Two layered Bi-based borate photocatalysts MBi2B2O7 (M = Ca, Sr) for photocatalytic degradation and oxygen activation

Abstract

Layered bismuth-based photocatalytic materials have great potential for environmental purification. In this work, we developed two novel layered bismuth-based borate photocatalysts CaBi2B2O7 (CBBO) and SrBi2B2O7 (SBBO) via solid-phase reaction. The crystal structure, microstructure and optical properties were investigated. The photocatalytic activities were studied by decomposition of tetracycline hydrochloride (TH) and evolution of reactive oxygen species (ROS) under UV light irradiation. The results revealed that CBBO and SBBO exhibit benign TH degradation activity with certain mineralization abilities. Within 4 min illumination, almost 70% and 58% of tetracycline hydrochloride was degraded by CBBO and SBBO, respectively. The quantitative capture experiment of radicals showed that the production rate of OH and O2− was determined to be 1.27 × 10-7 and 10.98 × 10-7 mol·L-1 min-1 for CBBO and 1.01 × 10-7 and 11.75 × 10-7 mol·L-1 min-1 for SBBO, respectively. Density functional theory (DFT) calculation results demonstrated that CBBO has smaller effective masses of electrons and holes than SBBO, which results in higher charge separation efficiency and photocatalytic activity. This work provides two new layered bismuth-based borate photocatalysts for photocatalytic environmental applications.