Novel thin/tunable gas diffusion electrodes with ultra-low catalyst loading for hydrogen evolution reactions in proton exchange membrane electrolyzer cells
Novel thin/tunable gas diffusion electrodes with ultra-low catalyst loading for hydrogen evolution reactions in proton exchange membrane electrolyzer cells
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DOI：
10.1016/j.nanoen.2018.03.015
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发表时间：
2018-05-01
期刊：
影响因子：
17.6
通讯作者：
Zhang, Feng-Yuan
中科院分区：
文献类型：
--
作者：
Kang, Zhenye;Yang, Gaoqiang;Zhang, Feng-Yuan
质子交换膜电解槽（PEMECs）因其在低温条件下的高效生产氢/氧而受到广泛关注。由于贵金属铂族金属（PGM）催化剂（Ir, Ru， Pt等）广泛用于水分解，其成本较高，因此迫切需要一种低催化剂负载和高催化剂利用率的PEMEC，以实现其广泛的商业化。本研究首次在现场观测了运行中的PEMEC中超快多尺度析氢反应（HER）现象。可视化结果表明，HER和氢泡成核主要发生在薄/可调液/气扩散层（tt - lgdl）孔边缘的催化剂层上。这表明位于LGDL孔中间区域的传统催化剂包覆膜（CCM）的催化剂材料未得到充分利用/无活性。基于这一发现，利用先进的微纳米制造技术，提出并开发了一种新型的薄可调气体扩散电极（GDE），其Pt催化剂厚度为15 nm，总厚度约为25 μ m。对新型薄gde进行了原位和非原位表征，并表现出优异的PEMEC性能。更重要的是，在80℃和1atm的工作条件下，它们在1.6 V下实现了比传统CCM高58倍的催化剂质量活性。该研究为PEMEC电极的发展提供了一个有希望的概念，并为未来电化学器件催化剂的设计和制造提供了方向。
Proton exchange membrane electrolyzer cells (PEMECs) have received great attention for hydrogen/oxygen production due to their high efficiencies even at low-temperature operation. Because of the high cost of noble platinum-group metal (PGM) catalysts (Ir, Ru, Pt, etc.) that are widely used in water splitting, a PEMEC with low catalyst loadings and high catalyst utilizations is strongly desired for its wide commercialization. In this study, the ultrafast and multiscale hydrogen evolution reaction (HER) phenomena in an operating PEMEC is in-situ observed for the first time. The visualization results reveal that the HER and hydrogen bubble nucleation mainly occur on catalyst layers at the rim of the pores of the thin/tunable liquid/gas diffusion layers (TT-LGDLs). This indicates that the catalyst material of the conventional catalyst-coated membrane (CCM) that is located in the middle area of the LGDL pore is underutilized/inactive. Based on this discovery, a novel thin and tunable gas diffusion electrode (GDE) with a Pt catalyst thickness of 15 nm and a total thickness of about 25 mu m has been proposed and developed by taking advantage of advanced micro/nano manufacturing. The novel thin GDEs are comprehensively characterized both ex-situ and in-situ, and exhibit excellent PEMEC performance. More importantly, they achieve catalyst mass activity of up to 58 times higher than conventional CCM at 1.6 V under the operating conditions of 80 degrees C and 1 atm. This study demonstrates a promising concept for PEMEC electrode development, and provides a direction of future catalyst designs and fabrications for electrochemical devices.