Stability of Paraffin-Insulated Nitrogen-Doped Carbon Fiber Ultramicroelectrodes

Nitrogen-doped carbon materials can facilitate the reduction oxygen-oxygen bonds, a key step in electroreduction of both O2 (an important reaction in energy applications) and H₂O₂ (an important reaction in sensing and biosensing). Our lab previously demonstrated that thermal decomposition of urea in the presence of carbon fiber (CF) results in an N-doped carbon material that exhibits good electrocatalytic properties for H₂O₂ reduction. However, previous methods of insulating single N-doped CF via laser heating of borosilicate capillaries and epoxy to prepare ultramicroelectrodes (UMEs) seemed to adversely affect surface nitrogen contents and electrocatalytic properties. More recent work that utilized paraffin to insulate N-doped CF resulted in UMEs with improved electrocatalytic activity but also led to large variations in their electrochemical behavior. In this work, we characterize the effectiveness of paraffin sealing through voltametric measurements and evaluate the stability of paraffin-insulated N-doped CF UMEs by comparing electrochemical responses before and after amperometric experiments.