Bridge Bonded Oxygen Ligands between Approximated FeN₄ Sites Confer Catalysts with High ORR Performance

Abstract

The applications of the most promising Fe-N-C catalysts are prohibited by their limited intrinsic activities. Manipulating the Fe energy level through anchoring electronwithdrawing ligands is found effective in boosting the catalytic performance.However,such regulation remains elusive as the ligands are only uncontrollably introduced oweingt otheir energetically unstable nature.H erein, we report ar ational manipulation strategy for introducing axial bonded Otothe Fe sites,a ttained through hexa-coordinating Fe with oxygen functional groups in the precursor.M oreover,t he Om odifier is stabilized by forming the Fe À O À Fe bridge bond, with the approximation of two FeN 4 sites.The energy level modulation thus created confers the sites with an intrinsic activity that is over 10 times higher than that of the normal FeN 4 site.O ur finding opens an ovel strategy to manage coordination environments at an atomic level for high activity ORR catalysts.

A Versatile Approach to Boost Oxygen Reduction of Fe‐N4 Sites by Controllably Incorporating Sulfur Functionality

“…For comparison, fitting of the reference FePc (Figure S7b: Supporting Information) also resulted in about 4 N atoms (bond length 1.918 Å). Besides, there existed an O atom on Fe-N 4 moieties in FeNC-SN-2, [18,25,32,33] in correspondence with the result of XANES.…”

MnN4 Oxygen Reduction Electrocatalyst: Operando Investigation of Active Sites and High Performance in Zinc–Air Battery

“…[ 5–8 ] Featuring with atomically dispersed and uniformly distributed metal centers, recently, transition metal single‐atomic‐site (SAS) catalysts with MNC structures have drawn intensive research attention and hold great potential to substitute Pt in ORR under alkaline condition. [ 9–23 ] Among them, Fe‐based SAS catalysts exhibit excellent ORR activities; however, their performances after being assembled in metal–air batteries are not satisfactory. [ 21–24 ] It is generally believed that the ORR reaction is limited by the difficulty of *OH desorption from the active sites of SAS catalysts, which is dependent on the nature of the transition metal.…”

“…[ 9–23 ] Among them, Fe‐based SAS catalysts exhibit excellent ORR activities; however, their performances after being assembled in metal–air batteries are not satisfactory. [ 21–24 ] It is generally believed that the ORR reaction is limited by the difficulty of *OH desorption from the active sites of SAS catalysts, which is dependent on the nature of the transition metal. [ 23,24 ] Hence, exploring SAS catalysts with metal sites that have suitable adsorption ability to *OH is a promising way to obtain high‐performance ORR catalysts.…”

Reconstructing 1D Fe Single‐atom Catalytic Structure on 2D Graphene Film for High‐Efficiency Oxygen Reduction Reaction

“…Finally, the staggered layer‐like 1D nanocolumns, containing two kinds of Fe nanostructures (FeN 4 −FeN 4 and FeN 4 −O−FeN 4 ) with different interlayer spacing (3.19 Å and 3.32 Å, respectively) were formed and grew like a forest. Furthermore, Xing and co‐workers reported a similar Fe−O−Fe bridge structure, OFeN 4 −O−FeN 4 −O with the Fe center saturated by six coordinates, in Fe−N−C catalysts synthesized by chelating Fe with oxygen‐rich carbon precursors after high‐temperature pyrolysis [23] . The corresponding Fe−O−Fe bridge bond was formed by approximating two FeN 4 sites through increasing Fe doping level.…”