Hierarchically mesoporous carbon spheres coated with a single atomic Fe–N–C layer for balancing activity and mass transfer in fuel cells

Abstract

Novel cost‐effective fuel cells have become more attractive due to the demands for rare and expensive platinum‐group metal (PGM) catalysts for mitigating the sluggish kinetics of the oxygen reduction reaction (ORR). The high‐cost PGM catalyst in fuel cells can be replaced by Earth‐abundant transition‐metal‐based catalysts, that is, an Fe–N–C catalyst, which is considered one of the most promising alternatives. However, the performance of the Fe–N–C catalyst is hindered by the low catalytic activity and poor stability, which is caused by insufficient active sites and the lack of optimization of the triple‐phase interface for mass transportation. Herein, a novel Fe–N–C catalyst consisting of mono‐dispersed hierarchically mesoporous carbon sphere cores and single Fe atom‐dispersed functional shells are presented. The synergistic effect between highly dispersed Fe‐active sites and well‐organized porous structures yields the combination of high ORR activity and high mass transfer performance. The half‐wave potential of the catalyst in 0.1 M H2SO4 is 0.82 V versus reversible hydrogen electrode, and the peak power density is 812 mW·cm−2 in H2–O2 fuel cells. Furthermore, it shows superior methanol tolerance, which is almost immune to methanol poisoning and generates up to 162 mW·cm−2 power density in direct methanol fuel cells.

General Carbon-Supporting Strategy to Boost the Oxygen Reduction Activity of Zeolitic-Imidazolate-Framework-Derived Fe/N/Carbon Catalysts in Proton Exchange Membrane Fuel Cells

“…The peaks located at 2.1 and 1.63 Å could be indexed to the Fe−Fe and Fe−N bonds, respectively. 26,45 The main peak at 2.1 Å supports Fe species mainly in metallic nanoparticles formed in the Fe/N/Carbon catalyst. These nanoparticles are assigned to be γ-Fe according to selective electron diffraction analysis (Figure S2).…”

Strategic design of Fe and N co-doped hierarchically porous carbon as superior ORR catalyst: from the perspective of nanoarchitectonics

“…To avoid such undesirable loss of surface area in electrochemical reactions, the design of nanoarchitecture of catalyst (or electrode) materials must be considered in a more strategic way to expose as much surface area as possible to the surrounding electrochemical environment. [22][23][24][25][26] Herein, we rst prepare hollow microporous carbon (HMC, involving micro-and macropores) and hierarchically porous carbon (HPC, involving micro-, meso-and macropores) by direct-carbonization of the modied ZIF-8. 20,[27][28][29] Electrochemical behaviors of both samples are then compared to that of ZIF-8 derived microporous carbon (MPC, mainly involving micropores) to carefully examine the effect of different nanoarchitectures in the context of ORR.…”

“…To avoid such undesirable loss of surface area in electrochemical reactions, the design of nanoarchitecture of catalyst (or electrode) materials must be considered in a more strategic way to expose as much surface area as possible to the surrounding electrochemical environment. 22–26…”

Rare‐Earth Single‐Atom Catalysts: A New Frontier in Photo/Electrocatalysis

“…In recent years, the use of transition‐metal‐based SACs [ 29–31 ] and precious‐metal‐based SACs [ 32–34 ] has developed rapidly, especially in the field of energy catalysis. In particular, research has focused on Fe, [ 35–37 ] Co, [ 38,39 ] Ni, [ 40,41 ] Mn, [ 42 ] Pt, [ 43,44 ] Ir, [ 45–47 ] Pd. [ 48,49 ] Owing to the strong atom–support interactions, the coupling of the metal and ligand orbitals in the support can result in changes in the d‐band center (ε d ) of the metal atoms, [ 50,51 ] and this spin‐orbit coupling, which results in a range of electronic states, is key to the success of heterogeneous catalysis with metal‐based SACs.…”