Single-atom catalysts (SACs) have been widely applied in electrocatalysis, photocatalysis and advanced oxidation processes. However, the synthesis of Fe SACs supported by layered g-C₃N₄ remains challenging due to the high temperatures required for Fe single-atom (Fe-SA) sites formation, which can lead to the decomposition and curling of g-C₃N₄. Herein, Fe SACs loaded on layered g-C₃N₄ (Fe-SA@CN) were synthesized via an one-step pyrolysis using the pre-coordination metal precursor (hemin). The pre-coordinated structure in hemin prevented Fe atoms aggregation, while the planar structure of hemin suppressed the curling of g-C₃N₄ at high temperature. The structures of the resulting material, including the atomically dispersed Fe-SA sites and its coordination environment (Fe-N₄), were characterized by AC-STEM and XAFS. The doping of Fe-SA sites facilitates the fracture of C-N bonds in pyridinic N and boosts the recombination of C-C bonds, thereby lowering the initial temperature of thermal decomposition of g-C₃N₄ and improving the quality of the carbonization residue. Experimental tests and DFT calculations demonstrate that Fe-SA sites effectively decrease the adsorption energy of PMS, facilitating electron transfer processes. The Fe-SA@CN, with a Fe loading of 2.03 wt%, performs best in activating PMS for the degradation of aromatic compounds bearing electron-donating groups, which are mainly attacked by ¹O₂ generated on Fe-SA sites (above 90% ¹O₂ selectivity). This study highlights the role of precursor in the synthesis of single-atom catalysts, and provides insight for developing SACs for advanced oxidation processes.

单原子催化剂（SAC）已广泛应用于电催化、光催化和高级氧化过程。_{然而，由层状gC 3} N ₄支撑的Fe SAC的合成仍然具有挑战性，因为Fe单原子（Fe-SA）位点的形成需要高温，这可能导致gC ₃ N ₄的分解和卷曲。在此，使用预配位金属前体（氯化血红素）通过一步热解合成了负载在层状gC ₃ N ₄ (Fe-SA@CN)上的Fe SAC 。_{氯化血红素的预配位结构阻止了Fe原子的聚集，而氯化血红素的平面结构抑制了gC 3} N ₄的卷曲在高温下。所得材料的结构，包括原子分散的 Fe-SA 位点及其配位环境 (Fe-N ₄ )，通过 AC-STEM 和 XAFS 进行了表征。_{Fe-SA位点的掺杂有利于吡啶N中CN键的断裂，促进CC键的复合，从而降低gC 3} N ₄热分解起始温度提高炭化渣的质量。实验测试和DFT计算表明Fe-SA位点有效降低了PMS的吸附能，促进电子转移过程。Fe-SA@CN的Fe负载量为2.03 wt%，在激活PMS以降解带有给电子基团的芳香族化合物方面表现最佳，这些化合物主要受到Fe-SA位点上生成的¹ O ₂的攻击（高于90）% ¹ O ₂选择性）。这项研究强调了前驱体在单原子催化剂合成中的作用，并为开发高级氧化过程的 SAC 提供了见解。