Radio frequency O2-plasma treatment of carbon felts: stoichiometric insight into C1s and O1s XPS with correlated Raman and SEM characterization

Surface functionalization of carbon plays a key role in tailoring their interfacial properties for applications in energy storage, energy conversion, structural composites, etc. In this work, radio frequency (RF) O 2 -plasma was employed to tailor the surface chemistry of C-felts. The influence of plasma power and treatment duration was studied. X-ray photoelectron spectroscopy (XPS) revealed that oxygen incorporation increases upon plasma treatment with powers up to 100 W, decreasing the C/O ratio significantly, followed by partial recovery at higher powers due to ion-induced etching. High-resolution C1s and O1s spectra were deconvoluted using a stoichiometric correlation strategy to improve peak assignments. Despite the inherent complexity of O1s spectra due to peak overlap and symmetric features, a consistent interpretation was achieved. Hence, by providing a stoichiometry-driven framework we improve the accuracy and consistency of XPS analysis by correlating the deconvolution of high-resolution C1s and O1s spectra. Raman spectroscopy confirmed the progressive increase in structural defects, with higher plasma powers and longer exposures. Scanning electron microscopy (SEM) revealed pronounced surface roughening and fiber etching after plasma. Overall, this work provides a deeper insight into surface modification of carbon felt utilizing O 2 -plasma and establishes a stoichiometric framework for interpreting complex XPS spectra of oxygen-functionalized carbons.