray diffraction (XRD) and Raman analysis. A single hexagonal morphology was obtained at pH = 3 which shows the formation of the pure phase γ-Bi₂M₂O₆ NPs. The mixed morphologies (hexagonal and spherical) were observed at different pH values other than pH = 3. The bandgap energy of all the synthesized Bi₂M₂O₆ NPs is found in the visible region (2.48–2.59 eV). The photocatalytic activity of bismuth molybdate (BM) NPs was examined by the degradation of MB under visible light irradiation. Results show that 95.44% degradation efficiency was achieved by pure γ-Bi₂M₂O₆ NPs compared to mixed phases (γ-Bi₂M₂O₆, α-Bi₂M₂O₆ and β-Bi₂M₂O₆) synthesized at pH = 1.5 and 5. Moreover, the degradation efficiency of γ-Bi₂M₂O₆ was enhanced to 98.89% by the addition of H₂O₂. The effective catalytic activity of γ-Bi₂M₂O₆ was observed during the reduction of 4-NP to 4-AP by NaBH₄. Potential antibacterial and antifungal activity of γ-Bi₂M₂O₆ was observed, which gives a basis for further study in the development of antibiotics.