National Fundamental Research Laboratory of New Hazardous Chemicals Assessment & Accident Analysis, and ‡Institute of Applied Electrochemistry, Beijing University of Chemical Technology , 100029 Beijing, P. R. China.
ACS Appl Mater Interfaces. 2017 Jun 21;9(24):20963-20973. doi: 10.1021/acsami.7b02306. Epub 2017 Jun 12.
Hierarchical porous Fe/N/S-doped carbon with a high content of graphitic nitrogen (FeNS/HPC) has been successfully synthesized by a facile dual-template method. FeNS/HPC shows not only macropores resulting from the dissolution of the SiO template, but abundant mesopores were also obtained after removing the in situ generated FeO nanoparticles on the ultrathin (∼4 nm) carbon shell of the macropores. Moreover, micropores are produced during the thermal pyrolysis of the carbon precursors. With respect to the electrochemical performance in the oxygen reduction reaction (ORR), FeNS/HPC not only exceeds other prepared porous carbon materials completely but also shows higher onset potential (0.97 vs 0.93 V), half-wave potentials (0.87 vs 0.83 V), and diffusion current density (5.5 vs 5.3 mA cm) than those of Pt/C. Furthermore, FeNS/HPC also exhibits outstanding stability and methanol tolerance, making it a competent candidate for ORR. The following aspects contribute to its excellent ORR performance. (1) High content of graphitic N (5.1%) and codoping of pyridinic N species, thiophene-S, FeN, and graphitic carbon-encapsulated iron nanoparticles, providing highly active sites. (2) The hierarchical porous mesh structure with micro-, meso-, and macroporosity, accelerating the mass transfer and facilitating full utilization of the active sites. (3) The high specific surface area (1148 m g) of the graphitic carbon shell, assuring a large interface and rapid electron conduction for ORR.
通过简便的双模板法成功合成了具有高石墨氮含量的分级多孔 Fe/N/S 掺杂碳（FeNS/HPC）。FeNS/HPC 不仅具有源自 SiO2 模板溶解的大孔，而且在去除大孔的超薄（∼4nm）碳壳上原位生成的 FeO 纳米颗粒后，还获得了丰富的介孔。此外，在碳前体的热解过程中产生了微孔。就其在氧还原反应（ORR）中的电化学性能而言，FeNS/HPC 不仅完全超过了其他制备的多孔碳材料，而且还表现出更高的起始电位（0.97 对 0.93V）、半波电位（0.87 对 0.83V）和扩散电流密度（5.5 对 5.3mA cm）。此外，FeNS/HPC 还表现出出色的稳定性和甲醇耐受性，使其成为 ORR 的有竞争力的候选者。以下几个方面有助于其出色的 ORR 性能。（1）高含量的石墨 N（5.1%）和吡啶 N 物种、噻吩-S、FeN 和石墨碳包封的铁纳米粒子的共掺杂，提供了高活性位点。（2）具有微孔、介孔和大孔的分级多孔网格结构，加速了质量传递并促进了活性位点的充分利用。（3）石墨碳壳的高比表面积（1148m2g）确保了大的界面和 ORR 的快速电子传导。
