Abstract Heterogeneous catalysts with ultra-small clusters and atomically dispersed (USCAD) active sites have gained increasing attention in recent years. However, developing USCAD catalysts with high-density metal sites anchored in porous nanomaterials is still challenging. Here, through the template-free S-assisted pyrolysis of low-cost Fe-salts with melamine (MA), porous alveolate Fe/g-C3N4 catalysts with high-density (Fe loading up to 17.7 wt%) and increased USCAD Fe sites were synthesized. The presence of a certain amount of S species in the Fe-salts/MA system plays an important role in the formation of USCAD S-Fe-salt/CN catalysts; the S species act as a “sacrificial carrier” to increase the dispersion of Fe species through Fe-S coordination and generate porous alveolate structure by escaping in the form of SO2 during pyrolysis. The S-Fe-salt/CN catalysts exhibit greatly promoted activity and reusability for degrading various organic pollutants in advanced oxidation processes compared to the corresponding Fe-salt/CN catalysts, due to the promoted accessibility of USCAD Fe sites by the porous alveolate structure. This S-assisted method exhibits good feasibility in a large variety of S species (thiourea, S powder, and NH4SCN) and Fe salts, providing a new avenue for the low-cost and large-scale synthesis of high-density USCAD metal/g-C3N4 catalysts.

中文翻译：

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一种简便的硫辅助合成具有超小簇和原子分散 Fe 位点的多孔蜂窝状 Fe/g-C3N4 催化剂的方法

摘要 近年来，具有超小团簇和原子分散（USCAD）活性位点的多相催化剂越来越受到关注。然而，开发具有锚定在多孔纳米材料中的高密度金属位点的 USCAD 催化剂仍然具有挑战性。在这里，通过使用三聚氰胺 (MA) 对低成本 Fe 盐进行无模板 S 辅助热解，高密度多孔蜂窝状 Fe/g-C3N4 催化剂（Fe 负载量高达 17.7 wt%）和增加的 USCAD Fe 位点被合成。Fe-salts/MA体系中一定量S物种的存在对USCAD S-Fe-salt/CN催化剂的形成起着重要作用；S 物种充当“牺牲载体”，通过 Fe-S 配位增加 Fe 物种的分散，并通过在热解过程中以 SO2 的形式逸出而产生多孔蜂窝状结构。与相应的 Fe-salt/CN 催化剂相比，S-Fe-salt/CN 催化剂在高级氧化过程中降解各种有机污染物的活性和可重用性大大提高，这是由于多孔蜂窝状结构促进了 USCAD Fe 位点的可及性。这种 S 辅助方法在多种 S 物质（硫脲、S 粉末和 NH4SCN）和 Fe 盐中表现出良好的可行性，为低成本和大规模合成高密度 USCAD 金属/g 提供了新途径-C3N4 催化剂。