Electronic Structure Modulation of Graphitic Carbon Nitride by Oxygen Doping for Enhanced Catalytic Degradation of Organic Pollutants through Peroxymonosulfate Activation
Electronic Structure Modulation of Graphitic Carbon Nitride by Oxygen Doping for Enhanced Catalytic Degradation of Organic Pollutants through Peroxymonosulfate Activation
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通过氧掺杂调节石墨碳氮化物的电子结构，通过过一硫酸盐活化增强催化降解有机污染物
DOI：
10.1021/acs.est.8b05246
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发表时间：
2018-12-18
影响因子：
11.4
通讯作者：
Hu, Chun
中科院分区：
文献类型：
--
作者：
Gao, Yaowen;Zhu, Yue;Hu, Chun
以尿素和草酸为前驱体，以草酸为氧源，采用简易热聚合法制备了掺氧石墨化碳氮化物(O-CN)。实验和理论结果表明，氧掺杂优先发生在两个氮配位上，形成低电子密度区和高电子密度区，从而导致O-CN的电子结构调制。结果表明，所合成的O-CN具有较高的催化活性和较好的长期稳定性，可活化过一硫酸盐(PMS)降解有机污染物。具有可调电子结构的O-CN使PMS在缺电子的C原子上氧化生成单线态氧(O-1(2))，并在富电子的O掺杂周围还原生成羟基自由基((OH)-O-中心点)和硫酸盐自由基(SO4中心点-)，其中O-1(2)是主要的活性氧物种，有助于O-CN/PMS体系的选择性反应。我们的发现不仅提出了PMS同时氧化和还原生成非自由基物种和自由基物种的新的PMS活化机理，而且为通过非金属掺杂开发高效的无金属催化剂向基于过硫酸盐的环境净化提供了有价值的见解。
Oxygen-doped graphitic carbon nitride (O-CN) was fabricated via a facile thermal polymerization method using urea and oxalic acid dihydrate as the graphitic carbon nitride precursor and oxygen source, respectively. Experimental and theoretical results revealed that oxygen doping preferentially occurred on the two-coordinated nitrogen positions, which create the formation of low and high electron density areas resulting in the electronic structure modulation of O-CN. As a result, the resultant O-CN exhibits enhanced catalytic activity and excellent long-term stability for peroxymonosulfate (PMS) activation toward the degradation of organic pollutants. The O-CN with modulated electronic structure enables PMS oxidation over the electron-deficient C atoms for the generation of singlet oxygen (O-1(2)) and PMS reduction around the electron-rich O dopants for the formation of hydroxyl radical ((OH)-O-center dot) and sulfate radical (SO4 center dot-), in which O-1(2) is the major reactive oxygen species, contributing to the selective reactivity of the O-CN/PMS system. Our findings not only propose a novel PMS activation mechanism in terms of simultaneous PMS oxidation and reduction for the production of nonradical and radical species but also provide a valuable insight for the development of efficient metal-free catalysts through nonmetal doping toward the persulfate-based environmental cleanup.