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

P-n type (BiO) 4 CO 3 (OH) 2 /Bi 2 O 2 CO 3 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 -Bi 2 O 3  → Bi 2 O 2 CO 3  → (BiO) 4 CO 3 (OH) 2 can be regulated by controlling the photosynthesis time. With increasing of reaction time, CO 3 2− in Bi 2 O 2 CO 3 structures is replaced by polar OH − , and the two-dimensional (2D) heterostructure of (BiO) 4 CO 3 (OH) 2 /Bi 2 O 2 CO 3 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) 4 CO 3 (OH) 2 /Bi 2 O 2 CO 3 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.