Modulation of the Internal Electric Field in Te-Doped Bi₂MoO₆ Nanosheets: Implication for the Photocatalytic Degradation of Rhodamine B and Photooxidation of Benzylamine

Abstract

Despite its considerable potential to address energy and environmental challenges, the practical application of photocatalysis is restricted by the limited efficiency of the photocatalysts. This research aims to improve the photocatalytic efficiency of Bi 2 MoO 6 by adjusting the internal electric field within the crystal lattice via Te doping. Te-Bi 2 MoO 6 nanosheets were prepared by a one-step hydrothermal method. Although the band gap energy and the long-range crystal structure are not affected upon doping, Te substitution provides several benefits to the performance of Bi 2 MoO 6 . First, the introduction of Te significantly reduces the thickness of the nanosheets, resulting in a larger surface area. Te states are also introduced into the conduction band, thereby increasing the carrier mobility. More importantly, the reduced cell parameters upon doping and the presence of Te in the lattice not only increase the potential difference between Bi−O and Mo(Te)−O layers in the lattice but also create an asymmetric potential difference. As a result, an internal electric field is enlarged, leading to increased carrier separation. Consequently, 5.0 mol % Tedoped Bi 2 MoO 6 could degrade 99.7% of Rhodamine B in 1 h under visible light, with 6.4 times higher rate constant than pristine Bi 2 MoO 6 . Additionally, the doped sample also exhibits about two times enhancement in benzylamine photooxidation (85% conversion vs 39% conversion) while maintaining excellent stability. Thus, this research highlights the efficacy of modulating the internal electric field through chemical modification as a viable strategy for enhancing the performance of photocatalysts.