Enhanced visible light responsive piezoelectric photocatalysis based on (Na, K)NbO3 nanostructures for effective organic pollutant degradation

Abstract

Incorporation of the piezoelectric effect into photocatalysis provides a built-in polarization field and has the potential to effectively separate the photo-generated electron-hole pairs, which can greatly enhance the degradation performance of the organic pollutants. For this reason, the search for lead-free ferroelectric materials that can combine photocatalytic and piezocatalytic capabilities is highly demanded. In this work, a series of (Na, K)NbO₃ with various Na⁺/K⁺ ratios were fabricated by a simple hydrothermal method. When the NaOH to KOH ratio was 50/50, the Na_0.5K_0.5NbO₃ nanostructure displayed morphotropic phase boundary separating orthorhombic and monoclinic phases. Under the co-excitation of ultrasonic vibration and visible light irradiation, the Na_0.5K_0.5NbO₃ sample exhibited an excellent ability for the degradation of Eosin Yellow (EY) dye, which can degrade the dye completely within 5 h, which was 3.67 times and 1.52 times faster than that of piezocatalysis under ultrasonication and photocatalysis under light illumination alone. These findings offer promising implications for the advancement of piezo-photocatalysts that employ tiny mechanical vibrations and visible light irradiation to efficiently degrade organic contaminants.