Highly durable iron single-atom catalysts for low-temperature zinc-air batteries by electronic regulation of adjacent iron nanoclusters

Atomic Aerogel Materials (or Single‐Atom Aerogels): An Interesting New Paradigm in Materials Science and Catalysis Science

“…density and reduced magnetic moment of the central Fe SACs, significantly enhancing the reactivity and antioxidant stability of FeN 4 sites). [39] The controllable pyrolysis strategy of biomass hydrogel precursors provides a favorable basis for the extensive preparation and application of carbon-based atomic aerogel catalysts.…”

“…To sum up, the AAMs in micrometer-level pores are often formed from the interconnected 2D or 1D basic support units (such as graphene nanosheets [16,34] and carbon nanotubes (or carbon nanofibers) [35,36] ), or from the direct pyrolysis of biomass hydrogels precursors, [38,39] or from the template growth (or pyrolysis) of melamine sponge foam skeleton. [41,42] The micrometer-level pores of AAMs can demonstrate at least two structural functions and advantages for the AAMs: 1) providing sufficient space to build compressible and nonrigid self-supporting macroblock materials; 2) providing abundant capillary channels to adsorb solution, shorten transfer path, and accelerate migration.…”

Dual‐Atom Catalysts for Electrochemical Energy Technologies

“…Another unique characterization tool is Mössbauer spectroscopy, which is a sensitive technique to characterize the spin properties of select metal centers, such as Fe and Sn, as magnetic moment of the metal centers has been found to impact the interactions with key reaction intermediates and hence the eventual electrocatalytic performance. [11] For instance, Wang et al [36] carried out Mössbauer spectroscopy measurements to obtain structural insights into the coordination configurations of the active sites of Fe-Co DAC embedded within N-doped carbon. The appearance of the D1, D2, and D3 doublets suggested the formation of three types of square-planar Fe II N 4 moieties in the sample in the high-, low-, and medium-spin states, respectively, and the occurrence of a minor singlet component of the iron species was due to the formation of the Fe-Co bond.…”

“…First, because of a surface energy significantly higher than that of the corresponding metal clusters and nanoparticles, aggregation of the single‐metal atoms is energetically preferred, leading to reduced electrocatalytic activity and durability. [ 11 ] To mitigate this impact, the metal loading of SACs is typically limited to a low value (≈2 wt%) [ 12 ] ; yet this compromises the overall performance. In addition, it is difficult to break the linear scaling relationships between the adsorption energies of reaction intermediates on SACs, such that the catalytic performance of SACs is typically limited in sophisticated reactions with various intermediates.…”

MOF-derived single-atom catalysts for oxygen electrocatalysis in metal–air batteries

“…As previously discussed, SACs, especially for MOF-derived SACs, have attracted increasing interest as potential electrocatalysts for AABs owing to their high atomic utilization, strong metal-support interaction, and distinctive electronic structure. 64,102,103 For instance, the M-N 4 structure is usually regarded as an active centre for the adsorption of O 2 molecules and the later breaking of OvO bonds in the ORR course. Huang and coworkers synthesized N-doped carbon flakes with confined Fe single atoms that were loaded onto carbon cloth (Fe-SA-NC@CC) for AABs, where the excellent cooperation between the inherent ORR activity of Fe-SA and fast ion/electron transport of N-doped carbon flakes on CC led to enhanced ORR activity (Fig.…”