Metal and heteroatoms-free carbon soot obtained from atmospheric combustion of naphthalene for sensitive dissolved oxygen reduction reaction and sensing in neutral media

Metal and heteroatom-free electro-active carbon soot nanoparticles of average size 50 ± 10 nm have been prepared by simple atmospheric combustion of abundant naphthalene compound. Physicochemical characterizations by Transmission electron-microscope, Infrared, Raman spectroscopy, X-Ray diffraction, and CHN analysis techniques revealed that the soot has a graphitic core with highly defective oxygen structure composed of carbonyl, hydroxyl, ether, furan, pyran, pyrone and carboxylic acid along with aliphatic carbons on the surface. Electrochemical characterization with a bench mark redox system, Fe(CN)63− reveals the efficient conductive behaviour of the new soot material even after mixing with the anionic-Nafion membrane (Nf). The GCE/Soof-Nf showed a well-defined oxygen reduction reaction (ORR) current signal at cathodic peak potential, −0.39 V vs Ag/AgCl similar to that of the heme, hemoglobin and quinone based electrochemical systems for oxygen reduction reaction (ORR) in neutral media. Obtained ORR peak current signal is found to be 2–5 times higher than that of the current signals noticed with activated charcoal, graphite nanopowder, functionalized MWCNT and bulk gold electrodes. Rotating disc electrode and bio-potentiostat coupled flow-injection analysis techniques have been adopted to find out the kinetics and mechanism of the ORR. Utilizing the new carbon soot material, sensitive detection of dissolved oxygen with detection limit 8.6 ppb was demonstrated in neutral buffer solution.