Impact of Dual Functionalities of Mo‐Doped BiFeO3 Decorated with Bi4MoO9 Heteroatoms for Piezo‐Photocatalytic Activity

Piezocatalysts have shown great promise for advanced and green hydrogen generation. However, their application is typically limited owing to the rapid charge recombination and sluggish charge transfer rate of piezo‐induced charge carriers. The present work aims to address the preceding limitations by controlled synthesis of a representative piezocatalytic material, BiFeO3 doped with Mo atoms and decorated with Bi4MoO9 (BMO) heteroatoms using a sol‐gel method. The work revealed that the substitutional doping of Mo on BFO (BFMO) induced a shallow energy level near the conduction band that acted as trapping state to a) suppress charge recombination, b) enhance charge mobility transporting to the surface, c) modulate band alignment, and d) lower the energy barrier for surface reaction. Also, the BFMO/BMO heterostructures induced electrical band bending that led to the formation of an electric‐potential gradient, hence promoting charge carrier separation and transfer. The nanostructures with 0.5 mol % Mo (Mo‐5) demonstrated 4‐times faster piezocatalytic dye degradation rate (k = 0.032 min‐1) compared to pristine BFO (0.009 min‐1). Further, the Mo‐5 exhibited a 45% higher piezocatalytic H2 production rate compared to pristine BFO with cocatalyst‐free. Further, the work demonstrates the lack of synergy between piezocatalytic and photocatalytic processes due to Auger recombination effects.