Tip effect and structural disordering in Bi2WO6 for enhanced piezo-photocatalytic nitrogen oxidation to nitric acid

Abstract

Piezo-photo coupling effect in charge separation has garnered substantial attention in recent research. However, the piezoelectricity-induced charges are inevitably depleted by the photoinduced current near the interface. Herein, we propose a meticulously designed conformity-directional dual electric field by introducing the tip effects and structural disordering in Bi2WO6. In the absence of cocatalysts, Bi and O vacancies rich Bi2WO6 with a Bi0 cluster (Bi0/Bi2−xWO6−x, BBW) exhibited remarkable piezo-photocatalytic nitrogen oxidation to nitric acid rates (5.26 mg g−1 h−1), which is 5 times that of pure Bi2WO6. Theoretical and experimental results demonstrated that the cluster and vacancies acted as the major strain and potential center, which can be referred to as the “tip effect” and structural disordering that enhanced the piezoelectric-polarization electric field and the photoinduced built-in electric field along the same direction to promote charge transfer and exciton dissociation. Moreover, the cluster and vacancies acted as activation sites for O2 and N2, reducing the surface reaction barrier. Thus, the proposed method will aid in designing dual-polarization electric fields for enhancing carrier separation.