Coupling of piezocatalysis and photocatalysis for efficient degradation of methylene blue by Bi0.9Gd0.07La0.03FeO3 nanotubes

Photocatalytic degradation of organic pollutants is of great significance for wastewater remediation but is still hindered by the poor catalytic efficiency of the catalysts. Herein, we report a strategy to simultaneously introduce piezocatalysis and to enhance the intrinsic photocatalysis in a single catalyst, which improved the performance for catalytic degradation of methylene blue (MB) significantly. Specifically, piezoelectric BiFeO 3 (BFO) nanotube doped with different contents of Gd and La (Bi 0.9 (Gd x La 1− x ) 0.1 FeO 3 ) were produced by electrospinning. The doping led to a higher concentration of surface oxygen vacancy (OV) in Bi 0.9 Gd 0.07 La 0.03 FeO 3 , which effectively increased the piezoelectric field due to the deformation of BFO, and suppressed the recombination of photon-generated electron-hole pairs. The Bi 0.9 Gd 0.07 La 0.03 FeO 3 nanotube showed excellent catalytic performance under simultaneous light irradiation and ultrasonic excitation, giving an extraordinary 95% degradation of MB within 90 min. These findings suggest that the piezoelectric effect combined with defect engineering can enhance the catalytic performance of Bi 0.9 Gd 0.07 La 0.03 FeO 3 nanotube. This could potentially be extended to other catalytic systems for high-performance pollutant treatment.