Nanocomposites of NaNbO ₃ Nanorods and Mo ₂ AlB ₂ on Porous PVDF Foam as a Tribo–Piezo Catalyst for Rapid Degradation of Organic Dyes

Industrial waste containing synthetic dyes poses serious environmental problems, because these materials are difficult to break down and are chemically stable, leading to water pollution. Hence, it is crucial to develop ecofriendly and effective techniques for their removal. In this work, a PVDF-NaNbO3-Mo2AlB2-based porous, flexible foam is synthesized as a catalyst using the solution casting method for the efficient removal of dyes. NaNbO3 was prepared via a hydrothermal route, while Mo2AlB2 was obtained through high-temperature annealing. SEM analysis confirms the formation of a highly porous structure in the PVDF-based nanocomposite foam, while XRD results verify the successful formation and phase integration of the PVDF-NaNbO3-Mo2AlB2 nanocomposite. The porous structure of the foam increases the active surface area, facilitating an efficient interaction with dye molecules. The synthesized foam utilizes tribo-induced piezocatalysis, where mechanical energy is converted to electrochemical potential through the combined effects of triboelectricity and piezoelectricity. The flexible PVDF matrix contributes triboelectric activity, NaNbO3 provides a strong piezoelectric response, and Mo2AlB2 enhances charge transfer between the interfaces. The detailed structural characterizations revealed that the synthesized foam possesses a highly porous structure with a large surface area, confirming its well-developed morphology and composition. Under the effect of vortex-induced mechanical stress, the foam demonstrates notable catalytic activity, achieving degradation efficiency of 97% for Rhodamine B and 98% for Methylene Blue within 60 min, without any external light source or chemical oxidants. The catalyst shows good stability and reusability, maintaining a degradation efficiency of 90% even after five successive cycles. Furthermore, scavenger tests reveal that superoxide radicals (•O2–) play the dominant role, while holes and hydroxyl radicals contribute to a lesser extent. In the future, such tribo-induced piezo systems can be further studied for large-scale environmental remediation and energy–environment coupling applications.