催化学报

催化学报 ›› 2023, Vol. 52: 228-238.DOI: 10.1016/S1872-2067(23)64495-X

• 论文 • 上一篇    下一篇

燃料电池多孔碳载体高石墨化的超快速碳热冲击策略

卢明佳, 梁乐程, 冯彬彬, 常译文, 黄志宏, 宋慧宇, 杜丽, 廖世军*(), 崔志明*()   

  1. 华南理工大学化学与化工学院, 广东省燃料电池技术重点实验室, 广东广州510641
  • 收稿日期:2023-06-17 接受日期:2023-07-30 出版日期:2023-09-18 发布日期:2023-09-25
  • 通讯作者: *电子信箱: zmcui@scut.edu.cn (崔志明),chsjliao@scut.edu.cn (廖世军).
  • 基金资助:
    国家自然科学基金(22072048);广东省科学技术部(2021A1515010128);广东省科学技术部(2022A0505050013)

Ultrafast carbothermal shock strategy enabled highly graphitic porous carbon supports for fuel cells

Mingjia Lu, Lecheng Liang, Binbin Feng, Yiwen Chang, Zhihong Huang, Huiyu Song, Li Du, Shijun Liao*(), Zhiming Cui*()   

  1. Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, Guangdong, China
  • Received:2023-06-17 Accepted:2023-07-30 Online:2023-09-18 Published:2023-09-25
  • Contact: *E-mail: zmcui@scut.edu.cn (Z. Cui),chsjliao@scut.edu.cn (S. Liao).
  • Supported by:
    National Natural Science Foundation of China(22072048);Guangdong Provincial Department of Science and Technology(2021A1515010128);Guangdong Provincial Department of Science and Technology(2022A0505050013)

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摘要：

质子交换膜燃料电池(PEMFC)具有能源转换效率高、清洁环保等优点, 是新能源技术的重要发展方向. 目前, 燃料电池中主要使用的电催化剂是碳载铂或铂合金, 碳载体不仅增强催化剂活性, 提高贵金属利用率, 而且对催化剂的耐久性起着至关重要的影响. 但常规的碳载体在燃料电池强腐蚀环境中容易发生腐蚀, 进而导致催化剂颗粒脱落和团聚, 活性衰减. 近年来, 研究发现提高碳载体石墨化程度有利于增强载体的耐腐蚀能力, 提高催化剂的稳定性. 常规的高温热处理难以大幅提高载体的石墨化, 且长时间的高温处理易导致原始碳结构的坍塌或转变以及比表面积显著下降. 因此, 迫切需要发展新的策略或技术经济、高效地提高碳载体的石墨化度, 并且保持碳载体原始结构和形貌.

本文提出了一种快速且低成本的碳热冲击方法, 用于多孔碳材料的石墨化处理, 包括碗状碳(BC)、空心碳球、ZIF-8衍生碳和商业炭黑等. 其中, 以碗状碳为研究对象, 即将碗状碳载体与石墨化催化剂氯化铁通过超声共混, 干燥后放入加热源碳毡中, 通过快速碳热冲击, 3 s内升温至1300 oC, 在该温度保温30 s后, 3 s降至室温, 最后酸洗得到高石墨化碗状碳. 作为对照, 含有氯化铁的碗状碳也在普通管式炉中石墨化处理. 采用X射线衍射(XRD)、Raman光谱、四探针电导率测试、氮气吸脱附曲线、扫描电镜(SEM)和透射电镜等表征手段对所得的石墨化碗状碳进行表征. 同时, 以碳热冲击所得的高石墨化碗状碳为载体合成了碳载的PtCo金属间化合物催化剂(PtCo/G-BC-S), 并通过旋转圆盘电极及单电池考察其电催化性能. XRD、Raman光谱、电导率测试和SEM结果表明, 碳热冲击处理后的碗状碳具有高的石墨化程度, 其电导率高达5.7 S cm-2 (20 MPa下), 为原始碗状碳的7倍, 同时依然维持原有碗状结构. 而对于普通管式炉煅烧后的碗状碳, 虽然石墨化程度得到提高,但其结构出现了严重的坍塌, 且比表面积下降严重. 电化学测试结果表明, PtCo/G-BC-S表现出较好的ORR催化性能, 在高电位(1.0-1.5 V)下G-BC-S具有高的耐腐蚀性能: PtCo/G-BC-S的半波电位(0.933 V)均高于PtCo/BC (0.928 V)和商业Pt/C(0.89 V). 此外, 高电位下的加速耐久性测试结果表明, PtCo/G-BC-S的半波电位只衰减了13 mV, 而PtCo/BC和商业Pt/C分别衰减了22 mV和47 mV. 以上研究结果表明, PtCo/G-BC-S催化剂的高活性和稳定性来自于两个方面: 铂钴金属间化合物催化剂的高活性和化学/结构稳定性, 以及碗状碳载体的高石墨化度和多孔结构.

提高碳载体的耐久性对燃料电池的稳定性至关重要, 其中通过提高石墨化来缓解碳腐蚀是重要方法之一. 综上, 本文为制备高耐久性碳载体提供了一种高效、经济的策略, 对推动燃料电池的发展具有借鉴意义.

关键词: 燃料电池, 碳腐蚀, 多孔碳, 石墨化, 碳热冲击

Abstract:

The electronic conductivity and durability of porous carbon supports can be improved by increasing the degree of graphitization in the material; however, the preparation of highly graphitic porous carbon using conventional furnaces remains a significant challenge. Herein, we demonstrate a universal and highly efficient carbothermal shock strategy that significantly improves the degree of graphitization of porous carbon supports, including bowl-like carbon, hollow carbon spheres, ZIF8-derived carbon, BP2000, and Ketjen EC 300J. Taking bowl-like carbon as an example, we illustrate the synthesis of a graphitized bowl-like carbon (G-BC-S) support and evaluate the performance of PtCo/G-BC-S in the oxygen reduction reaction (ORR) in rotating disk electrodes (RDE) and H2/air PEM single cells. PtCo/G-BC-S exhibits faster ORR kinetics than PtCo/BC and Pt/C, with little loss of activity (25%) and only 13 mV of E1/2 decay after 20000 cycles accelerated stress testing under 1.0-1.5 V vs. a reversible hydrogen electrode (RHE). The significantly enhanced performance of the PtCo/G-BC-S catalyst arises from the high activity and chemical/structural stability of the PtCo intermetallic nanoparticles and from the high degree of graphitization and well-defined porous structure of the bowl-like carbon support, which confers excellent electrical conductivity and oxygen transport properties. This study provides a reliable and universal strategy for the development of high-performance porous carbon supports for practical applications in fuel cells.

Key words: Fuel cell, Carbon corrosion, Porous carbon, Graphitization, Carbothermal shock