Flexible 3D KNN piezocatalytic porous foam for highly efficient degradation of aqueous organics

Piezocatalysis is a physical/chemical process that utilizes piezoelectric potential to drive chemical reactions, harnessing ubiquitous mechanical energies from the nature for various catalysis applications. Despite the high efficiency of piezocatalytic powders, the particles tend to disperse in aqueous systems and are difficult to separate, which poses a risk of secondary pollution. Herein, a flexible piezocatalytic foam is designed and fabricated, which is composed of potassium sodium niobate (KNN) piezoelectric powders embedded in the PDMS scaffold. The as-prepared KNN-PDMS composite foam demonstrates excellent piezocatalytic efficiency for organic pollutant removal among state-of-the-art integral piezocatalytic platforms, which lie in the synergy of proper piezoelectric materials and abundant interconnected pores within the flexible foam. In addition, as a monolithic platform, KNN-PDMS foam is easy to be collected, with high recycle stability and applicability for treating various pollutants, resulting in dominant advantages over powder-based systems for practical high-flux wastewater treatment. Significantly, the optimized 1.5KNN-PDMS sample achieved a RhB degradation rate constant of 34.71×10 -3 min -1 , with only a 7.5% decrease in activity after four consecutive cycles, and the KNN-PDMS foam maintained excellent selectivity toward RhB. This work not only mitigates the problem of secondary pollution but also provides a practical and efficient strategy for the stable degradation of organic pollutants in real aqueous environments.