Table 2. Contents of MCNs Obtained from the Fitting Results of the C 1s Spectrum.

samples	peaks	binding energy (eV)	oxygen form	atomic ratio (%)
MCN1	1	284.7	sp2C	54.68
	2	285.7	C–H/C–O/C–N	39.70
	3	288.8	O–C=O, N–C=O	5.32
MCN2	1	284.8	sp2C	73.12
	2	285.8	C–H/C–O	16.26
	3	287.1	C=O	10.62
MCN3	1	284.8	sp2C	56.70
	2	285.3	C–H/C–O	29.04
	3	286.4	C–O	14.25
MCN4	1	284.8	sp2C	59.36
	2	285.5	C–H/C–O	35.34
	3	287.4	C=O	5.29