Low-valence B-site cation substitution triggering polarization and oxygen vacancy enhancement for elevating piezocatalytic activity on Bi2MoO6

Piezocatalysis, as a rising star in catalysis, shows bright application prospects, but also has the issues of low catalytic efficiency, which is mainly derived from rapid charge recombination and insufficient catalytic reactive sites. In order to address the above two challenges, we select a layered perovskite Bi2MoO6 as the piezocatalyst model, and introduce the low-valence B-site cations I5+ and V5+ with similar ionic radius to substitute for Mo6+ in the MoO6 octahedra, which induce the distortion of MoO6 octahedra and introduction of more oxygen vacancies in Bi2MoO6 simultaneously. The replacement results in strengthened ferroelectric remanent polarization and piezoelectric properties, in which the piezoelectric coefficient of Bi2MoO6 increases to 1.69 and 1.36 times, respectively, when the optimal amounts of I5+ and V5+ is introduced into Bi2MoO6. At the same time, a higher concentration of oxygen vacancies is generated due to the charge compensation effect, which promotes the adsorption and activation of O2 on the surface of Bi2MoO6, and is conducive to the generation of reactive species. Benefiting from these advantages, the piezocatalytic performance for the degradation of various organic pollutants and antibiotics has been effectively heightened. This work illustrates the superiority and universality of nonequivalent cation substitution in improving piezocatalysis, and provides a reference for synergistic strategies to enhance piezocatalytic performance.