N-Doped Modified MoS2 for Piezoelectric–Photocatalytic Removal of Tetracycline: Simultaneous Improvement of Photocatalytic and Piezoelectric Properties

Piezoelectric and photocatalytic technologies use mechanical and light energy to decompose environmental contaminants, demonstrating a beneficial synergistic impact. This investigation employs a two-step hydrothermal-calcination technique to synthesize N-doped MoS2 photocatalytic materials. The ideal catalyst, N-MoS2-3, utilizing the synergistic effect of piezoelectric–photocatalysis processes, attained a TC degradation rate of 90.8% in 60 min. The kinetic constant (0.0374 min−1) is 1.75 times greater than the combined rates of single photocatalysis and piezoelectric catalysis, indicating a notable synergistic impact. The material has 80% degradation efficiency after five cycles, indicating its remarkable resilience. Mechanistic investigations reveal that nitrogen doping establishes an internal electric field by modulating the S-Mo-S charge distribution. Photogenerated electrons move to generate •O2−, while holes accumulate internally. The ultrasound-induced piezoelectric polarization field interacts with the photogenerated electric field in reverse, thereby synergistically improving carrier separation efficiency and facilitating redox processes. This study emphasizes the viability of non-metal doping as a method for modifying the properties of two-dimensional materials, offering a novel approach to enhance the synergistic attributes of piezoelectric and photocatalytic processes. This technology possesses significant promise for environmental restoration through the utilization of solar and mechanical energy.