In situ synthesis of p-n (BiO)4CO3(OH)2/Bi2O2CO3 internal polarized heterojunction for improved visible light photocatalytic performance

Abstract

P-n type (BiO)4CO3(OH)2/Bi2O2CO3 internal polarized heterojunction was prepared via an in situ photosynthesis method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM),UV-vis diffuse reflectance spectra (UV-vis DRS) and surface photovoltage (SPV). The results indicate that phase transition process of β-Bi2O3 → Bi2O2CO3 → (BiO)4CO3(OH)2 can be regulated by controlling the photosynthesis time. With increasing of reaction time, CO32- in Bi2O2CO3 structures is replaced by polar OH-, and the two-dimensional (2D) heterostructure of (BiO)4CO3(OH)2/Bi2O2CO3 is fabricated. The photocatalytic activities of the junction were investigated by degradation of tetrachlorophenol (4-CP) under the visible light illumination. The enhanced photocatalytic activity of (BiO)4CO3(OH)2/Bi2O2CO3 has been attributed to the synergetic effect between intrinsic internal electric field (IEF) and charge separation for a photocatalyst with p-n heterojunction structures. Moreover, h+ and •OH are proved working as the main active species for the degradation performence. It shows great potential in application for wastewater treatment.