Electrochemical Reactivity Investigation of Urea Oxidation Reaction in Nichrome/Nitrogen Doped Carbon Nanofibers Synthesized by CVD Method

摘要

Urea oxidation reaction (UOR) catalysts are being extensively studied due to the affordability, effortlessness of storage and shipment, non-toxic and non-combustible characteristics of urea. Additionally, urine and urea-containing wastes are being explored as fuels, sources for generating electricity and treating waste water simultaneously in urea fuel cells (UFC). Herein, we report the urea oxidation reaction detected for nitrogen (N) doped carbon nanofibers (CNFs) grown on nichrome (NiCr) foil by chemical vapor deposition (CVD) method and study its various electrochemical parameters to determine its capability as urea fuel cell catalyst. Nickel (Ni) and chromium (Cr) metal particles were observed inside the CNFs structure as an alloy. Ni has been reported to be the most promising catalysts among transition metal catalysts. In this study, we have explored the possibility of a bimetallic transition metal/nitrogen doped carbon supported catalyst to overcome the large overpotentials exhibited by individual Ni-based catalysts for urea oxidation. The Tafel slope was found to be 640 mV/dec with diffusion coefficient D equal to 4.312x10(-13) cm(2)/s and the anodic transfer coefficient equal to 0.472. The charge transfer impedance was also calculated at 0 V and 0.4 V (onset potential) from the Nyquist plots. Our study revealed that NiCr NCNFs (Nichrome/nitrogen doped carbon nanofibers) exhibited significant UOR in variable molar concentrations of urea in 1 M KOH, making it a suitable candidate for urea oxidation reaction.