Suppressing Charge Screening via Z-Scheme With Polarization Field for In Situ H₂O₂ Generation and Utilization.

Abstract

Piezoelectric polarization in n-type semiconductors provides a sustainable pathway for hydrogen peroxide (H₂O₂) production. However, its efficiency is fundamentally constrained by the piezoelectric screening effect, whereby accumulated free carriers rapidly neutralize polarization-induced charges, leading to short-lived internal fields and suppressed redox activity. Herein, ZnO nanoparticles are electrostatically integrated with a Zr-based metal-organic layer to construct a ZnO/Zr-MOL Z-scheme heterojunction that intrinsically mitigates this screening limitation. Interfacial coupling enables polarization-regulated band bending, spatially separating piezo-generated electrons and holes, and preventing their premature compensation by mobile carriers. The Z-scheme configuration preserves strong redox potentials while suppressing bulk and interfacial recombination, and the polarization-driven charge redistribution and dynamic realignment of the conduction and valence bands sustain the piezoelectric potential and markedly enhance carrier mobility and lifetime. Consequently, the optimized ZnO/Zr-MOL catalyst achieves an H₂O₂ production rate of 13.21 mm g^-1 h^-1 in pure water under ambient air conditions. When incorporated into an autonomous tidal-driven reactor, the heterostructure demonstrates strong environmental adaptability, achieving 74.5% degradation of Rhodamine B in 5 L of wastewater within 180 min. This study provides a fundamental strategy to overcome piezoelectric screening and establishes a mechanistic framework for polarization-assisted charge transfer in heterostructure systems.