Table 1.

Functional groups identified from FT-IR spectra of the samples.

Wavenumber (cm−1)	Types of vibration	Functional groups	References in the article
3400–3200	Stretching	-OH, –NH	[5]
2926	Asymmetrical stretching	C–H	[5]
2857	Symmetrical stretching	C–H	[5]
1657	Stretching	C=O (Amide I)	[6]
1640	Stretching	C=O	[6]
1580	Bending, stretching	-NH, –NH (Amide II)	[5], [6]
1400	Stretching	C–N	[7]
1050	Stretching	C–O	[8]
872, 800	Out-of-plane bending	C–H of phenazine skeleton	[9]