Epitaxial-Growth SnSe₂/SnSe Lateral Heterojunction Boosts Piezocatalytic Degradation of Antibiotics

Piezoelectric materials provide new avenues for driving the catalytic degradation of organic pollutants by harvesting mechanical energy, but high carrier recombination is a major obstacle to improving piezoelectric catalytic efficiency. Heterojunction construction is one of the effective strategies used to inhibit carrier recombination. Especially, the lateral heterostructure can solve the problem of the decline in piezoelectric performance caused by vertical heterojunctions in two-dimensional materials. Here, a pioneering SnSe2/SnSe lateral heterojunction was fabricated by epitaxially growing SnSe2 along the edge of a SnSe nanosheet through a combination strategy of HNO3 exfoliation and calcination. Compared with SnSe, the SnSe2/SnSe heterojunction displayed much higher piezocatalytic activity for the degradation of various antibiotics in water. Based on the radical trapping experiments and electron paramagnetic resonance characterizations, superoxide radicals were identified as the dominant reactive oxygen species. The piezoelectric properties and electronic band structures of SnSe and SnSe2/SnSe were analyzed by piezoresponse force microscopy combined with density functional theory calculations. The enhancement mechanism of piezocatalytic performance of the SnSe2/SnSe heterojunction was elucidated, and a II-scheme charge transfer mechanism at the SnSe2/SnSe interface driven by a built-in electric field was put forward. This work will enrich the development of piezoelectric catalysis technology and provide new ideas for the design of heterostructured piezocatalysts.