Self-Assembled LaFeO₃/ZnFe₂O₄/La₂O₃ Ultracompact Hybrids with Enhanced Piezo-Phototronic Effect for Oxygen Activation in Ambient Conditions

Piezoelectric polarization portrays a promising technology to regulate the photogenerated charge carrier separation and transfer behaviors, and the design of multifunctional catalysts with piezo-phototronic effect is a key step. One strategy is to prepare a composite catalyst combining the ideal properties from each individual component. Herein, a facial dopant-induced self-assembling strategy is reported to fabricate an ultracompact nanocomposite (LaFeO₃/ZnFe₂O₄/La₂O₃) with enhanced efficiency for piezo-photocatalysis. The composite is synthesized at 800 °C from the one-pot method, thus the self-constructed interface is created during multi-phase formation, providing the intimate grain-to-grain contact between the semiconductive LaFeO₃ and piezoelectric ZnFe₂O₄/La₂O₃ phases. In such a composite, a synergistic effect for oxygen activation is realized via the effective manipulation of the photogenerated charge carrier separation and spatial transportation through the vibration-created piezopotential. A high piezoelectric coefficient (d₃₃) up to 826 pm V⁻¹ and a superior H₂O₂ yield of 403 µmol g⁻¹ h⁻¹ (in open air and pure water) are achieved on the optimized composite, outperforming most of the reported lead-free piezo-photocatalyst. The ultracompact composite is very robust without any decay in H₂O₂-delivering capability after many cyclic tests. This study provides a universal strategy for the rational design of high-performance piezo-photocatalysts.