Strongly enhanced piezocatalysis of BiFeO3/ZnO heterostructure nanomaterials

Abstract

In this work, the construction of heterostructures is considered to be an outstanding method to enhance the decomposition ratio in the piezocatalysis process. Piezoelectric BiFeO₃/ZnO heterostructure nanomaterials synthesized via a mixing–calcining method exhibit an enhanced piezocatalysis performance through collecting vibration energy to decompose rhodamine B (RhB) dye. After undergoing 180 min vibration, with the different ZnO contents of 0 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt% and 5 wt%, the BiFeO₃/ZnO heterostructures can respectively decompose 73.4%, 87.0%, 96.9%, 92.9%, 67.9% and 55.1% RhB dye. The kinetic rate constant of the RhB dye decomposition is 21.0 × 10⁻³ min⁻¹ for the BiFeO₃/2%ZnO heterostructures, while it is only 7.37 × 10⁻³ min⁻¹ for the BiFeO₃. The reason for the enhanced piezocatalytic dye decomposition ratio may be that the heterostructure effectively separates the positive and negative charges to reduce the recombination of the positive and negative charges. These main medium active species such as hydroxyl radicals (˙OH) in the process of piezocatalysis are confirmed on the basis of the results of both electron spin resonance and active species capture experiments. The BiFeO₃/ZnO heterostructures, with a strongly enhanced piezocatalytic dye decomposition performance, offer a promising option to treat wastewater through collecting environmental vibration energy in the future.