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

Abstract

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{degree sign}C 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 900{degree sign}C), then decreasing (1000{degree sign}C), before increasing again (1050{degree sign}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{degree sign}C suggests this outcome. Further study will be required to confirm the hypothesis.

Enhanced electrocatalytic activity of nitrogen-doped multi-walled carbon nanotubes towards the oxygen reduction reaction in alkaline media

“…It needs to be stressed that both CM and DCDA have been employed by other research groups as precursors for N-doping of carbon nanomaterials, 14,60,61,[82][83][84] however, to our knowledge no such comparative study on the oxygen reduction behaviour on CM-and DCDA-derived NCNTs has been reported as yet.…”

Establishing reactivity descriptors for platinum group metal (PGM)-free Fe–N–C catalysts for PEM fuel cells

“…12,26,[61][62][63] Over the past decades, studies to identify more active Fe-N-C catalysts have largely relied on empirical approaches involving the systematic variation of elemental precursors and/or synthesis conditions to prepare Fe-N-C materials and their correlation with the resulting kinetic current density ( J kin ) and other lump performance metrics of ORR catalysts. 7,36,[64][65][66] While this approach has had some success in the early stages of Fe-N-C materials development, it now seems to have reached its limitation, with stalled progress in the power and durability performance of Fe-N-C cathodes in PEMFCs in the last years, despite intense international efforts. Novel and more rational approaches are needed in order to deconvolute the overall activity and durability of Fe-N-C catalysts into the contributions arising from different Fe-based active sites, in order to identify the most active and/or most durable sites and to develop synthetic strategies to selectively optimize the number of such sites.…”

Recent Advancements in Transition Metal‐Nitrogen‐Carbon Catalysts for Oxygen Reduction Reaction

“…In recent years, in addition to the above macrocycles, a series of low‐cost N‐containing precursors such as polyacrylonitrile (PAN), polyaniline (PANI), polypyrrole (PPy), ethylenediamine (EN), and cyanamide (CA) were used in the fabrication of M−N/C catalysts by doping carbon supports with these metal‐coordinating materials . For example, Gu et al .…”