Figure 6

XPS testing of material: (a) XPS spectra of Cr 2P after adsorption of NMC-2, (b) XPS spectra of Fe 2P before adsorption of NMC-2, (c) XPS spectra of Fe 2P adsorbed by NMC-2, (d) XPS spectra of N 1s before adsorption of NMC-2, (e) XPS spectra of N 1s after adsorption of NMC-2, (f) full spectrum of NMC-2 before and after adsorption.