Peak (eV)

Assignment

Surface group

Reference

O1s

532.9 - 533.2 eV

Ester/amide/carboxylic anhydrides and oxygen atoms in hydroxyls or ethers

C-O

[13] [16] [17] [18] [19]

534.2 eV

Carboxylic acid

C-O

[13] [16] [17] [18] [19]

C1s

284.2 - 284.9 eV

Graphite

C

[9] [13] [14] [15]

285.4 - 286.3 eV

Ether/phenol/alcohol

C-O-

[9] [13] [14] [15]

287.2 - 287.9 eV

Carbonyl/quinone

C = O

[9] [13] [14] [15]

288.7 - 289.3 eV

Carboxyl/ester

COO

[9] [13] [14] [15]

290.2 - 290.8 eV

Carbonate, occluded CO, π-electrons in aromatic ring

C = O/C = C

[9] [13] [14] [15]