Electrocatalytic Activity of Functionalized Carbon Paper Electrodes and Their Correlation to the Fermi Level Derived from Raman Spectra

Carbon paper electrodes are employed for different electrochemical applications such as flow batteries and fuel cells. However, redox reactions such as VO2+/VO2+ in a vanadium redox flow battery have been found to possess relatively slow kinetics, resulting in significant activation losses during operation. In this work, we demonstrate a facile and scalable method for nitrogen doping of carbon paper electrodes, leading to superior electrocatalytic activity. The effects of pyrolytic pretreatments under different conditions on the performance of carbon paper were also studied to elucidate their electrocatalytic activity from a material physics perspective, using Raman spectroscopy. The 2D Raman signature, a specific feature of the carbon structures, was employed to understand the effect of different pretreatments on the Fermi level of the carbon papers, which could help us elucidate their intrinsic electron transfer kinetics. The full wave half-maximum of the 2D Raman band and the intensity ratio I2D/IG wer...