Revealing the flexoelectricity and flexocatalysis of BiOI nanoplates: new insight into the powerful catalytic material

Abstract

Flower-like BiOI nanoplates were successfully synthesized via a simple and eco-friendly chemical precipitation route and evaluated as flexocatalysts for the ultrasonic degradation of organic pollutants. The synthesized BiOI exhibited a well-defined layered structure with abundant crystal defects, including a high dislocation density and bismuth vacancies, together with a narrow band gap of 1.935(2) eV, which are favourable for catalytic activity. The material demonstrated an intrinsic flexoelectric coefficient of 12.00(8) pC/N, enabling efficient conversion of mechanical energy into electrical polarization under ultrasonic excitation. Consequently, the BiOI nanoplates exhibited outstanding flexocatalytic performance toward sonodegradation of Congo Red, achieving a degradation rate constant of 1.45 & times; 10-3 s-1. The enhanced catalytic activity is attributed to strain-gradient-induced flexoelectric polarization, which facilitates efficient charge separation and promotes the generation of reactive oxygen species. Comparative analysis further revealed that the catalytic performance of BiOI is comparable to or exceeds that of many reported metal oxide and metal oxide-based nanocatalysts. These findings establish flower-like BiOI nanoplates as an efficient and sustainable flexocatalyst and demonstrate the potential of exploiting flexoelectricity to develop mechanically driven catalytic systems for wastewater treatment and environmental remediation.