Experimental and theoretical identifications of durable Fe–Nx configurations embedded in graphitic carbon nitride for uranium photoreduction. Issue 5 (October 2022)

• Record Type: Journal Article
• Authors: Hong, Jiahui; Ma, Ran; Wu, Yunchao; Liu, Yang; Wen, Tao; Zhang, Sai; Wang, Suhua; Wang, Xiangke; Ai, Yuejie
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 5(2022)
• Publication Date: 2022-10
• Subjects: Photocatalytic reduction -- G-C3N4 -- Fe-N configurations -- Uranium -- DFT calculations; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.108374
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: Uranium extraction from seawater has attracted increasing attentions for nuclear raw material to support the sustainable development of nuclear power plants. However, it is still a grand challenge to overcome the high salinity background and ultra-low uranyl concentration. Herein, we successfully achieved Fe-N x configurations embedded in graphitic carbon nitride (FeN x /g-C3 N4 ) through one-step pyrolysis strategy. Our density function theory (DFT) calculations reveal that the site-isolated FeN x centers are the predominant binding sites for U(VI) species, and visible-light photoexcitation can effectively facilitate the electron escaping from FeN x /g-C3 N4 surface relative to pure g-C3 N4, which is consequently favorable for electron transfer in the photoreduction conversion of U(VI) to U(IV). Consistent with the theoretical results, the obtained FeN x /g-C3 N4 ( w (Fe-MOFs): w (g-C3 N4 ) = 2:1) delivers remarkably higher reduction activity with the conversion efficiency of 99 % and rate constant of 0.091 min −1, almost 9.1 and 12.5 times faster than those of g-C3 N4 and TiO2 catalysts, respectively. The results showed that the introduction of FeN x could effectively activate g-C3 N4 catalysts for significantly broadening the absorption range of g-C3 N4 to visible light, inhibiting recombination of the photogenerated e - -h + and further facilitating the reduction of U(VI). It is worthwhile to mention that FeN x /g-C3 N4 maintains a high level for the extraction of uranium from seawater, endowing the metal-N configurations embedded g-C3 N4 as a kind of promising candidate for the sustainable conversion of radionuclides. Graphical Abstract: ga1 Highlight: FeNx/g-C3N4 was synthesized via one-step pyrolysis strategy. FeNx/g-C3N4 with outstanding performance for photocatalytic reduction uranium. DFT calculations reveal that the FeNx sites are the predominant binding sites. FeNx/g-C3N4 can effectively extract U(VI) from seawater with high electrolyte ions.