Improvement of Oxygen-Depolarized Cathodes in Highly Alkaline Media by Electrospinning of Poly(vinylidene fluoride) Barrier Layers

Oxygen-depolarized cathodes (ODC) were developed for chlor-alkali electrolysis to replace the hydrogen evolution reaction (HER) by the oxygen reduction reaction (ORR) providing electrical energy savings up to 30% under industrially relevant conditions. These electrodes consist of micro sized silver grains and polytetrafluoroethylene, forming a homogeneous electrode structure. In this work, we report on the modification of ODCs by implementing an electrospun layer of hydrophobic poly(vinylidene fluoride) (PVDF) into the ODC structure, leading to a significantly enhanced ORR performance. The modified electrodes are physically characterized by liquid flow porometry, contact angle measurements and scanning electron microscopy. Electrochemical characterization is performed by linear sweep voltammetry and chronopotentiometry. The overpotential for ORR at application near conditions could be reduced by up to 75mV at 4kAm(-2) and 135mV at a higher current density of 9.5kAm(-2). Consequently, we propose that modifying ODCs by electrospinning is an effective and cost-efficient way to further reduce the energy demand of the ORR in highly alkaline media.

氧去极化阴极（ODC）被开发用于氯碱电解，以氧还原反应（ORR）代替氢释放反应（HER），在与工业相关的条件下可节省多达30％的电能。这些电极由微米尺寸的银颗粒和聚四氟乙烯组成，形成均匀的电极结构。在这项工作中，我们报告了通过在ODC结构中实现疏水性聚偏二氟乙烯（PVDF）的静电纺丝层而对ODC进行的改性，从而显着提高了ORR性能。修饰的电极通过液体流动孔隙率法，接触角测量和扫描电子显微镜在物理上进行表征。电化学表征通过线性扫描伏安法和计时电位法进行。在4kAm（-2）附近应用时，ORR的过电势可以降低高达75mV，在9.5kAm（-2）更高的电流密度下可以降低135mV。因此，我们提出通过静电纺丝修饰ODC是一种进一步降低高碱性介质中ORR能量需求的有效且具有成本效益的方法。

Published: 2020

Journal ：ChemElectroChem

Impact Factor：4.085

Paper link: https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/celc.201902115