Polar piezoelectric potential energy driving interfacial charge for high-performance photoelectrochemical sensing

A “Polar Piezoelectric Potential Energy Driving Interfacial Charge” strategy is proposed to address the low carrier mobility in heterojunction-based PEC sensors. • Light-induced strain activates the piezoelectric polarization field of BaTiO 3 interlayer, providing a sustained Coulombic driving force for carrier separation. • BaTiO 3 interlayer regulates the energy band alignment and enhances the polarization effect in the p-n heterojunction. • The sensor achieves OTA detection with a wide linear range (1.00 × 10 −5 –10.0 ng/mL) and a low detection limit (3.93 fg/mL). Heterojunction photoelectrodes can effectively enhance the performance of photoelectrochemical (PEC) sensors. Nevertheless, addressing the structural limitations of heterojunction photoelectrodes to achieve fast and stable carrier migration while suppressing electron-hole pair (EHP) recombination remains a huge challenge. In this paper, we propose a “polar piezoelectric potential energy driving interface charge” strategy to design a highly sensitive PEC sensing platform for sensitively detection of ochratoxin A (OTA). This strategy is defined as the use of piezoelectric polarization-induced internal electric field to provide a sustained Coulombic driving force for interfacial charge carrier migration. The platform is constructed by integrating BaTiO₃-induced polar p-n heterojunction CoCdS/Ag₂O as a photoanode. Due to the inherent piezoelectric properties of BaTiO 3 , it can serve as an embedding layer of p-n heterojunction. Under the built-in potential of the p-n heterojunction, the two sides of BaTiO 3 generate a piezoelectric polarization charges, establishing a strong piezoelectric polarization field. This field induces the rearrangement of electrons and holes, providing a sustained and stable Coulombic driving force for the migration of charge carriers, which facilitates the rapid separation and transfer of photogenerated charge carriers. Based on this strategy, the PEC sensor exhibits a detection range of 1.00 × 10 −5 to 10.0 ng/mL as well as a minimum detection limit of 3.93 × 10 −6  ng/mL for OTA. It demonstrates excellent stability, anti-interference and reproducibility, with feasibility for real sample detection. This platform offers new opportunity for sensitive detection of trace mycotoxins in food with piezoelectric effect modulated PEC sensors. Download: Download high-res image (129KB) Download: Download full-size image