Piezoelectric-Enhanced Photocatalytic Performance of BaTi₂O₅ Nanorods for Degradation of Organic Pollutants

The combination of the piezoelectric effect and photoexcitation properties in ferroelectric/piezoelectric materials used for piezo-photocatalysis is one of the current research hotspots in the field of sewage treatment and environmental remediation. Lead-free ferroelectric BaTi2O5 (BT2) exhibits a strong photoexcitation response and is strongly piezoelectric, so it shows excellent promise as an effective piezo-photocatalyst. Herein, a molten salt method was adopted to prepare a 1D BT2 nanorod with different average aspect ratios, which have been used as piezo-photocatalysts for the first time. The as-prepared BT2 nanorods had an excellent piezoelectric response, as determined by piezo-response force microscopy. The optimal BT2 nanorods were able to piezo-photocatalytically degrade rhodamine B (RhB) with excellent performance. Under ultrasonication and visible-light coexcitation, this catalyst achieved the highest first-order rate constant of k = 0.0353 min(-1), 4.24 times higher than the rate constant achieved with ultrasonic excitation alone and 5.42 times higher than that achieved under visible-light irradiation alone. Moreover, the best degradation effect for the removal of quinolones [levofloxacin (LEV)] and other organic pollutants (methylene blue and methyl orange) was also achieved by the BT2 nanorods under ultrasonication and visible-light coexcitation. The internal piezoelectric field caused by bending vibration deflected the photogenerated carriers to the radial direction, which originally flowed toward the ends of the nanorods. This increased the participation of carriers at the active sites and reduced their migration distance. Therefore, the recombination of photogenerated carriers was inhibited, and better piezo-photocatalytic performance for pollutant degradation was achieved. The strong correlation between piezoelectric properties and the coupling effect of piezoelectric-photocatalysis is demonstrated by this work, which offers a strategy to optimize the flow of photogenerated charge carriers in one-dimensional (1D) photocatalysts and, in turn, improve the photocatalytic efficiency of 1D photocatalysts for the degradation of organic pollutants.