Synthesis and Evaluation of Heat-treated, Cyanamide-derived Non-precious Catalysts for Oxygen Reduction

Metal-nitrogen-carbon type (M-N-C type) non-precious catalysts have been prepared using cyanamide as the nitrogen precursor and pyrolysis to improve the activity and stability. Good activity has been observed for the best catalyst prepared with 1050degree signC pyrolysis: E1/2 = 0. 77 V by RDE, and current density = 80 mA at 0. 80 V in H2/O2 fuel cell testing. M-N-C catalysts prepared using cyanamide as a nitrogen source show a complex dependence of activity on pyrolysis temperature: first increasing (up to 900degree signC), then decreasing (1000degree signC), before increasing again (1050degree signC). The reappearance of activity may relate to an increase in defects induced at higher temperature, such as a greater exposure of the edges of graphene planes. The increased hydrophilicity of the sample after pyrolysis at 1050degree signC suggests this outcome. Further study will be required to confirm the hypothesis.