Enhanced Generation of Reactive Oxygen Species via Piezoelectrics based on p–n Heterojunctions with Built-In Electric Field

Abstract

Tuning the charge transfer processes through a built-in electric field is an effective way to accelerate the dynamics of electro-and photocatalytic reactions. However, the coupling of the built-in electric field of p−n heterojunctions and the microstrain-induced polarization on the impact of piezocatalysis has not been fully explored. Herein, we demonstrate the role of the built-in electric field of p-type BiOI/n-type BiVO 4 heterojunctions in enhancing their piezocatalytic behaviors. The highly crystalline p−n heterojunction is synthesized by using a coprecipitation method under ambient aqueous conditions. Under ultrasonic irradiation in water exposed to air, the p−n heterojunctions exhibit significantly higher production rates of reactive species (•OH, •O 2 − , and 1 O 2 ) as compared to isolated BiVO 4 and BiOI. Also, the piezocatalytic rate of H 2 O 2 production with the BiOI/BiVO 4 heterojunction reaches 480 μmol g −1 h −1 , which is 1.6-and 12-fold higher than those of BiVO 4 and BiOI, respectively. Furthermore, the p−n heterojunction maintains a highly stable H 2 O 2 production rate under ultrasonic irradiation for up to 5 h. The results from the experiments and equation-driven simulations of the strain and piezoelectric potential distributions indicate that the piezocatalytic reactivity of the p−n heterojunction resulted from the polarization intensity induced by periodic ultrasound, which is enhanced by the built-in electric field of the p−n heterojunctions. This study provides new insights into the design of piezocatalysts and opens up new prospects for applications in medicine, environmental remediation, and sonochemical sensors.