Enhanced Visible-Light-Driven Photocatalytic Activity by 0D/2D Phase Heterojunction of Quantum Dots/Nanosheets on Bismuth Molybdates

The development of semiconductor heterojunctions with strong light response and high charge separation efficiency is highly desired for addressing the global environmental and energy-related concerns. Herein, we present a new type of zero-dimensional (0D)/two-dimensional (2D) phase junction of bismuth molybdate Bi4MoO9 quantum dots (QDs)/Bi2MoO6 nanosheets (NS's) to boost the interfacial charge transfer and electron conductivity for excellent visible-light-driven photocatalytic activity. Photocurrent and Mott–Schottky spectroscopy demonstrate that the strong coupling between 0D Bi4MoO9 QDs and 2D Bi2MoO6 NS's via phase heterojunctions could effectively tune the semiconductor work function for reducing the interfacial Schottky barrier by 0.05 eV, which greatly shortens the effective charge-transfer length and increases the number of photoexcited electrons in the conduction band of Bi4MoO9 QDs. Hence, the as-obtained 0D/2D phase junctions of bismuth molybdates achieve excellent photocatalytic degradation of RhB under visible-light irradiation (λ > 420 nm) and increase the catalytic efficiency 13–23 times compared to that of pristine Bi4MoO9 and Bi2MoO6. This work offers a new concept to construct multifunctional phase junctions for the design of an efficient photocatalyst in the application of solar energy.