Highly efficient synergetic piezo/photocatalytic degradation in novel M0.5Bi2.5Nb2O9 (M=Li, Na, K) ferroelectric nanosheets

Inhibiting the recombination of photo-generated charge carriers remains one of the important challenges for photocatalytic materials nowadays. For this, we reported a series of novel bismuth layered structure ferroelectrics: M0.5Bi2.5Nb2O9 (M = Li, Na, K) nanosheets prepared by one-step hydrothermal method. The fabricated nanosheets with average thickness size of about 32 nm (Li0.5Bi2.5Nb2O9), 45 nm (Na0.5Bi2.5Nb2O9), 108 nm (K0.5Bi2.5Nb2O9) possess excellent photodegradation performance to various organic dye pollutants with high concentration of 20 mg/L [Rhodamine B (RhB), methyl orange (MO) etc.]. Interestingly, the degradation rate constants of RhB and MO can be further improved by polarization-induced charge separation under ultrasonic-assisted illumination condition, compared with those of light illumination alone, and increased by about 2.5 times for Na0.5Bi2.5Nb2O9 nanosheets. These findings make bismuth layered ferroelectric materials have a potential application in wastewater treatment as a kind of important photocatalysis.