A nitrogen-doped mesoporous carbon containing an embedded network of carbon nanotubes as a highly efficient catalyst for the oxygen reduction reaction

Abstract

A nitrogen-doped mesoporous carbon containing a network of carbon nanotubes (CNTs) was produced for use as a catalyst for the oxygen reduction reaction (ORR). SiO2 nanoparticles were decorated with clusters of Fe atoms to act as catalyst seeds for CNT growth, after which the material was impregnated with aniline. After polymerization of the aniline, the material was pyrolysed and the SiO2 was removed by acid treatment. The resulting carbon-based hybrid also contained some Fe from the CNT growth catalyst and was doped with N from the aniline. The Fe-N species act as active catalytic sites and the CNT network enables efficient electron transport in the material. Mesopores left by the removal of the SiO2 template provide short transport pathways and easy access to ions. As a result, the catalyst showed not only excellent ORR activity, with 59 mV more positive onset potential and 30 mV more positive half-wave potential than a Pt/C catalyst, but also much longer durability and stronger tolerance to methanol crossover than a Pt/C catalyst.

N-doped carbon nanotubes containing a high concentration of single iron atoms for efficient oxygen reduction

“…35 High porosity has been identified as being favorable for efficient mass transfer and minimizing the ion diffusion distance. 25 The CNT@Fe-N-PC catalyst prepared has a high BET surface area, high pore volume and high content of Fe-N x sites, and can therefore be reasonably expected to display excellent ORR performance.…”

“…[20][21][22] The above mentioned synthesis process is time-consuming and costly; therefore, it is not applicable for the large-scale fabrication of the catalyst. [23][24][25] Furthermore, it is inevitable that some active Fe-N x sites are removed during the acid leaching process, thus compromising catalytic activity. 26 Most importantly, the performance of the catalyst obtained is still unsatisfactory, that is, the overpotential versus a commercial Pt/C catalyst is generally more than 60 mV.…”

A facile synthetic strategy for iron, aniline-based non-precious metal catalysts for polymer electrolyte membrane fuel cells

“…Li et al . synthesized a Fe-N-CNT catalyst with a half-wave potential that was 30 mV more positive than Pt/C catalysts in alkaline electrolytes 21 . Currently, the low material costs of PANI-based catalysts, compared to Pt-based catalysts, are outweighed by the high manufacturing costs arising from the complicated and time-consuming processes for production of PANI-based catalysts.…”

Sulfur‐Doped Porphyrinic Carbon Nanostructures Synthesized with Amorphous MoS2 for the Oxygen Reduction Reaction in an Acidic Medium

“…With increasing weight of the MoS 2 precursor,the intensity ratio of the Mo/S/PC samples increased. [45][46][47][48][49][50][51] As previously shown in the comparison in Figure 4, Mo/S/PC-10 and Mo/S/PC-30 exhibited considerably enhanced ORR activity,t hat is, larger specific activities and higher half-wavep otentials than those of PC. Figure 6s hows the nitrogen adsorption-desorption isotherms for the samples.…”