Enhanced photocatalytic performance of BiVO₄ in aqueous AgNO₃ solution under visible light irradiation

Graphical abstract: Ag⁺ ions enhanced photocatalytic activity of BiVO₄ under visible light irradiation. - Highlights: • The presence of Ag⁺ ions enhanced the photodegradation activity of BiVO₄. • Photoreduction of Ag deposited on the BiVO₄ surface was obtained. • Luminescence and electrochemical results elucidated the photocatalytic mechanism. • Holes and oxygen radicals were the main reactive species generated by BiVO₄/Ag⁺. • Used BiVO₄/Ag⁺ exhibited photocatalytic antibacterial activity toward E. coli. - Abstract: Monoclinic-phase bismuth vanadate (BiVO₄) with a 2.468 eV band gap exhibited enhanced synergic photodegradation activity toward methylene blue (MB) when combined with silver ions (Ag⁺) in an aqueous solution under visible light irradiation. The mass ratio of AgNO₃ to BiVO₄ and the calcination temperature were discovered to considerably affect the degradation activity of BiVO₄/Ag⁺. Superior photocatalytic performance was obtained when BiVO₄ was mixed with 0.01%(w/v) AgNO₃ solution, and complete degradation of MB was achieved after 25 min visible light irradiation, outperforming BiVO₄ or AgNO₃ solution alone. The enhanced photodegradation was investigated using systematic luminescence measurements, electrochemical impedance spectroscopy, and scavenger addition, after which a photocatalytic mechanism for MB degradation under visible light irradiation was identified that involved oxygen radicals and holes. This study also discovered the two dominating processes involved in enhancing the electron–hole separation efficiency and reducing their recombination rate, namely photoreduction of Ag⁺ and the formation of a BiVO₄/Ag heterojunction. The synergic effect between BiVO₄ and Ag⁺ was discovered to be unique. BiVO₄/Ag⁺ was successfully used to degrade two other dyes and disinfect Escherichia Coli. A unique fluorescent technique using BiVO₄ and a R6G solution to detect Ag⁺ ions in water was discovered.