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摘要: 离子交换树脂（Ionomer）是质子交换膜燃料电池催化层的重要组成部分，它在催化层中的主要作用是作为质子传导相传导质子。本文采用旋转圆盘电极法（RDE），在模拟燃料电池真实的运行环境（模式一）和模拟燃料电池启停环境（模式二）两种模式下，研究了Ionomer对铂碳催化剂电压循环耐久性的影响。通过相同位置透射电镜分析法（IL-TEM），分析了铂碳催化剂经历模式二耐久性测试后的结构变化。研究发现Ionomer的存在可以提高铂碳催化剂的耐久性。在模式一的测试中：添加Ionomer后，其氧还原半波电位下降值∆E从23 mV下降至11 mV；没有发生碳的腐蚀，Pt颗粒的长大是催化剂性能下降的主要原因；Ionomer的存在延缓了Pt电化学比表面积（ECSA）的降低从而有利于保持Pt的活性。在模式二的测试中：添加Ionomer后，其氧还原半波电位下降值∆E从25 mV下降至5 mV，除了铂颗粒长大外还发生了载体碳的腐蚀；Ionomer的存在同样可以保持Pt的活性；IL-TEM分析可以看到明显的铂颗粒长大和碳腐蚀，碳载体的腐蚀造成铂的严重流失和团聚。含Nafion的催化剂中铂颗粒平均粒径从2.7 nm增加到了3.76 nm，不含Nafion的催化剂中的铂颗粒平均粒径从2.44 nm增加到了4.19 nm。
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关键词:
- 质子交换膜燃料电池 /
- 离子交换树脂 /
- Pt/C催化剂 /
- 耐久性 /
- 相同位置透射电镜(IL-TEM)
Abstract: Ionomer is an important part of the catalytic layer in proton exchange membrane fuel cell. Its main role is to conduct protons. We investigated the effect of ionomer on the durability of Pt/C catalyst using rotating disk electrode (RDE) under two modes: the real operating conditions (mode 1) and startup/shutdown conditions (mode 2). The structural changes of Pt/C catalyst after the durability test were analyzed by identical location transmission electron microscopy (IL-TEM). Results show that the addition of ionomer improved the durability of Pt/C catalysts. After the durability test of mode 1, the addition of ionomer reduced the change of half-wave potential (∆E1/2) of oxygen reduction reaction from 23 to 11 mV, which is attributed to the growth of Pt particles rather than carbon corrosion. Ionomer delayed the decrease of electrochemical specific surface area (ECSA) of Pt/C catalyst, which is beneficial to the maintenance of Pt activity. After the durability test of mode 2, in addition to the growth of platinum particles, carbon corrosion occurred in the catalyst layer, and the growth of platinum particles was mainly due to carbon corrosion. The addition of ionomer reduced the ∆E1/2 of oxygen reduction reaction from 25 to 5 mV. Furthermore, the growth of platinum particles and carbon corrosion can be clearly seen by IL-TEM, and the corrosion of the carbon support resulted in the loss and agglomeration of platinum. The average particle size of platinum in Nafion-containing catalyst increased from 2.7 to 3.76 nm, while that of Nafion-free catalyst increased from 2.44 nm to 4.19 nm. -
图 1 模拟燃料电池真实的运行环境的加速模式图（a）和模拟燃料电池启停环境的加速模式图（b）
Figure 1. Acceleration mode diagram that simulates the real operating environment of the fuel cell (a) and acceleration mode diagram that simulates the start-stop environment of the fuel cell (b)
图 2 金色TEM网格和PTFE（聚四氟乙烯）盖固定在GC尖端上
Figure 2. Golden TEM grid and PTFE cap are fixed on the GC tip
图 3 样品一（a）和样品二（b）按模式一经历0、3×103、6×103和104次循环后的CV曲线和ECSA的变化情况（c）
Figure 3. CV curves of sample 1 (a) and sample 2 (b) after 0, 3×103, 6×103和104 cycles in mode 1, and changes in ECSA (c)
图 4 样品一（a）和样品二（b）在0、3×103、6×103和104次循环后的LSV曲线
Figure 4. LSV curves of sample 1 (a) and sample 2 (b) after 0, 3×103, 6×103 and 104 cycles
图 5 样品一（a）和样品二（b）按模式二经历0、3×103、9×103和2.7×104次循环后的CV曲线和ECSA的变化情况（c）
Figure 5. CV curves of sample 1 (a) and sample 2 (b) after 0, 3×103, 9×103, and 2.7×104 cycles in mode 2, and changes in ECSA (c)
图 6 样品一(a)和样品二（b）经历0、3×103、9×103和2.7×104次循环后的LSV曲线
Figure 6. LSV curves of sample 1(a) and sample 2 (b) after 0, 3×103, 9×103, and 2.7×104 cycles
图 7 样品一在耐久性测试前（a, c）和2.7×104次耐久性循环测试后（b, d）相同位置的TEM电镜图（a, b）和催化剂粒径分布图（c, d）
Figure 7. TEM electron microscope image of the same position of the catalyst (a, b) and catalyst particle size distribution diagram (c, d) in sample 1 before the durability test (a, c), and after the 2.7×104 durability cycle test (b, d)
图 8 样品二在耐久性测试前（a, c）和2.7×104次耐久性循环测试后（b, d）相同位置的TEM电镜图（a, b）和催化剂粒径分布图（c, d）
Figure 8. TEM electron microscope image of the same position of the catalyst (a, b) and catalyst particle size distribution diagram (c, d) in sample 2 before the durability test (a, c), and after the 2.7×104 durability cycle test (b, d)
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参考文献
[1] Cherevko S, Kulyk N, Mayrhofer K J J. Durability of platinum-based fuel cell electrocatalysts: Dissolution of bulk and nanoscale platinum. Nano Energy, 2016, 29: 275 doi: 10.1016/j.nanoen.2016.03.005 [2] Sun S, Liu Z D, Diao P. Preparation and catalytic studies of pyrrole-doped carbon black oxide cathode materials for oxygen reduction reactions. Chin J Eng, 2019, 41(2): 216孙珊, 刘桎东, 刁鹏. 吡咯/炭黑氧化物复合氧阴极材料的制备及催化性能. 工程科学学报, 2019, 41(2):216 [3] Souza N E, Bott-Neto J L, Rocha T A, et al. Support modification in Pt/C electrocatalysts for durability increase: A degradation study assisted by identical location transmission electron microscopy. Electrochimica Acta, 2018, 265: 523 doi: 10.1016/j.electacta.2018.01.180 [4] Bandarenka A S, Ventosa E, Maljusch A, et al. Techniques and methodologies in modern electrocatalysis: Evaluation of activity, selectivity and stability of catalytic materials. Analyst, 2014, 139(6): 1274 doi: 10.1039/c3an01647a [5] Huang K, Zhu M T, Zhang F P, et al. Preparation of CoP/Co@NPC@rGO nanocomposites with an efficient bifunctiona electrocatalyst for hydrogen evolution and oxygen evolution reaction. Chin J Eng, 2020, 42(1): 91黄康, 朱梅婷, 张飞鹏, 等. 一种高效双功能电催化剂CoP/Co@NPC@rGO的制备. 工程科学学报, 2020, 42(1):91 [6] Arenz M, Zana A. Fuel cell catalyst degradation: Identical location electron microscopy and related methods. Nano Energy, 2016, 29: 299 doi: 10.1016/j.nanoen.2016.04.027 [7] Meier J C, Galeano C, Katsounaros I, et al. Degradation mechanisms of Pt/C fuel cell catalysts under simulated start–stop conditions. ACS Catal, 2012, 2(5): 832 doi: 10.1021/cs300024h [8] Hartl K, Hanzlik M, Arenz M. IL-TEM investigations on the degradation mechanism of Pt/C electrocatalysts with different carbon supports. Energy Environ Sci, 2011, 4(1): 234 doi: 10.1039/C0EE00248H [9] Zana A, Speder J, Roefzaad M, et al. Probing degradation by IL-TEM: The influence of stress test conditions on the degradation mechanism. J Electrochem Soc, 2013, 160(6): F608 doi: 10.1149/2.078306jes [10] Speder J, Zana A, Spanos I, et al. Comparative degradation study of carbon supported proton exchange membrane fuel cell electrocatalysts - The influence of the platinum to carbon ratio on the degradation rate. J Power Sources, 2014, 261: 14 doi: 10.1016/j.jpowsour.2014.03.039 [11] Hengge K, Gänsler T, Pizzutilo E, et al. Accelerated fuel cell tests of anodic Pt/Ru catalyst via identical location TEM: New aspects of degradation behavior. Int J Hydrog Energy, 2017, 42(40): 25359 doi: 10.1016/j.ijhydene.2017.08.108 [12] Arán-Ais R M, Yu Y C, Hovden R, et al. Identical location transmission electron microscopy imaging of site-selective Pt nanocatalysts: Electrochemical activation and surface disordering. J Am Chem Soc, 2015, 137(47): 14992 doi: 10.1021/jacs.5b09553 [13] Sakthivel M, Drillet J F. An extensive study about influence of the carbon support morphology on Pt activity and stability for oxygen reduction reaction. Appl Catal B:Environ, 2018, 231: 62 doi: 10.1016/j.apcatb.2018.02.050 [14] Schonvogel D, Hülstede J, Wagner P, et al. Stability of Pt nanoparticles on alternative carbon supports for oxygen reduction reaction. J Electrochem Soc, 2017, 164(9): F995 doi: 10.1149/2.1611709jes [15] Gasteiger H A, Kocha S S, Sompalli B, et al. Activity benchmarks and requirements for Pt, Pt-alloy, and non-Pt oxygen reduction catalysts for PEMFCs. Appl Catal B:Environ, 2005, 56(1-2): 9 doi: 10.1016/j.apcatb.2004.06.021 [16] Inaba M, Jensen A W, Sievers G W, et al. Benchmarking high surface area electrocatalysts in a gas diffusion electrode: Measurement of oxygen reduction activities under realistic conditions. Energy Environ Sci, 2018, 11(4): 988 doi: 10.1039/C8EE00019K [17] Nonoyama N, Okazaki S, Weber A Z, et al. Analysis of oxygen-transport diffusion resistance in proton-exchange-membrane fuel cells. J Electrochem Soc, 2011, 158(4): B416 doi: 10.1149/1.3546038 [18] Kongkanand A, Mathias M F. The priority and challenge of high-power performance of low-platinum proton-exchange membrane fuel cells. J Phys Chem Lett, 2016, 7(7): 1127 doi: 10.1021/acs.jpclett.6b00216 [19] Kocha S S, Zack J W, Alia S M, et al. Influence of ink composition on the electrochemical properties of Pt/C electrocatalysts. ECS Trans, 2013, 50(2): 1475 doi: 10.1149/05002.1475ecst [20] Ohma A, Fushinobu K, Okazaki K. Influence of Nafion® film on oxygen reduction reaction and hydrogen peroxide formation on Pt electrode for proton exchange membrane fuel cell. Electrochimica Acta, 2010, 55(28): 8829 doi: 10.1016/j.electacta.2010.08.005 [21] Mayrhofer K J J, Ashton S J, Meier J C, et al. Non-destructive transmission electron microscopy study of catalyst degradation under electrochemical treatment. J Power Sources, 2008, 185(2): 734 doi: 10.1016/j.jpowsour.2008.08.003 [22] Schlögl K, Hanzlik M, Arenz M. Comparative IL-TEM study concerning the degradation of carbon supported Pt-based electrocatalysts. J Electrochem Soc, 2012, 159(6): B677 doi: 10.1149/2.035206jes [23] Yu Y C, Xin H L, Hovden R, et al. Three-dimensional tracking and visualization of hundreds of Pt−Co fuel cell nanocatalysts during electrochemical aging. Nano Lett, 2012, 12(9): 4417 doi: 10.1021/nl203920s [24] Nikkuni F R, Dubau L, Ticianelli E A, et al. Accelerated degradation of Pt3Co/C and Pt/C electrocatalysts studied by identical-location transmission electron microscopy in polymer electrolyte environment. Appl Catal B:Environ, 2015, 176-177: 486 doi: 10.1016/j.apcatb.2015.04.035 [25] Vion-Dury B, Chatenet M, Guétaz L, et al. Determination of aging markers and their use as a tool to characterize Pt/C nanoparticles degradation mechanism in model PEMFC cathode environment. ECS Trans, 2019, 41(1): 697 doi: 10.1149/1.3635604 -
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