In situ preparation of novel p-n junction photocatalyst BiOI/(BiO)2CO3 with enhanced visible light photocatalytic activity

► BiOI/(BiO)2CO3 was synthesized using an in situ hydroiodic acid etching way. ► BiOI/(BiO)2CO3 displayed excellent photocatalytic activity under visible light. ► O2− and h+ played the major roles for MO degradation over BiOI/(BiO)2CO3. ► p-BiOI/n-(BiO)2CO3 junction significantly affected MO degradation.