BiFeO₃ Nanoparticles: The "Holy-Grail" of Piezo-Photocatalysts?

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.