Enhanced Piezocatalytic Activity of Sr_0.5Ba_0.5Nb₂O₆ Nanostructures by Engineering Surface Oxygen Vacancies and Self-Generated Heterojunctions

Abstract

Piezocatalysis provides a promising strategy for directly converting weak mechanical energy into chemical energy. In this work, we report a simple one-step hydrogen reduction route for the simultaneous generation of surface defects and heterojunctions in Sr_0.5Ba_0.5Nb₂O₆ nanorods fabricated by a molten salt synthesis method. The as-fabricated Sr_0.5Ba_0.5Nb₂O₆/Sr₂Nb₂O₇ nanocomposites with controllable oxygen vacancies exhibited excellent piezocatalytic activity under ultrasonic vibration, with an about 7 times enhancement of the rate constant (<i>k</i> = 0.0395 min^-1) for rhodamine B degradation and an about 10 times enhancement of the water-splitting efficiency for hydrogen generation (109.4 μmol g^-1 h^-1) for the optimized sample (H₂ annealed at 500 °C) compared to pristine Sr_0.5Ba_0.5Nb₂O₆ nanorods. This work demonstrates the essential role of a well-modulated oxygen vacancy concentration in the piezocatalytic activity and provides an inspiring guide for designing self-generated heterojunction piezocatalysts.