Enhanced Piezocatalytic Activity of Sr0.5Ba0.5Nb₂O₆ Nanostructures by Engineering Surface Oxygen Vacancies and Self-Generated Heterojunctions

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 0.5 Ba 0.5 Nb 2 O 6 nanorods fabricated by a molten salt synthesis method. The as-fabricated Sr 0.5 Ba 0.5 Nb 2 O 6 /Sr 2 Nb 2 O 7 nanocomposites with controllable oxygen vacancies exhibited excellent piezocatalytic activity under ultrasonic vibration, with an about 7 times enhancement of the rate constant ( k = 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 (H 2 annealed at 500 °C) compared to pristine Sr 0.5 Ba 0.5 Nb 2 O 6 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.