Facile construction of a novel dual Z-scheme mixed phases BiFeO₃ heterojunction: For peroxymonosulfate activation toward efficient photodegradation of 4-nitrophenol and mechanistic insights

This study proposes a novel approach for preparing bismuth ferrite (BiFeO₃, BFO) with controlled crystal phase purity and morphology via a one-pot hydrothermal process using specific mineralizers (NaOH or KOH). The effects of these mineralizers on the crystal purity and photocatalytic efficiency of the catalyst were investigated. The XRD results revealed that KOH produced pure BFO, whereas NaOH yielded mixed-phase BFO (m-BFO) with secondary phases, including Bi₂O₃ and Bi₂Fe₄O₉. SEM analysis revealed that m-BFO exhibited a flake-like structure assembled into cubes, whereas pure BFO consisted of irregularly shaped agglomerated nanoparticles. The photocatalytic efficiency of the two catalysts was evaluated for the degradation of 4-nitrophenol (4-NP). The results showed that m-BFO exhibited outstanding photocatalytic degradation performance (92%) for 4-NP compared with pure BFO (22%). The enhanced photocatalytic efficiency of m-BFO was attributed to the construction of a dual-heterojunction Z-scheme within its structure and the presence of abundant surface oxygen vacancies. This study provides valuable insights into the synthesis of efficient dual-heterojunction Z-scheme photocatalysts via one-pot hydrothermal synthesis.