Two-dimensional Bi2WxMo1−xO6 solid solution nanosheets for enhanced photocatalytic toluene oxidation to benzaldehyde.

Two-dimensional (2D) Bi 2 WO 6 , Bi 2 MoO 6 , and Bi 2 W x Mo 1− x O 6 (x = 0.1, 0.3, 0.5, 0.7, and 0.9) solid solution photocatalysts were synthesized using the hexadecyl trimethyl ammonium bromide-assisted hydrothermal method. All of the samples displayed a morphology of irregularly rectangular nanosheets with a thickness of 7.0–17.4 nm. The photocatalytic performance of Bi 2 W x Mo 1− x O 6 was much better than that of Bi 2 MoO 6 or Bi 2 WO 6 for the selective oxidation of toluene, with the Bi 2 W 0.3 Mo 0.7 O 6 solid solution showing the highest benzaldehyde formation rate (1663 μmol/(g h)), which was about 1.95 and 2.83 times higher than those obtained over Bi 2 MoO 6 and Bi 2 WO 6 , respectively. Furthermore, 91% benzaldehyde selectivity and excellent stability were also achieved over Bi 2 W 0.3 Mo 0.7 O 6. The enhancement in photocatalytic activity of Bi 2 W 0.3 Mo 0.7 O 6 was attributable to the balance of fast charge kinetics and optimized energy band structure. The results of the reactive species trapping and active radicals detection experiments reveal that the photogenerated holes, superoxide species, and carbon-centered radicals might play the important roles in the generation of benzaldehyde, and the possible photocatalytic toluene oxidation mechanisms over Bi 2 W 0.3 Mo 0.7 O 6 were accordingly proposed. [Display omitted] • 2D Bi 2 W x Mo 1− x O 6 solid solution nanosheets are synthesized via the CTAB-assisted hydrothermal route. • Bi 2 W 0.3 Mo 0.7 O 6 shows the highest benzaldehyde formation rate. • Bi 2 W 0.3 Mo 0.7 O 6 exhibits faster charge separation and transfer efficiencies than Bi 2 WO 6 and Bi 2 MoO 6. • Photogenerated holes, superoxide, and carbon-centered radicals govern the photocatalytic reaction. • Good activity of Bi 2 W 0.3 Mo 0.7 O 6 is due to the balance of fast charge kinetics and optimized energy band structure. [ABSTRACT FROM AUTHOR]