Polypyrrole‐Derived Nitrogen and Oxygen Co‐Doped Mesoporous Carbons as Efficient Metal‐Free Electrocatalyst for Hydrazine Oxidation

Abstract

We demonstrate that polypyrrole-derived nitrogen and oxygen co-doped mesoporous carbons can serve as efficient, metal-free electrocatalysts for hydrazine oxidation reaction, with low overpotential and high current density. The materials' structures and the nature and type of their included dopants, which can be controlled by varying the synthetic conditions, can affect the electrocatalytic properties of the materials.

Superaerophobic graphene nano-hills for direct hydrazine fuel cells

“…It is worth mentioning here that a higher current density (13 mA cm − 2 vs SCE at 0 V with a scan rate of 50 mV s − 1 ) and a lower onset potential (−0.42 V vs SCE) were observed for our VGNH-45 compared to various carbon-based materials utilized for hydrazine oxidation, making it one of the best reported carbon-based materials for hydrazine oxidation. For instance, poorer current density (~5 mA cm − 2 vs SCE at 0 V with a scan rate of 50 mV s − 1 ) and higher onset potential (−0.36 V vs SCE) were observed for the dualdoped mesoporous carbon reported by Meng et al 4 compared to our VGNH-45 freestanding electrode. Furthermore, our electrode takes advantage of its facile direct growth avoiding the utilization of binding agents that lead to deteriorated performance toward hydrazine oxidation.…”

“…3 In response, various earth-abundant low-cost metallic catalysts have been extensively explored by various research groups around the globe, but these catalysts suffer from poor stability due to the formation of inactive oxide layers on their surfaces during or before the oxidation step of hydrazine. 4 On the other hand, carbon-based nanomaterials (graphene, carbon nanotubes and mesoporous carbon) present a solution to these issues partially because of their stability in strongly alkaline and acidic conditions. 5 Moreover, these materials possess high intrinsic electrical conductivity that facilitates the electron transfer processes for hydrazine oxidation along with high surface area.…”

“…First, apart from the high intrinsic conductivity of carbon-based materials, the utilization of a binder is necessary for most of these nanocatalysts simply because of their powdered nature. 4,5,8 Hence, the added 'dead volume' reduces the number of available active sites for hydrazine oxidation despite the high intrinsic surface area of these nanomaterials often prepared at high temperatures. Second, in particular for hydrazine oxidation, the onset potential is still higher for reported carbon-based materials, which ultimately hampers the overall energy conversion efficiency of these liquid-based fuel cells.…”

“…For instance, Li et al 7 showed that a complex of graphene and carbon nanotubes can be effectively utilized for the oxygen reduction reaction on the anode side of the fuel cell. Meng et al 4 utilized mesoporous carbon for hydrazine oxidation with an onset potential of only − 0.36 vs saturated calomel electrode (SCE), which is the lowest value achieved for carbon-based materials. However, there is still considerable room for further development of carbon-based electrocatalysts for various fuel-cell applications, including hydrazine oxidation, based on the following aspects.…”

Encapsulated MnO in N-doping carbon nanofibers as efficient ORR electrocatalysts

“…However, the multistep electron transfer of ORR leads to sluggish kinetics and a large overpotential, which is related to O 2 adsorption on the electrode surface and the O-O bond cleavage [5][6][7]. Ptbased materials are effective eletrocatalysts, which can promote the reaction and reduce the overpotential through a one-step four electron transfer process [8][9][10][11][12]. The high cost of Pt-based materials hinders the applications in broad commercialization [13][14][15].…”