Solvothermal synthesis of Ag hybrid BiPO₄ heterostructures with enhanced photodegradation activity and stability

In this study, Ag hybrid BiPO₄ (Ag/BiPO₄) heterostructures were synthesized using a solvothermal method. The morphologies and optical properties of the Ag/BiPO₄ heterostructures were drastically different from those of BiPO₄ and were highly dependent on the AgNO₃:BiPO₄ weight percent during the synthesis. The three formulated heterostructures were evaluated for their photocatalytic degradation of methylene blue (MB) under UV light illumination; the 0.5%Ag/BiPO₄ heterostructure was observed to result in 99% degradation of MB within 60min, a remarkably higher level of photodegradation activity than the levels caused by TiO₂ and BiPO₄. Furthermore, even after use for five cycles of MB degradation, the 0.5%Ag/BiPO₄ heterostructure showed no observable loss in photodegradation activity and no change in XRD patterns, demonstrating its chemical and structural stability. According to the results of a systematic experimental investigation, the enhanced photodegradation activity of this Ag/BiPO₄ heterostructure could be ascribed to the high position of its valence band and the highly efficient separation of photogenerated electrons and holes. Moreover, hydroxyl radicals and holes were found to be the major reactive species. Successful photodegradation of standard dye solutions, including acid blue 1, methyl orange, fast green, rhodamine B, rhodamine 6G, and MB, in real water samples was demonstrated with the 0.5%Ag/BiPO₄ heterostructure, providing clear evidence of its utility for treating waste water containing organic dyes.