B‐Doped Fe/N/C Porous Catalyst for High‐Performance Oxygen Reduction in Anion‐Exchange Membrane Fuel Cells

Abstract

The development of high-performance non-precious metal catalysts for the oxygen reduction reaction (ORR) as an alternative to platinum-based counterparts in fuel cells is highly desirable but challenging. In this study, a facile approach for preparing a porous boron-bearing Fe/N/C catalyst by pyrolysis was reported. The obtained FeCNB-900 with a high surface area (784 m 2 g À 1 ) favored a 4e À -reduction pathway for ORR, with a half-wave potential of~0.86 V vs. RHE and high stability in 0.1 M KOH. Furthermore, anion-exchange membrane fuel cells (AEMFCs) with the use of the FeCNB-900 composite as the cathode catalyst exhibited a maximal power density of 0.172 W cm À 2 without back pressure, revealing its promising potential for application in fuel cells and metal-air batteries. Results demonstrated that the additional doping of B into Fe/N/ C leads to a significant increase in the specific surface area of the catalyst composite and can adjust surface polarities as well as electronic properties and provide more active sites to impart a synergistic effect for boosting catalytic ORR performance.

New insights into the key bifunctional role of sulfur in Fe–N–C single-atom catalysts for ORR/OER

“…By adjusting the electronic structure and improving the electronic conductivity, large atomic radius S atom doping of the carbon matrix has been carried out to elevate ORR activity effectively. 10–16 Zhou and Sun et al synthesized an S-doped Fe–N–C SAC for the first time with a high surface area and S-doping level to realize excellent ORR activity for a high kinetic current of 23 A g −1 at 0.80 V in 0.1 M H 2 SO 4 solution. 17 After that, Tang, 18 Li, 19 Wang, 20 and others 16,21–23 have realized S-doped Fe–N–C SACs for ORR with high half-wave potentials, firm stability, high methanol tolerance and successful application in Zn–air batteries.…”

Fe, B, and N Codoped Carbon Nanoribbons Derived from Heteroatom Polymers as High-Performance Oxygen Reduction Reaction Electrocatalysts for Zinc–Air Batteries

“…However, the ORR performance of Fe–N–C was further improved by the introduction of B elements. As shown in Figure a, it can be concluded that B doping in the Fe–N–C system affects the charge balance of the adjacent carbon and improves the turnover frequency of Fe sites, which promotes the ORR activity. ,, …”

“…This result was attributed to the introduction of a three-dimensional crosslinked structure of MFs, which brought a larger specific surface 4a, it can be concluded that B doping in the Fe−N−C system affects the charge balance of the adjacent carbon and improves the turnover frequency of Fe sites, which promotes the ORR activity. 45,57,58 For the purpose of further evaluating the influence of Fe, B, and N codoping effect on the ORR in acidic conditions, the electrocatalytic activity of all samples was also investigated in an O 2 -saturated 0.1 M HClO 4 aqueous solution. Obviously, Fe−B−N−C had the most positive oxygen reduction potential compared to other samples in the CV curves (Figure S12a).…”

“…Researches have shown that the introduction of transition metals (Fe, Co, Mn, etc.) into nitrogen-doped carbon can significantly improve ORR properties. − In particular, Fe and N codoped carbon has outstanding ORR performance due to the formation of a highly active FeN 4 site. − However, there is still need for further improvement to meet the requirements of practical applications. , Recent studies have shown that it can be enhanced by introducing the third heteroatoms. − Attractively, the introduction of an electron-deficient boron into the carbon framework can destroy the neutrality of the carbon matrix and create potential active points. − For instance, Yuan et al. demonstrated that the boron-containing carbon skeleton loaded with Fe–N x has higher ORR properties than Fe–N–C .…”

Dissociative Oxygen Reduction Reaction Mechanism on the Neighboring Active Sites of a Boron-Doped Pyrolyzed Fe–N–C Catalyst

“…Because the ORR on the B-doped pyrolyzed Fe−N−C system is unable to produce hydrogen peroxide in both associative and dissociative pathways, the ORR on this system follows the 4e-reduction pathway, which is also in direct agreement with the experimental results. 16,17…”