Tandem Fields Facilitating Directional Carrier Migration in Van der Waals Heterojunction for Efficient Overall Piezo‐Synthesis of H2O2

Abstract Piezo‐synthesis of H 2 O 2 utilizing sustainable mechanical energy as well as earth‐abundant water and oxygen is a green, cost‐effective, and promising approach. However, achieving simultaneous two‐electron water oxidation reaction (2e − WOR) and two‐electron oxygen reduction reaction (2e − ORR) faces huge challenges due to insufficient synergistic active sites and slow/messy carrier transfer. Herein, a novel 2D/2D van der Waals heterojunction consisting of BiOIO 3 and carbon nitride (BIO/CN) is elaborately designed for highly efficient overall H 2 O 2 piezo‐synthesis. Theoretical/experimental results reveal that a Z‐scheme electron transfer is formed and facilitated by the tandem interfacial electric field and the bulk piezo‐polarization field. On this basis, the carriers are efficiently separated while the oxidation/reduction capacity is preserved, thus providing the strong driving force for the 2e − WOR and 2e − ORR on BIO and CN, respectively. Furthermore, the kinetic and thermodynamic processes of WOR and ORR for H 2 O 2 synthesis improve remarkably. Therefore, BIO/CN exhibits an excellent H 2 O 2 yield of 259.8 µM within 30 min in pure water and air atmosphere (without any sacrificial agents and aeration). This study provides a new idea on strategically controlling electron transfer toward high‐efficiency H 2 O 2 piezo‐synthesis and expands the avenue for developing effective environmental purification materials.