Hoque Md Khairul, Behan James A, Stamatin Serban N, Zen Federico, Perova Tatiana S, Colavita Paula E
School of Chemistry, CRANN, AMBER Research Centres, Trinity College Dublin Dublin 2 Ireland
University of Bucharest, Faculty of Physics, 3Nano-SAE Research Centre 405 Atomistilor Str, Magurele 077125 Bucharest Romania.
RSC Adv. 2019 Jan 30;9(7):4063-4071. doi: 10.1039/c8ra10187f. eCollection 2019 Jan 25.
Nitrogen incorporated carbon materials play an important role in electrochemical energy conversion technologies from fuel cells to capacitive storage devices. This work investigates the effects of nitrogen incorporation on capacitance, work function and semiconductor properties of amorphous carbon thin film electrodes. Nitrogenated electrodes (a-C:N) electrodes were synthesized magnetron sputtering and characterized using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy (UPS), Raman spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). EIS was carried in both aqueous (0.1 M KCl) and organic (0.1 M TBAPF/acetonitrile) electrolytes to discriminate between pseudocapacitive contributions and changes to semiconductor properties of the materials arising from structural and chemical disruption of the graphitic carbon scaffold. Raman and UPS spectroscopy both suggest that nitrogen incorporation increases the metallic character of the disordered carbon matrix at low-intermediate concentrations, whereas further nitrogen incorporation results in significantly more defective carbon with small graphitic cluster size. EIS studies in 0.1 M KCl indicate that the capacitance of a-C:N electrodes increases relative to nitrogen-free a-C electrodes due to a combination of microroughness and pseudocapacitive contributions in parallel to those of the double layer capacitance. Results in 0.1 M TBAPF in acetonitrile which are dominated by the interfacial capacitance, show that initial nitrogen incorporation into the disordered carbon scaffold compensates for p-type properties in the disordered carbon matrix, resulting in an increase in metallic character. Greater levels of nitrogenation, are instead disruptive and increase defect density while decreasing the double layer capacitance.
含氮碳材料在从燃料电池到电容存储设备的电化学能量转换技术中发挥着重要作用。这项工作研究了氮的掺入对非晶碳薄膜电极的电容、功函数和半导体性能的影响。采用磁控溅射法合成了含氮电极（a-C:N），并使用X射线光电子能谱、紫外光电子能谱（UPS）、拉曼光谱、循环伏安法（CV）和电化学阻抗谱（EIS）对其进行了表征。在水性（0.1 M KCl）和有机（0.1 M TBAPF/乙腈）电解质中进行EIS测量，以区分赝电容贡献以及由于石墨碳支架的结构和化学破坏而导致的材料半导体性能变化。拉曼光谱和UPS光谱均表明，在低至中等浓度下，氮的掺入增加了无序碳基体的金属特性，而进一步掺入氮会导致具有更小石墨簇尺寸的碳缺陷显著增多。在0.1 M KCl中进行的EIS研究表明，由于微观粗糙度和赝电容贡献与双层电容贡献并行，a-C:N电极的电容相对于无氮a-C电极有所增加。在乙腈中0.1 M TBAPF的测量结果以界面电容为主，结果表明，最初将氮掺入无序碳支架可补偿无序碳基体中的p型特性，从而导致金属特性增加。相反，更高程度的氮化具有破坏性，会增加缺陷密度，同时降低双层电容。
