Bi spheres SPR-coupled Cu2O/Bi2MoO6 with hollow spheres forming Z-scheme Cu2O/Bi/Bi2MoO6 heterostructure for simultaneous photocatalytic decontamination of sulfadiazine and Ni(II)

Environmental problem on the coexistence of organic pollutants and heavy metals in surface waters has become increasingly serious. Few relative researches have focused on their simultaneous decontamination. Herein, a ternary plasmonic Z-scheme Cu2O/Bi/Bi2MoO6 heterojunction was synthesized via two-step route followed by a wet-impregnation, where Bi spheres coupled with Cu2O particles were anchored on the surface of Bi2MoO6 with hollow microflower spheres. The composites were characterized via various measurements. The excellent photocatalytic activity of Cu2O/Bi/Bi2MoO6 displayed in single sulfadiazine (SDZ) oxidation or Ni(II) reduction, and their simultaneous removal. The degradation pathway for SDZ was investigated via LC–MS and Gaussian theory. DFT and FDTD calculations confirmed the electronic structural characteristics in the Cu2O/Bi/Bi2MoO6 heterostructure and the induced electric field enhancement around nearly touching Bi spheres. A possible photodegradation mechanism of the as-prepared photocatalyst was elucidated via combining scavenger experiments with EPR technique. The results suggested h+, •O2− and •OH all participated in SDZ oxidation, which verified that Z-Scheme electron transfer was major manner in Cu2O/Bi/Bi2MoO6, while •O2− and e−acted on Ni(II) reduction. The improved photocatalytic activity of Cu2O/Bi/Bi2MoO6 could be ascribed to the unique Z-scheme electron transfer among Cu2O, Bi and Bi2MoO6, particularly SPR and local electric field near Bi spheres.