Figure 2. (A) XPS survey spectrum and (B) O 1s, (C) C 1s, (D) Fe 2p, (E) Ti 2p, and (F) Cu 2p high-resolution spectra for CuFeO2–MX. XPS: X-ray photoelectron spectroscopy; CuFeO2–MX: CuFeO2–MXene.