Polarization Boosted Solar H2O2 Production over Quantum Dot-Decorated Nanosheets with Rich Oxygen Vacancies

Field-assisted photocatalytic H2O2 production using piezoelectric semiconductors is a promising approach for sustainable energy conversion and storage. Herein, to bridge the intrinsic properties of these semiconductors and the external field effects toward enhanced photocatalytic performance, a two-dimensional Bi2WO6 nanosheet with good flexibility and piezoelectricity is used as a building block to construct heterojunctions with BiVO4 quantum dots. Subsequent decoration by BiVO4 not only improves the visible-light response but also chemically increases the structural asymmetry, resulting in an enhanced piezoelectric effect. Under an ultrasound-irradiation-induced mechanical stress field, the coupling effect of flexoelectric and piezoelectric polarization over the BiVO4/Bi2WO6 heterojunction facilitates the separation and migration of photogenerated electrons and holes. Meanwhile, the electron trapping states induced by oxygen vacancies inhibit the direct recombination of photogenerated carriers, which further improves the photocatalytic performance of this noble-metal-free system with a H2O2 production rate of up to 4.86 mmol g–1 h–1. This study sheds light on the rational design of field-assisted photocatalytic systems with engineered local catalyst–support interactions, taking advantage of coupled polarization effects.