吡咯/炭黑氧化物复合氧阴极材料的制备及催化性能

Preparation and catalytic studies of pyrrole-doped carbon black oxide cathode materials for oxygen reduction reactions

  • 摘要: 氧还原反应(ORR) 是碱性燃料电池和金属-空气电池的重要阴极反应.由于常见的铂基氧阴极材料存在价格昂贵、稳定性较低等问题, 因此, 开发低成本、高效率的非贵金属基氧阴极材料具有重要的研究意义和应用价值.氮掺杂碳材料是目前氧阴极材料研究的热点, 炭黑中碳原子的排列方式类似于石墨, 由于其价格低廉、来源广泛, 在碳材料的研究中具有独特的优势.本文基于炭黑, 采用化学法制备了氮掺杂炭黑氧阴极材料, 研究了其氧还原反应催化活性, 并进行了相关表征.结果显示炭黑-吡咯复合材料具有极好的氧还原反应活性, 700℃热处理后性能最优, 在1 mol·L-1KOH中其起峰电位约为0. 9 V, 极限扩散电流密度为2. 6 m A·cm-2, 转移电子数高于3. 5, 这些特性使得这类材料具有广阔的应用前景.

     

    Abstract: Oxygen reduction reaction (ORR) is an important cathode reaction for alkaline fuel and air-metal batteries. Because of the high cost and low stability of traditional Pt-based cathode materials for ORR, it is important to find an alternative cathode material of high performance and stability and low cost. Nitrogen-doped carbonaceous materials are currently of keen interest among those alternative oxygen cathode materials. The arrangement of carbon atoms in carbon black (CB) is similar to that of graphite, and it is wellknown that CB has a unique advantage over other carbon materials owing to its relatively low price and wide availability. Based on cheap carbon black, pyrrole-doped carbon black oxide (rCBO-Pyrrole) cathode materials were prepared using a facile synthesis method for this article, and their catalytic performances toward ORR were studied. The characterization of the catalysts was explored using a scanning electron microscope (SEM), a transmission electron microscope (TEM), ultraviolet-visible spectroscopy (UV-Vis), and Brunauer-Emmett-Teller (BET) specific surface area and X-ray photoelectron spectroscopy (XPS). The results of these analyses indicate that nitrogen is successfully doped in the rCBO-Pyrrole composite. BET results show that both rCBO and rCBO-Pyrrole have large specific surface areas, which increase significantly after pyrrole doping of carbon black. Further, the results of catalytic performances show that the rCBO-Pyrrole composite induces excellent catalytic activity toward ORR and exhibits the best performance after heat treatment at 700 ℃. In the electrolyte of KOH (1 mol·L-1), the onset potential of rCBO-Pyrrole is 0. 9 V vs RHE, and the limit diffusion current density of this catalyst is 2. 6 m A·cm-2. Moreover, the electron transfer number of ORR on rCBO-Pyrrole is higher than 3. 5, which indicates a preference for the four-electron reduction pathway. These characteristics and results demonstrate that this kind of material has broad potential applicability.

     

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