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 1050 degrees C pyrolysis: E-1/2 = 0.77 V by RDE, and current density = 80 mA at 0.80 V in H-2/O-2 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 900 degrees C), then decreasing (1000 degrees C), before increasing again (1050 degrees C). 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 1050 degrees C suggests this outcome. Further study will be required to confirm the hypothesis.