Fig. 2: XPS characterization of 6FDA-TFDB-x precursor and CMS.

a Typical F1s XPS of 6FDA-TFDB-x precursors to compare with AlF₃. b C1s XPS of 6FDA-TFDB-x precursors. c F1s of 6FDA-TFDB-x CMS membranes with AlF₃. d N1s of 6FDA-TFDB-x CMS membranes with 6FDA-TFDB precursor.