Modulated covalent organic frameworks with higher specific surface area for the ultrasensitive detection of polybrominated biphenyls

•Series of COFs first modulated by DB with higher surface areas were constructed.•The structure-performance relationships of COFs were systematically investigated.•The DB-modulated COF coating featured outstanding enrichment performance for PBBs.•Ultrasensitive determinations of trace PBBs in real water samples were realized.