Preparation and catalytic studies of pyrrole-doped carbon black oxide cathode materials for oxygen reduction reactions
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摘要: 氧還原反應(ORR) 是堿性燃料電池和金屬-空氣電池的重要陰極反應.由于常見的鉑基氧陰極材料存在價格昂貴、穩定性較低等問題, 因此, 開發低成本、高效率的非貴金屬基氧陰極材料具有重要的研究意義和應用價值.氮摻雜碳材料是目前氧陰極材料研究的熱點, 炭黑中碳原子的排列方式類似于石墨, 由于其價格低廉、來源廣泛, 在碳材料的研究中具有獨特的優勢.本文基于炭黑, 采用化學法制備了氮摻雜炭黑氧陰極材料, 研究了其氧還原反應催化活性, 并進行了相關表征.結果顯示炭黑-吡咯復合材料具有極好的氧還原反應活性, 700℃熱處理后性能最優, 在1 mol·L-1KOH中其起峰電位約為0. 9 V, 極限擴散電流密度為2. 6 m A·cm-2, 轉移電子數高于3. 5, 這些特性使得這類材料具有廣闊的應用前景.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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Key words:
- oxygen reduction reaction /
- cathode material /
- nitrogen doping /
- carbon material
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圖 4 rCBO和rCBO-Pyrrole的比表面積測試曲線. (a) rCBO的等溫吸附曲線; (b) rCBO-Pyrrole的等溫吸附曲線; (c) rCBO的孔徑分布曲線; (d) rCBO-Pyrrole的孔徑分布曲線
Figure 4. BET curves of rCBO and rCBO-Pyrrole: (a) N2sorption isotherm of rCBO; (b) N2sorption isotherm of rCBO-Pyrrole; (c) pore size distri-bution of rCBO; (d) pore size distribution of rCBO-Pyrrole
表 1 實驗儀器
Table 1. Apparatus
儀器 型號 生產廠家 電子天平 AL204 梅特勒-托利多儀器(上海)公司 磁力加熱攪拌器 78-1 江蘇省金壇市榮華儀器制造有限公司 高速離心機 CT14D 上海天美科學儀器有限公司 電熱恒溫鼓風干燥箱 DHG-9076A 上海浦東榮豐科學儀器有限公司 恒溫加熱磁力攪拌器 DF-101K 鄭州恒巖儀器有限公司 超聲波清洗器 KQ-100KDE 昆山市超聲儀器有限公司 紫外可見光分光光度計 UV2600 北京博遠祥德科學儀器有限公司 電化學工作站 CHI 750D 上海辰華儀器公司 旋轉圓盤電極附件 RDE 710 Gamary 表 2 化學試劑
Table 2. Chemical reagents
試劑 生產廠家 炭黑 天津金秋實化工有限公司 硝酸鈉 天津市津科精細化工研究所 高錳酸鉀 北京化工廠 30%(質量分數)過氧化氫 北京化工廠 硫酸 北京化工廠 鹽酸 北京化工廠 碳酸氫鈉 北京化工廠 氫氧化鉀 北京化工廠 EDTA二鈉鹽 廣東市金華大化學試劑有限公司 丙三醇 北京化工廠 異丙醇 北京化工廠 Nafion Alfa Aesar 氨水 北京化工廠 吡啶 Alfa Aesar 吡咯 Alfa Aesar 三聚氰胺 北京化工廠 六次甲基四胺 北京化工廠 乙醇 北京化工廠 259luxu-164 -
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