Fe3+ doping promoted N2 photofixation ability of honeycombed graphitic carbon nitride: The experimental and density functional theory simulation analysis
Fe3+ doping promoted N2 photofixation ability of honeycombed graphitic carbon nitride: The experimental and density functional theory simulation analysis
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DOI：
10.1016/j.apcatb.2016.08.002
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发表时间：
2017-02-01
影响因子：
22.1
通讯作者：
Wu, Guang
中科院分区：
文献类型：
--
作者：
Hu, Shaozheng;Chen, Xin;Wu, Guang
本工作合成了具有优异的N-2光固定能力的蜂窝状铁掺杂石墨化碳氮化物。表征结果表明，Fe3+通过配位的Fe-N键稳定在富电子的g-C3N4中，并嵌入间隙位置。Fe3+中心可以化学吸附和激活N-2分子，然后将光生电子从g-C3N4转移到吸附的N-2分子上。Fe0.05-CN的NH4+生成率最高，约为纯g-C3N4的13.5倍。密度泛函理论模拟证实了Fe3+的N-2活化效应，这是由于Fe3+具有较高的吸附能和延长的N当量N键所致。电荷密度差结果证实了电子从Fe3+掺杂位置向N-2分子的转移过程。DOS结果表明，当N-2吸附在Fe3+掺杂位上时，氮原子中的sigma(G)2p轨道(HOMO)的电子明显离域，导致其轨道能量几乎与pIg*2p轨道(LUMO)的电子能量相连接，这证实了Fe3+掺杂位置能够有效地激活N-2分子。当N-2吸附在Fe3+掺杂位上时，N的Mulliken电荷为-3.1，这表明N-2分子被大量的电子所富集，这有利于LE攻击形成NH4。(C)2016爱思唯尔B.V.保留所有权利。
Honeycombed iron doped graphitic carbon nitride with outstanding N-2 photofixation ability is synthesized in this work. Characterization results indicate that Fe3+ inserts at the interstitial position and is stabilized in the electron-rich g-C3N4 through the coordinative Fe-N bonds. Fe3+ sites can chemisorb and activate N-2 molecules, then transfer the photogenerated electrons from the g-C3N4 to adsorbed N-2 molecules. Fe0.05-CN displays the highest NH4+ generation rate, which is approximately 13.5-fold higher than that of neat g-C3N4. Density functional theory simulations prove the N-2 activation effect of Fe3+ sites due to the high adsorption energy and prolonged N equivalent to N bond. Charge density difference result confirms the electrons transfer process from the Fe3+ doping sites to N-2 molecule. DOS results indicate that the electrons of sigma(g)2p orbital (HOMO) in nitrogen atom is delocalized significantly when N-2 adsorbed on Fe3+ doping sites, leading to its orbital energy almost connects to that of pi g*2p orbital (LUMO), which confirming that Fe3+ doping sites can activate the N-2 molecule effectively. The Mulliken charge of nitrogen is -3.1 when the N-2 adsorbed on Fe3+ doping sites, indicating that N-2 molecule is enriched by large number of electrons, which is beneficial to the le attack to form NH4. (C) 2016 Elsevier B.V. All rights reserved.