Fe single atoms in nitrogen doped carbon materials (Fe-NC) have attracted plenty of attention during the last decades in the field of electrocatalysis for oxygen reduction and carbon dioxide conversion amongst others. In the cathode of proton exchange membrane fuel cells Fe-NC are the most promising solution to scarce and expensive Platinum-group-metal catalysts;^[1] In CO₂ reduction, they have achieved similar performance to that of nanostructured Au and Ag. However, their controlled synthesis and stability for practical applications remains challenging. Approaches to enhance their catalytic performance include increasing the loading of Fe single atoms, for example by decoupling high temperature pyrolysis and Fe coordination atoms, or enhancing the intrinsic activity of the FeN_x sites through engineering of the coordination environment or by creation of dual atom catalysts.^[2,3]

Currently, the utilization of Fe within these materials remains very low owing to the lack of C-N scaffolds that combine adequate micro- and mesoporosity. In this work we employ inexpensive 2,4,6-Triaminopyrimidine (TAP) with MgCl₂.6H₂O as porogen to prepare a highly porous N-doped carbon material.^[4] The hydrogen bonding between nitrogen moieties of TAP and the water molecules of the Mg salt allows an optimal interaction during pyrolysis that leads to remarkable porosity in the nitrogen-doped material (~3300 m² g^-1) and very available N sites for Fe coordination. The subsequent low temperature Fe coordination results in a highly active O₂ reduction to electrocatalyst with a mass activity 4.0 A g^-1 at 0.8 V_RHE in acid electrolyte. Additionally, the material shows near 100% Faradaic Efficiency for the CO₂ reduction to CO (FE_co = 93.5% at -0.55 V vs RHE) with one of the highest TOF reported up to date (4.5 s^-1)

Aberration corrected high-angle annular dark field scanning transmission electron microscopy with energy dispersive x-ray spectroscopy of the catalyst confirms the solely atomic Fe and N distribution pre- and post-accelerated degradation tests. In-situ nitrite stripping reveals a high active site density of 2.54×10¹⁹ sites g^-1; the remarkable porosity of the graphitic material and hierarchal structure ensures remarkably high electrochemical active site utilisation of 42%. Ex-situ X-ray absorption extended fine structure suggests the presence of penta-coordinated FeN₅ sites, potentially enabling the stability of the active site for O₂ and CO₂ reduction.^[5]