石墨烯纳米孔局部电场增强效应降解全氟有机污染物研究

Perfluorinated compounds (PFCs) cause a great threat to the environment and human health. Due to the high stability, PFOA is difficult to degrade through traditional methods. The degradation research of perfluorooctanoic acid (PFOA), a typical PFC, is of great theoretical significance and application guidance for PFCs treatment. Electrochemical oxidation is green, efficient and promising for PFOA degradation. The electrochemical degradation of PFOA is a combination of direct electrochemical oxidation (or direct electron transfer, DET) and indirect electrochemical oxidation (oxidation of harmful by-products from DET by free radicals from water electrolysis). DET of PFOA needs high overpotential (> 3 V), while theoretical potential of water electrolysis is as low as 1.23 V. The practical working voltage is usually much higher than the potential of water electrolysis, leading to the overelectrolysis of water, which seriously affects the current efficiency. The present proposal plans to systematically investigate the effective control over physical and chemical properties of nanopores in the porous graphene, and reveals the influencing mechanism of the properties of graphene nanopores on the electrochemical behavior of PFOA. By combining the electric field enhancement effect and PFOA adsorption enrichment effect in micro area of graphene nanopores, DET could likely be confined within the graphene nanopores with local high voltage with optimized electrolyte conditions (e.g. pH) and electrolysis conditions (e.g. effective voltage), while water electrolysis mainly occurs on the graphene basal plane with relatively low potential. This strategy is expected to increase the current efficiency substantially, to provide new ideas for the electrochemical degradation of PFOA, and further to promote the practical application of graphene materials in the electrochemical advanced oxidation process for environmental remediation.

全氟化合物（PFCs）对环境和人类健康构成了极大威胁，典型PFCs全氟辛酸（PFOA）用量巨大，稳定性极高，一般方法难以降解，其降解研究具有重要的理论意义和应用价值。PFOA的电化学降解绿色有效，极具前景，其过程是直接电化学氧化（DET）和间接电化学氧化（即水电解产生自由基氧化DET副产物）的复合，而DET活化能很高，致使工作电压（＞3V）高于水电解电位（理论1.23V），造成水电解过度，严重影响电解效率及电流利用率。本项目拟探索多孔石墨烯孔道性质的有效控制途径，深入研究石墨烯纳米孔对PFOA降解行为的影响机理，结合石墨烯纳米孔对PFOA的局部吸附富集和对外施电压的微区增强，将DET和水电解析氧两个需要不同电压的过程在空间上加以分离，来强化PFOA电化学降解、提高电流利用率。该项目的成功实施，不仅为电化学降解PFOA提供了新思路，还可进一步拓展石墨烯材料在环境电化学领域的实际应用。

全氟化合物（PFCs）对环境和人类健康构成了极大威胁，典型PFCs全氟辛酸（PFOA）用量巨大，稳定性极高，一般方法难以降解，其降解研究具有重要的理论意义和应用价值。PFOA的电化学降解绿色有效，极具前景，其过程是直接电化学氧化（DET）和间接电化学氧化（即水电解产生自由基氧化DET副产物）的复合，而DET活化能很高，致使工作电压高于水电解电位，造成水电解过度，严重影响电解效率及电流利用率。石墨烯纳米筛具有对PFOA的局部吸附富集和对外施电压的微区增强作用，有望将DET和水电解析氧两个需要不同电压的过程在空间上加以分离，来强化PFOA电化学降解、提高电流利用率。本项目利用硫酸盐与石墨烯材料的固相热反应，开发了有效的石墨烯纳米筛制备技术，面内孔道可以在几个纳米到几十纳米调控，表面化学性质与电化学活性也可以在一定程度上加以调节。在小型电解池电解实验中，石墨烯纳米筛电极与传统电极相比展现出较好的PFOA电化学吸附和降解性能。研究对新型碳纳米材料在PFCs水污染修复方面有一定的指导意义和借鉴价值。此外，鉴于石墨烯纳米筛的制备成本仍然较高、且存在二次污染问题。本项目后期利用天然贝壳开发了两种制备生物质基碳纳米筛的方法，不仅开拓了二维纳米筛材料的制备与应用途径，也将为解决海洋渔业废弃物污染的环境问题提供一条新的思路。