Insights into the di fference in metal -free activation of peroxymonosulfate and peroxydisulfate
Insights into the di fference in metal -free activation of peroxymonosulfate and peroxydisulfate
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深入了解过一硫酸盐和过二硫酸盐的无金属活化差异
DOI：
10.1016/j.cej.2019.123936
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发表时间：
2020-08-15
影响因子：
15.1
通讯作者：
Hu, Chun
中科院分区：
文献类型：
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作者：
Gao, Yaowen;Zhu, Yue;Hu, Chun
据报道，由于PMS的不对称结构，过一硫酸盐（PMS）的无金属活化比过二硫酸盐（PDS）更有效。然而，我们首次报道了以石墨氮化碳为模板的氮掺杂多孔碳（NC-900）在活化PDS时表现出比PMS意外更高的催化活性，NC-900/PDS的速率常数（0.80 min（-1））是NC-900/PMS（0.46 min（-1））的1.74倍。此外，NC-900在过硫酸盐活化中显示出上级现有氮掺杂纳米碳的反应性和稳定性。实验和理论结果表明，PMS活化过程包括富电子石墨N上的PMS还原和与石墨N相邻的缺电子碳原子周围的PMS氧化，其中PMS氧化是主要反应，单线态氧（O-1（2））是主要反应物种.相比之下，PDS减少了电子的碳原子占主导地位的PDS活化NC-900的羟基自由基（（OH）-O-中心点）的产生。NC-900/PDS中大量的（OH）-O-中心点比O-1（2）具有更强的氧化能力，这是NC-900/PDS在降解有机污染物方面优于NC-900/PMS的原因。这项工作为无金属PMS和PDS活化的差异提供了深刻的见解，并为可持续环境修复设计先进的碳基催化剂提供了基本框架。
Metal-free activation of peroxymonosulfate (PMS) has been reported to be more efficient than peroxydisulfate (PDS) due to the asymmetrical structure of PMS. However, we report for the first time that the nitrogen-doped porous carbon (NC-900) templated from graphitic carbon nitride exhibits unexpectedly higher catalytic activity in the activation of PDS than PMS, as evidenced by 1.74-fold greater rate constant of NC-900/PDS (0.80 min(-1)) than that of NC-900/PMS (0.46 min(-1)). Moreover, NC-900 shows superior reactivity and stability to existing nitrogen-doped nanocarbons in persulfate activation. Experimental and theoretical results revealed that PMS activation involves PMS reduction over the electron-rich graphitic N and PMS oxidation around the electrondeficient carbon atom adjacent to graphitic N in NC-900, in which PMS oxidation is the main reaction rendering singlet oxygen (O-1(2)) the major reactive species. By contrast, PDS reduction over the electron-poor carbon atom dominates PDS activation on NC-900 for hydroxyl radical ((OH)-O-center dot) generation. The large amount of (OH)-O-center dot with stronger oxidation capability than O-1(2) contributes to the superiority of NC-900/PDS over NC-900/PMS in organic pollutant degradation. This work provides profound insights into the difference in metal-free PMS and PDS activation and presents fundamental frameworks in the design of advanced carbon-based catalysts toward sustainable environmental remediation.