Heteroatoms doped C3N4 as high performance catalysts for the oxygen reduction reaction

Different kinds of carbon nitride were successfully synthesized through pyrolyzing the precursors. Their physical properties were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. While the electrochemical properties were measured by cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The results showed that the sulfur-doped carbon nitride exhibited better electrochemical catalytic properties towards oxygen reduction reaction. Most importantly, the onset potential of sulfur-doped carbon nitride was 0.77 V (vs. RHE), which positively shifted 40 mV than that of the carbon nitride. The calculation of kinetics parameters showed that it occurred through an approximately four electron pathway with a lower Tafel slope (115 mV/decade). Furthermore, the sulfur-doped carbon nitride also presented excellent stability and methanol tolerance.