Zhan Cheng, Zhang Yu, Cummings Peter T, Jiang De-en
Department of Chemistry, University of California, Riverside, CA 92521, USA.
Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA.
Phys Chem Chem Phys. 2016 Feb 14;18(6):4668-74. doi: 10.1039/c5cp06952a.
Recent experiments have shown that nitrogen doping enhances capacitance in carbon electrode supercapacitors. However, a detailed study of the effect of N-doping on capacitance is still lacking. In this paper, we study the doping concentration and the configuration effect on the electric double-layer (EDL) capacitance, quantum capacitance, and total capacitance. It is found that pyridinic and graphitic nitrogens can increase the total capacitance by increasing quantum capacitance, but pyrrolic configuration limits the total capacitance due to its much lower quantum capacitance than the other two configurations. We also find that, unlike the graphitic and pyridinic nitrogens, the pyrrolic configuration's quantum capacitance does not depend on the nitrogen concentration, which may explain why some capacitance versus voltage measurements of N-doped graphene exhibit a V-shaped curve similar to that of undoped graphene. Our investigation provides a deeper understanding of the capacitance enhancement of the N-doping effect in carbon electrodes and suggests a potentially effective way to optimize the capacitance by controlling the type of N-doping.
近期实验表明，氮掺杂可提高碳电极超级电容器的电容。然而，目前仍缺乏对氮掺杂对电容影响的详细研究。在本文中，我们研究了掺杂浓度以及构型对双电层（EDL）电容、量子电容和总电容的影响。研究发现，吡啶型氮和石墨型氮可通过增加量子电容来提高总电容，但吡咯型构型因其量子电容远低于其他两种构型而限制了总电容。我们还发现，与石墨型氮和吡啶型氮不同，吡咯型构型的量子电容不依赖于氮浓度，这或许可以解释为什么一些氮掺杂石墨烯的电容与电压测量结果呈现出与未掺杂石墨烯类似的V形曲线。我们的研究为深入理解碳电极中氮掺杂效应导致的电容增强提供了依据，并提出了一种通过控制氮掺杂类型来优化电容的潜在有效方法。
