Internal lattice stress–engineered piezopotential enhancement in polymeric CdS interparticle homojunctions for improved piezophotocatalytic activity

Piezopotential is considered one promising strategy to mitigate severe carrier recombination issue that affected in semiconductor photocatalysts. Herein, we employed a universal internal lattice stress engineering strategy to enhance the piezopotential in Zinc blende–wurtzite (Z-W) CdS systems. An interparticle homojunction structure with sphere, wire, and plate-like morphologies was designed via a novel cation exchange method. The catalytic activities were evaluated using methylene blue (MB) degradation as a model reaction under light irradiation, periodic ultrasonic irradiation, or both. Approximately 82 % MB degradation was achieved within 60 min and first order rate constant 0.0278 min⁻¹ by the plate-like Z-W CdS under piezophotocatalytic conditions, which was significantly higher than under either photocatalytic or piezocatalytic conditions alone. A first order rate constant 0.0220 min⁻¹ again outperforming its individual photocatalytic, piezocatalytic counterparts also mono phase catalyst. Supporting experiments, including piezoresponse force microscopy, piezocurrent measurements, impedance spectroscopy, and Mott–Schottky analysis, confirmed that the enhanced catalytic performance primarily stems from the stress-induced piezopotential formed at the interfaces. This piezopotential significantly improves the piezoelectric response, thereby strengthening the built-in electric field and facilitating more efficient electron–hole separation. This work broadens the application of interparticle homojunctions in piezophotocatalytic systems for sustainable water treatment and energy conversion application.