Complementary conjugated piezo-phototronic polarized blue TiO2 - KNN for piezophotocatalytic degradation of tetracycline enhanced under gentle oscillatory hydrodynamic disturbances

Recently, tetracycline (TC) is classified as an emerging contaminant due to its rapid discharge into the environment from anthropogenic sources. Piezophotocatalysis offers a unique solution to degrade TCs by collaboratively harnessing both solar and hydro energy. However, practical applications have been hampered by the necessitation of high energy requirement ultrasonic baths. In this work, BT-KNN conjugates were investigated for piezophotocatalytic TC degradation. Under agitation conditions, characterization studies demonstrated an amplified photocurrent, diminished charge transfer resistance and reduced radiative recombination. Concomitantly, BT-KNN composites exhibit enhanced TC degradation and apparent rate constant with increased fluid disturbance frequencies, illustrating 91.3% degradation in 3 h under gentle 4 Hz oscillations. These hydrodynamic disturbances engender a propitious piezopolarization which modulated the junction band bending and ameliorated the interfacial charge transfer, intensifying its performance. Optimization studies further illustrates the tradeoff dynamics between high photoactivity of BT and high piezo-enhancement of KNN.