Single-crystalline Fe7S8/Fe3O4 coated zero-valent iron synthesized with vacuum chemical vapor deposition technique: Enhanced reductive, oxidative and photocatalytic activity for water purification
Single-crystalline Fe7S8/Fe3O4 coated zero-valent iron synthesized with vacuum chemical vapor deposition technique: Enhanced reductive, oxidative and photocatalytic activity for water purification
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采用真空化学气相沉积技术合成的单晶 Fe7S8/Fe3O4 涂层零价铁：增强水净化的还原、氧化和光催化活性
DOI：
10.1016/j.jhazmat.2020.123442
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发表时间：
2021-01-05
影响因子：
13.6
通讯作者：
Cai, Yaqi
中科院分区：
文献类型：
--
作者：
Niu, Hongyun;Yang, Yongliang;Cai, Yaqi
采用真空化学气相沉积（CVD）技术制备了核壳结构的Fe_7S_8/Fe_3 O_4包覆α-Fe单晶混合材料（Fe_7S_8/Fe_3 O_4@Fe）。CVD过程触发商业Fe纳米颗粒表面上自然形成的Fe 3 O 4层从非晶相转化为单晶相。Fe_7S_8/Fe_3 O_4涂层提高了氧与靶材的表面亲合力，使电子从Fe核迅速转移到靶材，从而降低了Fe_7S_8/Fe_3 O_4@Fe表面的水分解，赋予了Fe_7S_8/Fe_3 O_4@Fe超强的还原性，提高了在不同条件下的氧化能力。与水热法或溶剂热法制备的硫化ZVI不同，Fe 7S 8涂层表面S-2（-）/S-2（2-）氧化释放H+，而不是水分解，从而减缓了反应液pH值的升高。Fe_7S_8与Fe_3O_4和α-Fe的协同作用不仅提高了Fe_7S_8涂层的抗氧化能力，而且还使其带隙变宽。通过使用Fe 7S 8/Fe3O4@Fe纳米杂化物作为光催化剂，光照射加速有机污染物的降解，并提高矿化效率。Fe 7S 8/Fe3O4@Fe在曝气、可见光和太阳光照射下处理城市污水处理厂的进水，均表现出良好的性能。
Well-defined core/shell type single crystalline Fe7S8/Fe3O4 coated alpha-Fe hybrids (Fe7S8/Fe3O4@Fe) are synthesized with vacuum chemical vapor deposition (CVD) technique. The CVD process triggers conversion of naturally formed Fe3O4 layer on the surface of commercial Fe nanoparticles from amorphous into single crystalline phase. The Fe7S8/Fe3O4 coat promotes the surface affinity of dissolved oxygen and targets and rapidly transfers electrons from the Fe core to targets, which decreases water splitting on Fe7S8/Fe3O4@Fe surface and endows Fe7S8/Fe3O4@Fe with ultra-strong reducibility and improved oxidative ability under different conditions. Different with the sulfurized ZVI prepared with hydrothermal or solvothermal method, the increase of reaction solution pH is retarded due to the relieved water splitting instead of releasing H+ via oxidation of S-2(-)/S-2(2-) on the Fe7S8 coat. The cooperation of Fe7S8 with Fe3O4 and alpha-Fe not only improves the anti-oxidation ability of Fe7S8 coating but also broadens its band gap. By using Fe7S8/Fe3O4@Fe nanohybrids as photocatalysts, light irradiation accelerates the degradation of organic pollutants combined with enhanced mineralization efficiency. The Fe7S8/Fe3O4@Fe exhibits good performance when it is utilized to treat the influent from a municipal sewage treatment plant upon air aeration or under visible light and solar light irradiation.