In this work, we introduce our recent finding that the carbon fiber paper (CFP) treated by simple air annealing (OCFP) could be used for exceptionally high-performance electrochemical nitrite sensing. The air-annealing process endows the pristine CFP with higher defective edge/plane sites, more oxygen-containing functional groups, higher roughness, and improved wettability. The electrochemical studies show that the OCFP exhibits excellent sensing performance for nitrite, with an ultralow determination limit of 0.1 μM and a detection limit of 0.07 μM, an ultrawide linear determination range of 0.1-3838.5 μM, a fast current response of 1 s, and a high sensitivity of 930.4 μA mM-1 cm-2. These performance values are comparable or even superior to those for most reported noble- or transition-metal-based advanced nitrite sensors. Besides, this electrode also presents satisfactory stability, reproducibility, and feasibility of nitrite sensing in food samples. As an ideal monolithic and metal-free catalyst with ultrahigh and stable detection performance, the OCFP has a high potential to be integrated into next-generation electrochemical sensing devices.
Keywords: carbon fiber paper; electrochemical sensor; food sample; nitrite; surface engineering.