Abstract
Developing efficient solar-mechanical energy conversion systems is crucial for sustainable H(2)/H(2)O(2) production. We report an unprecedented piezoelectric metal-organic cage (MOC-FA3), integrated with piezoelectric β-ketoenamine COF (S-COF) into a Z-scheme heterojunction via supramolecular interactions. The non-centrosymmetric piezoelectricity of MOC-FA3 is confirmed by multimodal characterization (KPFM, piezoelectric coefficient measurement, and in situ spectroscopy) and piezocatalytic H(2)/H(2)O(2) production (334.3/203.6 µmol g(-1) h(-1)). Under ultrasound (60 W, 40 kHz) and AM 1.5G, the heterojunction achieves exceptional synergistic pure water splitting at 1297.6 H(2) and 1304.2 H(2)O(2) µmol g(-1) h(-1), among the highest for COF-based piezo-photocatalysts, with 1.95-fold and 2.06-fold enhancements over S-COF. This stems from Z-scheme charge transfer coupled with piezoelectric-field-enhanced separation. Experimental results and DFT calculations identify Pd sites (H(2) evolution) and C(2)-C(3) sites (2e(-) water oxidation → H(2)O(2)), with in situ EPR confirming •OH intermediates. This work introduces MOCs as a new piezoelectric material class, demonstrating synergistic Z-scheme/piezoelectric coupling for mechano-photonic energy conversion.