Sustainable piezo-photocatalysis of magnetoelectric Bi₂WO₆/CoFe₂O₄ composites with coherent interfaces

Magnetoelectric composites composed of piezoelectric and magnetic phases with catalytic performance hold great promise for recyclable piezo-photocatalysis applications. However, interfaces in conventional composites are structurally incoherent due to large lattice mismatches coupled with low bond strength restricting catalytic activity and cycling stability. Herein, magnetoelectric Bi₂WO₆/CoFe₂O₄ composites with atomic-level matched coherent interfaces are prepared by a simple two-step calcination based on heterogeneous nucleation. The coherent interface effectively improves the composite electric field and strengthens interface bonding. The stress induced by coherent interfaces increases the distortion of [WO₆] octahedra in Bi₂WO₆ thereby increasing spontaneous polarization and the internal electric field. Moreover, interfacial coherency provides a carrier transmission channel that significantly reduces charge transfer resistance caused by lattice mismatch thereby improving the interface electric field. Bi₂WO₆/Co₂Fe₂O₄ samples with coherent interfaces offer superior stability for catalytic decomposition of Rhodamine B with 90 % retention of activity over 12 cycles under visible-light irradiation with ultrasonic excitation. These results are much superior to samples without coherent interfaces. Our study proposes a novel structure for sustainable composite catalysts expanding the utility of coherent interfaces in multifunctional composite systems.