Ultrahigh piezocatalytic capability in eco-friendly BaTiO₃ nanosheets promoted by 2D morphology engineering

Piezocatalysis, converting mechanical vibration into chemical energy, is an emerging technology to address environmental issues. In this work, we propose an efficient method to significantly improve the piezocatalytic activity by morphology engineering rather than composition design. The catalytic property in BaTiO₃ nanocrystallites with diverse morphologies is investigated by dye degradation and hydrogen production under ultrasonic vibration. The BaTiO₃ nanosheets exhibit an excellent piezocatalytic activity with a degradation rate of 0.1279 min^-1 for Rhodamine B, far beyond those in previous piezocatalytic literature and even comparable to excellent photocatalysts, and also a high hydrogen production rate of 92 μmol g^-1 h^-1. Compared with nanowires and nanoparticles, the 2D morphology greatly enhances the piezocatalytic activity in nanosheets owing to much larger piezoelectric potential. This proves that the piezocatalytic property is dominated by the morphology-dependent piezoelectricity, rather than specific surface area as other catalysis. Dominated by bending vibrating mode, the piezocatalytic activity reaches a maximum at the piezoelectric resonating frequency, and it increases with the ultrasonic power. Moreover, it has good reusability and wide versatility for catalytic degradation. This work gives an in-depth understanding of piezocatalytic mechanism and provides a way to develop high performance and eco-friendly piezocatalysts.