2D/2D KNbO3/MoS2 heterojunctions for piezocatalysis: Insights into interfacial electric-fields and reactive oxygen species

Developing and designing an excellent environmental cleanup piezocatalyst remains a considerable challenge for realizing a highly effective conversion of mechanical vibration energy into the chemical activity. Herein, the 2D/ 2D heterojunctions of ferro-/piezoelectric KNbO3/MoS2 nanosheets were rationally designed and constructed to satisfy this goal. Under ultrasonic vibration, the 2D/2D KNbO3/MoS2 heterojunction could simultaneously remove tetracycline hydrochloride (TC) and Rhodamine B (RhB). After 30 min of piezocatalysis, the reaction rate constants (k) were 0.085 min-1 and 0.092 min-1 for TC and RhB, which were near 17.0 and 6.1 times higher than that of pristine KNbO3, respectively. Additionally, the antibacterial properties of the 2D/2D heterojunction reached more than 99.77% against Escherichia coli and 60.03% against Staphylococcus aureus within 10 min ultrasound treatment, respectively. The strong piezocatalytic activity was attributed to: (1) the polarizationmodulated interfacial electric-fields were realized through the desirable ferro-/piezoelectric 2D/2D nanostructures, (2) intimate and large interfaces were constructed between KNbO3 and MoS2 nanosheets, which created unique opportunities for facilitating free charges transfer, (3) KNbO3/MoS2 heterojunctions represented two reactive oxygen species of center dot O2- and center dot OH were greatly enhanced in contrast to bare KNbO3 and MoS2, supporting the observation of efficiently piezocatalytic activity. Overall, this research illustrates the effect of a wonderful and stable catalyst for environmental remediation and brings new inspirations for engineers to develop high-efficiency piezocatalysis for multifunctional environmental applications.