Enhanced Lattice Polarization and Directed Charge Transport Toward Pt Surface Sites Accelerate the Volmer Step in Piezocatalytic H₂ Evolution on Co-Doped BiFeO₃

Piezocatalysts utilize mechanical stimulation to generate piezoelectric polarization for hydrogen evolution; however, the effective translation of polarization-induced charges into surface reaction kinetics remains a key limitation, particularly for the rate-determining Volmer water dissociation step. Here, we report a Co-doped BiFeO₃ piezocatalyst (BCFO) modified with platinum surface sites (Pt/BCFO), in which lattice polarization enhancement and surface reaction kinetics are regulated through distinct yet complementary roles. Co doping induces lattice distortion that enhances piezoelectric polarization, promoting directional charge transport and increasing surface charge availability. Pt sites facilitate water dissociation, thereby accelerating the Volmer step without altering the lattice polarization behavior. Piezoresponse force microscopy, photoluminescence, and electrochemical analyses confirm enhanced polarization-induced charge separation and transport, while density functional theory calculations reveal a substantially reduced water dissociation barrier on Pt sites. As a result, the Pt/BCFO catalyst achieves a piezocatalytic hydrogen evolution rate of 1896.4 µmol g⁻¹ h⁻¹, corresponding to a 16-fold enhancement compared to pristine BiFeO₃. Furthermore, composite films incorporating the catalyst into a poly(vinylidene fluoride) matrix demonstrate effective mechanical energy harvesting and convenient catalyst recovery. This work establishes a direct mechanistic link between lattice polarization and surface reaction kinetics for accelerating the Volmer step in piezocatalytic hydrogen evolution. © 2026 Wiley-VCH GmbH.