Sol–gel synthesis and enhanced photocatalytic activity of doped bismuth tungsten oxide composite

•Co dopant results in the phase change from Bi2WO6 to Bi2WO6/Bi14W2O27 heterostructure.•Enhanced photocatalytic activity of Bi2WO6/Bi14W2O27 heterostructure.•Synergistic effects coming from the interactions between Bi14W2O27 and Bi2WO6

Pristine Bi2WO6 and Bi2WO6/Bi14W2O27 photocatalysts were synthesized by sol–gel method using Co(II) cation as dopant. The influence of Co dopant to the formation of Bi2WO6/Bi14W2O27 heterostructure composite was discussed. The photocatalytic activities of as-prepared samples were evaluated sufficiently by using rhodamine B as target organic pollutants under visible light. The as-prepared Bi2WO6/Bi14W2O27 heterostructure achieved enhanced optical absorption in the visible-light region, and exhibited much higher photocatalytic activities than that of pristine Bi2WO6. The optimum Bi/Co molar ratio and calcining temperature were also explored. The enhanced activities were attributed to the formation of heterostructure in suppressing the recombination of photo-generated carriers. The Co dopant species would participate to reduce the charge carrier recombination by acting as trapping sites for photogenerated charges. A possible photocatalytic mechanism over Bi2WO6/Bi14W2O27 heterostructure was proposed.

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