Hydrothermal synthesis of Z-scheme Bi2WO6/Bi2MoO6 heterojunctions for the enhanced photoelectrocatalytic performance of TiO2 NTs: Structure, activity and mechanism approach

In this paper, the direct Z-scheme Bi2WO6-Bi2MoO6 heterojunctions were constructed by the simple hydrothermal deposition on TiO2 nanotube arrays (TiO2 NTs). The results revealed Bi2WO6/Bi2MoO6 heterojunctions dramatically enhanced the solar absorption and slowed the electron recombination, which improved the photoelectrocatalytic pollutant removal property, and center dot OH and center dot O-2 radicals were the decisive active species. Moreover, the TiO2 NTs/Bi2WO6-Bi2MoO6 photoelectrode exhibited excellent photoelectric conversion and photoelectrocatalytic H-2 evolution properties, much higher than the data of TiO2 NTs/Bi2WO6 and TiO2 NTs/Bi2MoO6 photoelectrodes. The visible light photoelectrocatalytic H-2 evolution rate of TiO2 NTs/Bi2WO6-Bi2MoO6 photoelectrode was 38.03 mu mol center dot h(-1)center dot cm(-2), and it still showed high photocatalytic activity after several experimental cycles. The outstanding photocatalytic activity of TiO2 NTs/Bi2WO6-Bi2MoO6 sample provides a referential template of the Z-scheme heterojunction construction for the application in photocatalytic pollutant removal and H-2 evolution.

Automated summary

In this study, direct Z-scheme Bi2WO6-Bi2MoO6 heterojunctions were fabricated on TiO2 nanotube arrays using a simple hydrothermal deposition method. The Bi2WO6/Bi2MoO6 heterojunctions significantly improved solar absorption and suppressed electron recombination, leading to enhanced photoelectrocatalytic pollutant removal. The active species responsible for this effect were found to be ·OH and ·O-2 radicals. The TiO2 NTs/Bi2WO6-Bi2MoO6 photoelectrode exhibited excellent photoelectric conversion and photoelectrocatalytic H-2 evolution properties, surpassing those of TiO2 NTs/Bi2WO6 and TiO2 NTs/Bi2MoO6 photoelectrodes. The visible light photoelectrocatalytic H-2 evolution rate of the TiO2 NTs/Bi2WO6-Bi2MoO6 photoelectrode was measured to be 38.03 μmol·h(-1)·cm(-2), and it displayed sustained high photocatalytic activity after several experimental cycles. The exceptional photocatalytic performance of the TiO2 NTs/Bi2WO6-Bi2MoO6 sample provides a valuable reference for the construction of Z-scheme heterojunctions in photocatalytic pollutant removal and H-2 evolution applications.