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

In this study, we have reported selective synthesis of bismuth molybdate (γ-Bi 2 M 2 O 6 ) 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-Bi 2 M 2 O 6 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-Bi 2 M 2 O 6 NPs. The mixed morphologies (hexagonal and spherical) were observed at different pH values other than pH = 3. The bandgap energy of all the synthesized Bi 2 M 2 O 6 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-Bi 2 M 2 O 6 NPs compared to mixed phases (γ-Bi 2 M 2 O 6 , α-Bi 2 M 2 O 6 and β-Bi 2 M 2 O 6 ) synthesized at pH = 1.5 and 5. Moreover, the degradation efficiency of γ-Bi 2 M 2 O 6 was enhanced to 98.89% by the addition of H 2 O 2 . The effective catalytic activity of γ-Bi 2 M 2 O 6 was observed during the reduction of 4-NP to 4-AP by NaBH 4 . Potential antibacterial and antifungal activity of γ-Bi 2 M 2 O 6 was observed, which gives a basis for further study in the development of antibiotics.