Altering the spin state of Fe-N-C through ligand field modulation of single-atom sites boosts the oxygen reduction reaction

Fe/N/S Co-doped Porous Carbon from the Co-processing Residue of Coal and Heavy Oil for an Efficient Oxygen Reduction Reaction

“…Compared with recently reported ORR electrocatalysts under alkaline and acidic conditions (Table ), CR–MN–KOH-800 has favorable ORR performance, relatively simple raw materials, and synthetic steps can reasonably utilize coal liquefaction solid wastes. Further study for tuning the dispersion behavior and electronic structure of FeN x active sites in these kinds of carbonaceous solid wastes would be a prospective avenue to gain effective ORR electrocatalysts with practical application values. , …”

“…Further study for tuning the dispersion behavior and electronic structure of FeN x active sites in these kinds of carbonaceous solid wastes would be a prospective avenue to gain effective ORR electrocatalysts with practical application values. 56,57 ■ CONCLUSIONS In summary, under alkaline and acidic conditions, the ORR activity of the electrocatalyst prepared with CR components was better than that of the electrocatalyst prepared with CR toluene-soluble or toluene-insoluble substances. The CR-based porous carbon electrocatalyst (CR−MN−KOH-800) with a large specific surface area of 1326 m 2 •g −1 , rich hierarchical porous structures, high N doping, and self-doping of Fe and S was prepared via KOH activation and MN doping.…”

In Situ X‐ray Absorption Spectroscopy of Metal/Nitrogen‐doped Carbons in Oxygen Electrocatalysis

“…[78] In 2022, Xue et al realized the electron spin-state modulation of Fe active centers in SACsbased FeÀ NÀ C ranging from a low-spin state (LS) for FeN 5 (FeÀ N 5 À LS) to a high-spin state (HS) for FeN 4 (FeÀ N 4 À HS) and FeN 3 (FeÀ N 3 À HS) by converting defect-rich pyrrolic N-coordinated FeN x sites, which tune the electron readily penetrating the antibonding π-orbital of oxygen. [79] The designed FeÀ N 4 À HS catalyst with high spin state (S 5/2 ) displays excellent acidic/alkaline ORR activity (Figure 6a). Moreover, Li et al obtained a Fe single-atom catalyst (FeÀ NÀ C/rGO SAC) by pyrolyzing the hybrid of ZIF-8 and graphene oxide (GO).…”

“… Structure of active sites in M−N−C ‐based oxygen electrocatalysis (a) The electron spin‐state modulation of Fe active centers in SACs‐based Fe−N−C identified by activity measurement and theoretical calculations. (Reproduced with permission from [79], copyright 2022, Elsevier). (b) The schematic illustration of the formation of Fe‐SAs/NSC, Co‐SAs/NSC, and Ni‐SAs/NSC with different coordination environments, (c–e) EXAFS curves between the experimental data and the fit of (c) Fe‐SAs/NSC, (d) Co‐SAs/NSC, and (e) Ni‐SAs/NSC.…”

A bimetallic 3D interconnected metal–organic framework with 2D morphology and its derived electrocatalyst for oxygen reduction

“…[27][28][29] After pyrolysis under N 2 /Ar, ZIFs could transform into M-NC materials with N defects and abundant active sites. [30][31][32][33][34] These N atom defects could coordinatively bind to other transition metal ions, such as Fe, Ni, and Cu, [35][36][37][38][39] to obtain single-atom electrocatalysts. Among all ZIF materials, nonporous dense ZIFs show advantages, such as a high content of N and metal ions, while pores would be generated due to the volatilization of Zn during the pyrolysis of nonporous ZIFs as precursors.…”