卟啉-硫醚基共价有机框架材料用于氧还原反应电催化剂

Porphyrin-Sulfide-Based Covalent Organic Frameworks as Oxygen Reduction Reaction Electrocatalysts

氧还原反应(ORR)是能进行能量存储的核心电化学过程。由于它的动力学速率缓慢,因此亟需制备出高活性的电催化剂来促进这一反应的速率。二维共价有机框架材料(2D COFs)的π-π堆积结构可赋予骨架高导电率,并且一维有序的孔道有利于促进中间反应体传输。因此,其在可再生能源领域中具有良好的应用前景,并有望作为能量存储与转化的强大催化平台。本文通过向2D COFs中引入金属卟啉单元及硫醚单元成功制备了两个2D COFs(JUC-600和JUC-601)。通过多种表征手段证明,这两个2D COFs均具有AA堆积的sql拓扑结构。通过电化学测试表明,Co^(2+)配位的JUC-601具有更正的ORR起始电势(0.825 V)和半波电势(0.7 V)、更高的活性表面积(7.8 mF/cm^(2)),更低的Tafel斜率(58 mV/dec)。这主要是由于JUC-601的高比表面积和高孔隙率使得中间产物能更易在COFs的表面和孔道中接触和传输。此外,Co^(2+)-卟啉单元以及硫醚单元的存在使其骨架整体的电子结构发生了变化,更有利于电子转移。这一工作不仅开发了新的二维卟啉-硫醚基COFs材料,同时也拓展了2D COFs材料在电催化领域的应用。

The oxygen reduction reaction is the core electrochemical process for energy storage. Because of its slow kinetic rate,it is urgent to prepare electrocatalysts with high activity to promote the rate of this reaction. The π-π stacking structure of two-dimensional covalent organic frameworks(2D COFs)can endow the framework with high conductivity,and the one-dimensional ordered pores are beneficial to promote the transport of intermediate reactants. Therefore,it has good application prospects in the field of renewable energy and serves as a powerful catalytic platform for energy storage and conversion. Herein,we successfully prepare two 2D COFs(JUC-600 and JUC-601)by introducing metalloporphyrin and thioethers units into 2D COFs. The results suggest that two COFs have AA stacked sql topology. Electrochemical tests show that the Co^(2+)coordinated JUC-601 has a higher starting potential(0. 825 V)and half-wave potential(0. 7 V),a larger active surface area(7. 8 mF/cm^(2)),and a lower Tafel slope(58 mV/dec). We believe that this is due to the high specific surface area and high porosity of JUC-601,which makes the intermediate products easier to contact and transport on the surface and pores of COFs. In addition,the presence of Co^(2+)-porphyrin units and thioether units changes the electronic structure of the entire skeleton,which is more conducive to electron transfer. This work not only develops new 2D porphyrin-thioether-based COF materials,but also expands the application of COFs in the field of electrocatalysis.