Recently, piezoelectric‐based catalysis has been demonstrated to be an efficient means and promising alternative to sunlight‐driven photocatalysis, where mechanical vibrations trigger redox reactions. Here, 60 nm‐size BiFeO3 nanoparticles are shown to be very effective for piezo‐degrading Rhodamine B (RhB) model dye with record degradation rate reaching 13 810 L mol−1 min−1, and even 41 750 L mol−1 min−1 (i.e., 100% RhB degradation within 5 min) when piezocatalysis is synergistically combined with sunlight photocatalysis. These BiFeO3 piezocatalytic nanoparticles are also demonstrated to be versatile toward several dyes and pharmaceutical pollutants, with over 80% piezo‐decomposition within 120 min. The maintained high piezoelectric coefficient combined with low dielectric constant, high‐elastic modulus, and the nanosized shape make these BiFeO3 nanoparticles extremely efficient piezocatalysts. To avoid subsequent secondary pollution and enable their reusability, the BiFeO3 nanoparticles are further embedded in a polymer P(VDF‐TrFE) matrix. The as‐designed flexible, chemically stable, and recyclable nanocomposites still keep remarkable piezocatalytic and piezo‐photocatalytic performances (i.e., 92% and 100% RhB degradation, respectively, within 20 min). This work opens a new research avenue for BiFeO3 that is the model multiferroic and offers a new platform for water cleaning, as well as other applications such as water splitting, CO2 reduction, or surface purification.

Organic ferroelectrics are increasingly important due to their complementary properties to classical, inorganic ferroelectrics. Flexibility, chemical resistance, scalability, high breakdown fields, and biocompatibility are attractive for many applications like energy harvesting and storage. The most known energy harvesting methods are piezoelectric, pyroelectric, and triboelectric. Here, we apply the well-established material's figures of merit to five polyvinylidenefluoride-based compositions ranging from ferroelectric to relaxor-like behavior to emphasize the importance of several key material parameters contributing to the maximal power output of energy harvesting devices. Afterward, we discuss the possibility of the same functional material storing the output energy for the development of scalable multifunctional devices.