Engineered Composite Interfacial Electric Field Boosts Piezocatalysis of Perovskite Ferroelectrics

Reducing the level of annihilation of electrons and holes is considered to be a feasible strategy to promote piezocatalytic activities. But this strategy is only achieved through cumbersome sample preparation technologies, hindering its practical applications. Herein, we introduce a simple and efficient technique, the conventional solid-state method, to engineer a composite interfacial electric field to solve this problem, and validate it in a composite piezocatalysis composed of potassium sodium niobate ((K, Na)NbO₃, KNN) and multiwalled carbon nanotubes (MWCNTs). The KNN-1CNT sample, a piezocatalyst doped with 1 wt % MWCNTs, shows a degradation rate (k) of 127 × 10^-3 min^-1 for Rhodamine B (RhB) dye and a hydrogen peroxide (H₂O₂) production rate of 36 μmol/h, about 27 times more than a reported ferroelectric composite piezocatalyst. The excellent piezocatalytic activities are attributed to the good crystallinity, slightly increased oxygen vacancies, and especially the optimal composite interface electric field. Therefore, our proposed method provides a paradigm for obtaining large-scale perovskite piezocatalysts with high piezocatalytic activities.