Tunable mesoporous g-C3N4 nanosheets as a metal-free catalyst for enhanced visible-light-driven photocatalytic reduction of U(VI)
Tunable mesoporous g-C3N4 nanosheets as a metal-free catalyst for enhanced visible-light-driven photocatalytic reduction of U(VI)
复制标题
可调谐介孔 g-C3N4 纳米片作为无金属催化剂，用于增强可见光驱动的 U(VI) 光催化还原
DOI：
10.1016/j.cej.2019.123193
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发表时间：
2019
影响因子：
15.1
通讯作者：
Qiaohui Fan
中科院分区：
文献类型：
--
作者：
Jingjing Wang;Yun Wang;Wei Wang;Zhe Ding;Rongyue Geng;Ping Li;Duoqiang Pan;Jianjun Liang;Haibo Qin;Qiaohui Fan
虽然光催化还原已被证明是一种绿色、高效和经济的从水中提取铀（VI）的策略，但它面临着一些挑战，例如低量子转换效率和利用太阳光。本文通过引入比例可调的介孔分子筛，对g-C3 N4的光催化效率进行了调控。所制备的介孔g-C3 N4样品（MCNr，r表示合成过程中初始硅/氰胺质量比）具有更高的比表面积和更大的孔容。与纯的g-C3 N4（BCN）相比，MCNR的光利用率和光生载流子分离效率均显著提高。在可见光下，MCNR对U（VI）的光催化还原具有较好的效果。MCN1.0的光催化性能最好，是BCN的6.75倍。透射电子显微镜（TEM）和X射线衍射（XRD）均证实了光照后在MCN1.0表面生成了UO 2。X射线光电子能谱（XPS）和扩展X射线吸收精细结构（EXAFS）进一步揭示了UO 2在光催化过程中的再氧化过程。MCN1.0对铀的萃取能力可达2990 mg/g，且在暴露于空气中后，用0.01 mol/L Na 2CO 3溶液可将沉积的UO 2轻松洗脱，具有较高的重复利用性能。在共存离子存在下，U（VI）的光催化还原仍然具有较高的选择性。
Although photocatalytic reduction has been proven to be a green, efficient, and economical strategy for uranium(VI) extraction from water, it faces several challenges, such as low quantum conversion efficiency and utilization of sunlight. In this work, the photocatalytic efficiency of g-C3N4was tuned by introducing proportionally-adjustable mesoporous. The prepared mesoporous g-C3N4samples (MCNr,rrepresents the initial silica/cyanamide mass ratios during synthesis) exhibited higher surface area and larger pore volume. Compared with pristine g-C3N4(BCN), both light utilization and photo-generated carrier separation efficiency were significantly improved for MCNr. MCNrshowed an enhanced photocatalytic performance for the reduction of U(VI) under visible light. The optimum photocatalytic performance was achieved for MCN1.0, which was 6.75 times higher than that of BCN. Both transmission electron microscopy (TEM) and X-ray diffraction (XRD) have confirmed the formation of UO2on MCN1.0surface after light irradiation. X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) further revealed the re-oxidation of UO2during the photocatalytic process. A high uranium extraction capacity (~2990 mg/g) could be achieved by MCN1.0, and the deposited UO2could be easily eluted by 0.01 mol/L Na2CO3solution after exposure to air, showing high reuse performance. In the presence of co-existing ions, the photocatalytic reduction of U(VI) remained a high selectivity.