In situ synthesis of Cl-doped Bi2O2CO3 and its enhancement of photocatalytic activity by inducing generation of oxygen vacancies

In this paper, a novel ionic liquid-assisted solvothermal method to prepare Cl-doped bismuth oxycarbonate (Bi2O2CO3) is presented. The ionic liquid of [Hnmp]Cl not only enhances the solvothermal process to help the formation of Bi2O2CO3, but also provides chloride element as a dopant. XRD and XPS show that all three samples are Bi2O2CO3 with high purity. XPS, solid EPR, and TEM results prove that Cl is doped into the Bi2O2CO3 lattice and oxygen vacancies are generated. DRS results show that after Cl doping, the absorption of visible light by Bi2O2CO3 is enhanced. Surface photovoltage (SPV) and transient photocurrent tests show that as the doping amount of Cl increases, the separation efficiency of photogenerated electron–hole pairs over Bi2O2CO3 improves. The photocatalytic activity of Bi2O2CO3 is evaluated by the degradation of rhodamine B, which is increased after Cl doping. This work would broaden the application of ionic liquids in the solvothermal process and deepen the understanding of anionic ion doping in Bi2O2CO3.