Institute of Oceanic and Environmental Chemical Engineering, State Key Lab Breeding Base of Green Chemical Synthesis Technology , Zhejiang University of Technology , Hangzhou 310014 , China.
Department of Mechanical Engineering, College of Engineering , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States.
ACS Appl Mater Interfaces. 2019 Jan 30;11(4):3925-3936. doi: 10.1021/acsami.8b18704. Epub 2019 Jan 16.
A facile postsynthetic amidoxime modification method was reported on the preparation of transition-metal ions (Mn, Fe, and Co)-polyacrylonitrile (PAN) polymeric beads complex as reusable catalysts for efficient and stable heterogeneous electro-Fenton oxidation. Through one-step phase inversion, low-cost and chemically resistant polymeric PAN beads were fabricated on a large scale with controllable sizes and abundant porous structure. The postfunctionalization strategy led more active sites to be uniformly distributed into modified PAN beads owing to the favorable channel confined effect and chelate coordination. Compared with pure PAN beads, the modified composite catalysts exhibited remarkably higher activity and stability in electro-Fenton oxidation over wide pH range of 3-10 without any addition of HO. By analysis, the grafted amidoxime group was extremely beneficial for improving metal loading and binding force between active sites and organic supports, which accelerated the active sites autocatalytic cycle to promote HO activation by means of excited electron transfer from composites' functional groups. The catalytic activity of Mn-amidoximated PAN evaluated by the turnover frequency was 15 times more than that of traditional iron oxide and very competitive to the reported metal-organic framework-based composites. Moreover, a strong metal and polymeric support interaction significantly enhanced the stabilization of active sites dispersed in porous matrix and solved the ever-present problem of metallic ions leaching to the greatest extent. The scalable introduction of functionalities into sophisticated structures after host framework synthesis will bring valuable insights to develop highly efficient and stable heterogeneous catalysts for green electrochemical oxidation in practical application.
报道了一种简便的后合成偕胺肟修饰方法，用于制备过渡金属离子（Mn、Fe 和 Co）-聚丙烯腈（PAN）聚合物珠复合物，作为高效稳定的非均相电芬顿氧化的可重复使用催化剂。通过一步相转化，可大规模制备具有可控尺寸和丰富多孔结构的低成本、耐化学试剂的 PAN 聚合物珠。后功能化策略导致更多的活性位点由于有利的通道限制效应和螯合配位而均匀分布在改性的 PAN 珠中。与纯 PAN 珠相比，在没有任何 HO 添加的情况下，在 pH 值为 3-10 的宽范围内，改性复合催化剂在电芬顿氧化中表现出显著更高的活性和稳定性。通过分析，接枝的偕胺肟基团非常有利于提高金属负载和活性位点与有机载体之间的结合力，这加速了活性位点的自催化循环，通过复合材料官能团的受激电子转移来促进 HO 的活化。通过周转率评估的 Mn-偕胺肟化 PAN 的催化活性比传统的氧化铁高 15 倍，并且与报道的基于金属有机骨架的复合材料具有很强的竞争力。此外，金属和聚合物载体之间的强相互作用极大地增强了分散在多孔基质中的活性位点的稳定性，并在最大程度上解决了金属离子浸出的长期存在问题。在主框架合成后可扩展地将功能引入复杂结构中，将为实际应用中绿色电化学氧化的高效稳定非均相催化剂的开发提供有价值的见解。
