Piezocatalysis has gradually come into the limelight due to its great potential for solving energy shortages and environmental pollution problems. However, limited piezocatalytic efficiency is a severe bottleneck for its practical applications. Here, well-defined BaTiO 3 nanosheets with highly exposed {001} polar facets are successfully synthesized to enhance the piezocatalytic activity. The [001] piezoelectric polarization can drive the carriers to migrate to the surface along the out-of-plane direction. The polar surface provides abundant active sites for the piezocatalytic reaction. As a result, a superior piezocatalytic degradation ratio of organic pollutants is obtained with a high first-order rate constant k of 0.0835 min −1 , which is 2.7 times higher than the BaTiO 3 nanoparticles. Furthermore, BaTiO 3 nanosheets display an outstanding H 2 production capability, with the rate of 305 µmol g −1 h -1 , which is almost two times higher than that of BaTiO 3 nanoparticles. This work thus provides a novel and comprehensive strategy for designing high-performance piezocatalysts with an out-of-plane polarization, and also provides novel insights for the optimization of the piezocatalytic activity by regulating the polar facet of piezocatalysts.

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Poly‐L‐lactide (PLLA) offers a unique possibility for processing into biocompatible, biodegradable, and implantable piezoelectric structures. With such properties, PLLA has potential to be used as an advanced tool for mimicking biophysical processes that naturally occur during the self‐repair of wounds and damaged tissues, including electrostimulated regeneration. The piezoelectricity of PLLA strongly depends on the possibility of controlling its crystallinity and molecular orientation. Here, it is shown that modifying PLLA with a small amount (1 wt%) of crystalline filler particles with a high aspect ratio, which act as nucleating agents during drawing‐induced crystallization, promotes the formation of highly crystalline and oriented PLLA structures. This increases their piezoelectricity, and the filler‐modified PLLA films provide a 20‐fold larger voltage output than nonmodified PLLA during ultrasound (US)‐assisted activation. With 99% PLLA content, the ability of the films to produce reactive oxygen species (ROS) and increase the local temperature during interactions with US is shown to be very low. US‐assisted piezostimulation of adherent cells directly attach to their surface (such as skin keratinocytes), stimulate cytoskeleton formation, and as a result cells elongate and orient themselves in a specific direction that align with the direction of PLLA film drawing and PLLA dipole orientation.