Solar-mechanical H₂O₂ production powered by defect dipole polarization in a nonpolar semiconductor

Piezo-photocatalytic H₂O₂ production faces a central challenge: inadequate visible-light absorption and insufficient driving forces for charge separation, especially in wide-bandgap nonpolar semiconductors. To address this, we propose a strategy that constructs Cu⁺-oxygen vacancy defect dipoles within nonpolar ZrO₂ to enable piezo-photo coupling. Under ultrasonic excitation, these defect dipoles produce a robust piezoelectric polarization field that facilitates directional separation of photogenerated carriers. As a result, charge recombination at visible-light-absorbing defect states is effectively suppressed, enabling synergistic utilization of mechanical and optical energy. The optimized catalyst exhibits a remarkable H₂O₂ production rate of 415.36 μmol·g^-1·hour^-1 under ambient air/water conditions and achieves near-complete degradation (88.7%) of rhodamine B in continuous-flow wastewater treatment (1 liter within 60 min). Theoretical calculations further reveal that the defect dipoles lower the d-band center of the active sites, thereby promoting *OH desorption and accelerating H₂O₂ formation kinetics. This study offers a viable strategy for inducing piezoelectricity in nonpolar semiconductors, thereby establishing design principles for high-performance piezo-photocatalytic systems.