配位负载法制备CoS2/AOCF复合材料及电催化析氢性能

Synthesis of CoS2/amidoximated polyacrylonitrile (AOCF) composites by the method of coordination loading and its electrocatalytic hydrogen-evolution activity

摘要:

以硫酸钴、硫代硫酸钠、硫和偕胺肟化聚丙烯腈纤维(AOCF)为原料，采用配位负载法制备了CoS2/AOCF复合材料，通过设计偕胺肟化聚丙烯腈高分子链上的—OH和—NH2基团与Co(Ⅱ)配位作用，极大提高了活性组分CoS2的比表面积，改变了活性组分的晶体结构，增大了有效活性位点的数量。采用SEM、XRD、TEM、XPS和BET对CoS2/AOCF进行物相分析和形貌表征，并对CoS2/AOCF复合材料进行电催化析氢性能测试。结果表明：CoS2/AOCF在10 mA/cm2的电流密度下过电势为92 mV，Tafel斜率仅为43 mV/dec，具有良好的析氢稳定性，展现了优异的电化学性能。

Abstract:

The CoS2/AOCF composites was prepared by the method of coordination loading with CoSO4, Na2S2O3, S and AOCF as raw materials. By making the lone pair electrons O, N of —OH and —NH2 groups on amidoximated polyacrylonitrile polymer chain in coordination with Co(Ⅱ), the specific surface area of the active component CoS2 was greatly improved and the crystal structure of the active component was changed, increasing the number of active sites. The phase analysis and morphological characterization of the CoS2/AOCF composites were carried out by means of SEM, XRD, TEM, XPS and BET. Then the CoS2/AOCF composites were tested for electrocatalytic hydrogen evolution performance. The growth mechanism of "dissolution-coordination-recrystallization" of the composite surface morphology was proposed. The results show that cobalt ion have empty d orbitals and free d electrons, which can easily accept the electron pair of ligands, and the d electrons are fed back to the ligands, which greatly increases the stability of the compound. When the CoS2/AOCF composites are directly used as a binder-free electrocatalyst coating, the design of coordination covalent bond makes the bonding between the active components of electrocatalyst layer and the glassy carbon substrate stronger. On the one hand, it not only avoids the degradation of catalytic performance caused by using binders, but also improves the dispersity of CoS2 particles. On the other hand, CoS2/AOCF composites can expose more active sites, which is beneficial to the release of hydrogen on the electrode surface. The overpotential of CoS2/AOCF is 92 mV at a current density of 10 mA/cm2, and the Tafel slope is only 43 mV/dec. It has good hydrogen evolution stability and exhibits excellent electrochemical performance. This simple and low-cost post-synthesis strategy can be extended to the preparation of various functional electrocatalysts. The present work is expected to contribute to the practical application of sulfide electrocatalysts.