Facile Hydrothermal Synthesis of Z-Scheme Bi 2 Fe 4 O 9 /Bi 2 WO 6 Heterojunction Photocatalyst with Enhanced Visible Light Photocatalytic Activity.

An efficient binary Bi2 Fe4 O9 /Bi2 WO6 Z-scheme heterojunction was fabricated through a facile hydrothermal route. The obtained Bi2 Fe4 O9 /Bi2 WO6 displays high catalytic activity for rhodamine B (RhB) photodegradation, and 100% of RhB was photodegraded by Bi2 Fe4 O9 (7%)/Bi2 WO6 within 90 min, which is much better than that by pure Bi2 Fe4 O9 and Bi2 WO6 . The effective photoinduced carrier separation, the broadened photoabsorption range, high oxidation capacity of hole, and the high reduction power of electron are in charge of the elevated catalytic activity because of the formed Z-scheme system. In addition, the effects such as pollutant concentration, pH, inorganic anions, and water sources exerted on photocatalytic performance were also investigated, and the results suggest that Bi2 Fe4 O9 /Bi2 WO6 still possesses a high photocatalytic performance. The free-radical trapping experiments and electron spin resonance spin-trapping technology disclose that hole (h+ ), hydroxy radical (• OH), and superoxide radical (• O2 - ) are cardinal active radicals in the catalytic system. In terms of the above experimental analysis, a possible photodegradation mechanism of the as-fabricated photocatalyst is thoroughly elucidated. In addition, the possible RhB photodegradation pathway is also raised in the light of the analysis of liquid chromatography-mass/mass spectrometry. In addition, Bi2 Fe4 O9 /Bi2 WO6 composite does not display dramatic reduction of the catalytic performance after five recycles. Thus, this study reveals that the as-obtained Bi2 Fe4 O9 /Bi2 WO6 catalyst has a great prospect for the environmental purification.