Humpback Whale‐Inspired High‐Sensitive Dual‐Piezoceramic Composite With Superior Force‒Electricity Conversion for Efficient Demulsification

ABSTRACT Piezoelectric catalysis is promising for safe and sustainable water purification, while achieving exceptional piezocatalytic efficiency is challenging due to huge energy consumption and the fatigue fracture risk of rigid piezoceramics. Here, a novel humpback whale‐inspired highly sensitive dual‐piezoceramic composite (BaTiO 3 /polydopamine‐modified porous spontaneously polarized ceramic, termed as BTO/PDA@PSPC) with superior force‒electricity conversion and underwater superoleophobicity is fabricated for efficient piezocatalytic in situ demulsification of oil‐in‐water (O/W) emulsion. The coordination of PDA and the modulation of PSPC induce oriented growth of BTO with edge nodule‐like structure to avoid fatigue fracture, and the interfacial charge/stress bridge of PDA and piezoelectric field (PEF) of PSPC endows BTO with astonishing piezoelectric activity. BTO/PDA@PSPC shows outstanding piezoelectric response, PEF of 1.46 × 10 9 V/m, and critical cavitation for generating e − ‒h + pairs to form reactive oxygen species (ROS). Superwetting BTO/PDA@PSPC triggered by ordinary stirring exhibits excellent piezocatalytic performance for complete demulsification of O/W emulsion within 15 min, outperforming contrastive catalysts by 3.3‒4.0 times. The electric field causes inhomogeneous polarization, dielectric coalescence, and demulsification of oil droplets successively, and the degradation of emulsifier by ROS prevents re‐emulsification of demulsified water. This strategy achieves sustainable and efficient demulsification via synergistic PEF and ROS, showing great promise in treating large‐scale oily wastewater.