Table 2.

Assignments of the O1s, C1s, and N1s peaks according to the literatures [25,26,27].

C1s		O1s		N1s
Species	Range(eV)	Species	Range(eV)	Species	Range(eV)
C=C	284.6	C=O,conj [28]	530.7	N-Pyr.	398.5
C-O,C-N	286.3	C=O	531.5	-NH2	400.0
C=O	287.2	C-O-C	532.6	N-Quat.	401.2
COOR	288.9	C-O	533.5	N-Pyr. Ox.	402.5
		H2O	534.0