Table 2.

Collected elemental compositions in atomic percentages of the samples by X-ray photoelectron spectroscopy (XPS).

Samples	C1s	O1s	N1s	S2p	O1s/C1s	N1s/C1s	S2p/C1s
PET	69.7	30.3	0	0	0.435	0	0
PET_DC	58.4	40.9	0.7	0	0.700	0.012	0
FU3	63.4	35.7	0	0.2	0.563	0	0.003
FU4	63.7	34.5	0.2	1.6	0.542	0.003	0.025
FU5	63.6	34.4	0.2	1.8	0.541	0.003	0.028
FU6	63.7	35.7	0.1	0.5	0.560	0.002	0.008
FU7	63.8	35.6	0.1	0.5	0.558	0.002	0.008