Highly Active and Sulfur-Resistant Fe-N₄ Sites in Porous Carbon Nitride for the Oxidation of H₂ S into Elemental Sulfur

Iron-based catalysts have been widely studied for the oxidation of H₂ S into elemental S. However, the prevention of iron sites from deactivation remains a big challenge. Herein, a facile copolymerization strategy is proposed for the construction of isolated Fe sites confined in polymeric carbon nitride (CN) (Fe-CNNχ). The as-prepared Fe-CNNχ catalysts possess unique 2D structure as well as electronic property, resulting in enlarged exposure of active sites and enhancement of redox performance. Combining systematic characterizations with density functional theory calculation, it is disclosed that the isolated Fe atoms prefer to occupy four-coordinate doping configurations (Fe-N₄ ). Such Fe-N₄ centers favor the adsorption and activation of O₂ and H₂ S. As a consequence, Fe-CNNχ exhibit excellent catalytic activity for the catalytic oxidation of H₂ S to S. More importantly, the Fe-CNNχ catalysts are resistant to water and sulfur poisoning, exhibiting outstanding catalytic stability (over 270 h of continuous operation), better than most of the reported catalysts.