Highly Active and Sulfur‐Resistant Fe–N₄ Sites in Porous Carbon Nitride for the Oxidation of H₂S into Elemental Sulfur

Abstract

Iron‐based catalysts have been widely studied for the oxidation of H2S 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 H2S. As a consequence, Fe‐CNNχ exhibit excellent catalytic activity for the catalytic oxidation of H2S 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.

A Unique Fe–N4 Coordination System Enabling Transformation of Oxygen into Superoxide for Photocatalytic CH Activation with High Efficiency and Selectivity

“…The same results are displayed in the Fe 2p XPS spectrum (Figure S7, Supporting Information). [49][50][51] The N 1s XPS spectrum of SA-Fe-TCN features three peaks at 395.1, 396.4, and 397.8 eV (Figure 3b). The first two peaks are typically found in CN and can be assigned to pyrrolic and pyridinic N, respectively.…”

Supported Metal Single‐Atom Thermocatalysts for Oxidation Reactions

“…The excellent activity as well as steam and sulfur-resistance of the emblematic Fe-N-C system -consisting here of Fe-N4 centers confined in polymeric carbon nitride through a copolymerization approach -for gas-phase H2S oxidation into elemental sulfur was recently reported by Lei et al [263]. Based on DFT calculations, the authors propose H2S and O2 dissociative adsorptions at (probably separate) Fe-N4 centers, leading to HS-Fe-N4 and O* radical species, which in turn exothermally generate S and H2O (Figure 8a).…”

Highly Poison‐Resistant Single‐Atom Co–N4 Active Sites with Superior Operational Stability over 460 h for H2S Catalytic Oxidation

“…It is noted that the released CN X and CH X fragments act as a soft template for pore formation during the pyrolysis, thus, expanding the BET surface area of xCo-N/NC. [43] For comparison purposes, sample of Co nanoparticles (Co loading of 5.2 wt%) dispersed on NC surface (Co-NPs/NC) was prepared. The TEM images in Figure S5a-c (Supporting Information) reveal that the Co nanoparticles are dispersed on the nitrogen-doped carbon, indicating the aggregation of Co atoms.…”