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Sulfur-doped photocatalysts with iron-nitrogen coordination bonds by modifying graphitic carbon nitride obtained from ammonium thiocyanate pyrolysis with ferrous sulfate heptahydrate in ethanol
Optical Materials ( IF 3.9 ) Pub Date : 2021-06-05 , DOI: 10.1016/j.optmat.2021.111222
Liyuan Duan , Guoqiang Li , Shuting Zhang , Hongyu Wang , Yongle Zhao , Yongfa Zhang

The photocatalytic agent graphitic carbon nitride (g-C3N4) was synthesized by pyrolysis of ammonium thiocyanate (NH4SCN) which is commonly produced via extraction of desulfurization waste liquids as the main salt. The g-C3N4 photocatalyst was modified by treatment with different amounts of ferrous sulfate heptahydrate in ethanol, which resulted in Fe-doping and a certain degree of S-doping of the material. According to the characterization results, the modified sample eg-C3N4/FeSO4-10% with superior photocatalytic efficiency exhibited the highest specific surface area and pore volume, poor crystallinity, and a good sample polymerization degree. The existence of more C defect vacancies in the modified sample structure increased the electron density around C and N atoms in the triazine ring structure and becomes the electron capture center. At the same time, the presence of ethanol solvent promotes the formation of more Fe–N coordination bonds between a large number of lone pair electrons and metal Fe ions. In addition, with the increase of the doping amount of S element, a new impurity level is introduced, and the band gap widths of the samples become narrower. The changes of surface structure and energy band structure of the modified samples led to a significantly reduced carrier recombination rate and further promoted the production of more reactive oxygen groups. In the process of Rhodamine B (RhB) degradation as organic pollutant, the degradation can reach 98% rapidly after 60 min of visible light irradiation, which is 78% higher than g-C3N4, at a simultaneous increase of the photocatalytic reaction rate constant from 0.007 to 0.305 per min. Meanwhile, the sample eg-C3N4/FeSO4-10% also showed excellent photocatalytic activity in the NOx removal process of air pollution. Compared with the original g-C3N4, the NO removal rate increased from 64% to 75%, and the production amount of harmful intermediate NO2 decreased from 0.15 to 0.08 mg/m3.



中文翻译:

用七水硫酸亚铁在乙醇中对硫氰酸铵热解得到的石墨氮化碳进行改性,制备具有铁氮配位键的硫掺杂光催化剂

以脱硫废液为主要盐分提取硫氰酸铵(NH 4 SCN),通过热解合成光催化剂石墨碳氮化物(gC 3 N 4)。gC 3 N 4光催化剂通过在乙醇中加入不同量的七水硫酸亚铁进行改性,导致材料的Fe掺杂和一定程度的S掺杂。根据表征结果,改性样品eg-C 3 N 4 /FeSO 4-10% 具有优异的光催化效率,表现出最高的比表面积和孔体积,结晶度差,样品聚合度好。修饰后的样品结构中存在更多的 C 缺陷空位,增加了三嗪环结构中 C 和 N 原子周围的电子密度,成为电子捕获中心。同时,乙醇溶剂的存在促进了大量孤对电子与金属Fe离子之间形成更多的Fe-N配位键。此外,随着S元素掺杂量的增加,引入了新的杂质能级,样品的带隙宽度变窄。改性样品的表面结构和能带结构的变化导致载流子复合率显着降低,进一步促进了更多活性氧基团的产生。在有机污染物罗丹明B(RhB)降解过程中,可见光照射60 min后降解率迅速达到98%,比gC高78%3 N 4,同时将光催化反应速率常数从 0.007/min 增加到 0.305/min。同时,样品eg-C 3 N 4 /FeSO 4 -10% 在空气污染的NO x去除过程中也表现出优异的光催化活性。与原gC 3 N 4 相比,NO去除率从64%提高到75%,有害中间体NO 2的产生量从0.15mg/m 3降低到0.08mg/m 3

更新日期:2021-06-07
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