The binary piezoelectric synergistic effect of KNbO3/MoS2 heterojunction for improving photocatalytic performance

Abstract

Piezoelectric polarization is a promising approach to promoting the separation and transfer of charge carriers of photocatalysts by modulating energy band structure. A binary piezoelectric integrated piezo-photocatalytic heterojunction o-KNbO3/MoS2 (o-KN/MS) is fabricated through few-layered MoS2 nanosheets growth on the ferroelectric orthorhombic KNbO3 (o-KNbO3). Under simultaneous light irradiation and ultrasonication, the optimal o-KN/MS exhibits a higher piezo-photocatalytic rhodamine B degradation rate (0.16979 min−1) than individual photocatalysis (0.00981 min−1) or individual piezocatalysis (0.09419 min−1). The piezo-photocatalytic degradation rates of RhB (0.16979 min−1), Cr (VI) (0.00877 min−1), and MB (0.01017 min−1) of o-KN/MS are 2.6, 7.9, and 4.2 times as large as that of single piezoelectric hybrid piezo-photocatalyst c-KNbO3/MoS2, respectively, where c-KNbO3 in c-KN/MS refers to non-piezoelectric paraelectric cubic KNbO3 (c-KNbO3). At the same condition, the current density for o-KN/MS reaches 54.96 μA/cm2, which is 2.9 folds as high as that of c-KN/MS. These results demonstrate that the altering piezoelectric polarization from the binary piezoelectric materials promotes continuous carrier separation within o-KNbO3 and MoS2 but also on the heterojunction interface, which provides a strategy for designing integrated piezo-photocatalyst to achieve efficient pollutant degradation and enhance electrochemical performance.