Boosting of the piezoelectric photocatalytic performance of Bi2MoO6 by Fe3+ doping and construction S-scheme heterojunction using WO3

The excellent piezoelectric photocatalytic ability of the S-scheme heterojunction Bi2MoO6–0.02Fe/WO3. [Display omitted] •The origin of BMO ferroelectric property was determined by DFT.•Heterojunction with oxygen production was used to boost degradation capacity to organic pollutants.•The carrier separation was promoted by Fe3+ doping and constructing S-scheme heterojunction with WO3. Although self-polarized piezoelectric semiconductor photocatalysts significantly enhance the separation of internally generated photocarriers, their photocatalytic performance is constrained by insufficient internal polarisation and a wide bandgap. Additionally, the low concentration of oxygen in contaminated water limits the effectiveness of such photocatalysts. To the best of our knowledge, this study was the first to determine that the piezoelectric properties of Bi2MoO6 (BMO), was due to the polarisation displacement of the MoO6 octahedron that occurred along the x-axis, as revealed through density functional theory (DFT) calculations. Subsequently, the self-polarisation characteristics of BMO were enhanced and the bandgap was reduced through Fe3+ doping, as confirmed via atomic force microscopy, hysteresis loop measurements and DFT analysis, resulting in an increase in surface potential from 30.41 to 46.80 mV. Furthermore, an S-scheme WO3/Bi2MoO6:Fe3+ heterojunction was developed to improve the surface separation of photoelectron–hole pairs. The piezoelectric photocatalytic performance of this sample was evaluated through the degradation of rhodamine B (RhB) and oxygen generation. Results indicated that the degradation rate of RhB reached 98.63 % within 25 min under the synergistic influence of light and ultrasound, which was 1.85 and 9.60 times higher than those of Bi2MoO6 and WO3, respectively. Furthermore, the optimal oxygen production efficiency was 167.41 µmol·g−1·h−1. This study provides a novel approach for designing more efficient piezoelectric photocatalysts.