A novel approach to introduce catalytic sites to carbon and graphite felts in order to improve electrode activity and investigate the effectiveness of specific active sites for the vanadium flow battery (VFB) has been achieved via ion beam implantation. Here, both N and Ne implantation is used to show that the positive vanadium (VO/VO) redox reaction preferentially occurs at the introduced defect sites, and not nitrogen-containing groups. This is shown through short charge and discharge tests and electrochemical impedance spectroscopy, with the electrodes characterised via X-ray photoelectron and Raman spectroscopies. Lower implantation fluences (1 × 10–4 × 10 ion cm) were shown to improve the pristine electrodes due to the formation of defect sites. However, implantation at higher fluences (above 4 × 10 ion cm) resulted in a decrease in defect density, and a layer of amorphous carbon at the electrode surface was thought to hinder the redox reaction due to lower surface conductivity and less available active sites. This new approach of felt electrode modification shows that nitrogen-containing groups are not necessary for the positive vanadium redox reaction and shows the importance of defect engineering of electrodes for the VFB.

中文翻译：

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钒液流电池毛毡电极的新型离子束注入：缺陷与氮基团在 VO2+/VO2+ 氧化还原反应中的作用


通过离子束注入实现了一种在碳和石墨毡中引入催化位点的新方法，以提高电极活性并研究钒液流电池（VFB）特定活性位点的有效性。此处，N 和 Ne 注入均用于表明正钒 (VO/VO) 氧化还原反应优先发生在引入的缺陷位点，而不是含氮基团。这通过短充放电测试和电化学阻抗谱得到证明，电极通过 X 射线光电子和拉曼光谱进行表征。由于缺陷位点的形成，较低的注入注量（1 × 10–4 × 10 离子厘米）可以改善原始电极。然而，较高注量（高于 4 × 10 ion cm）的注入会导致缺陷密度降低，并且电极表面的一层无定形碳被认为会由于较低的表面电导率和较少的可用活性位点而阻碍氧化还原反应。这种毡电极改性的新方法表明，含氮基团对于钒的正氧化还原反应不是必需的，并且显示了电极缺陷工程对于 VFB 的重要性。