PEMFC阴极催化层结构分析

doi:10.13208/j.electrochem.201208

摘要/Abstract

摘要：

采用CCS法（catalyst coated substrate）构建铂纳米颗粒（Pt-NPs）和铂纳米线（Pt-NWs）双层催化层结构,分析其对单电池电化学性能的影响。对于富铂/贫铂双层铂纳米颗粒结构,靠近质子交换膜侧的富铂层中致密的铂颗粒结构能促进ORR速率,而靠近气体扩散层一侧的具有更高的孔隙率和平均孔尺寸的贫铂层,有利于反应气体的传输和扩散,当贫富铂层铂载量比为1:2时,单电池测试表现出最优性能,在0.6 V时的电流密度达到了1.05 A·cm^-2,峰值功率密度为0.69 W·cm^-2,较常规单层催化层结构提升了21%。在以Pt-NPs作为基底层时生长Pt-NWs时,得到了梯度分布的双层结构。铂颗粒的存在促进了铂前驱体的还原,并为新形成的铂原子提供了沉积位置。在Pt-NPs基底上生长的Pt-NWs具有更均匀的分布以及更致密的绒毛结构,并且自然形成了一种梯度分布。优化后的Pt-NWs催化层在0.6 V时的电流密度提高了21%。含有双层催化层结构的膜电极具有更高的催化剂利用率,对阴极催化层结构的优化和制备提供了新思路。

关键词: 质子交换膜燃料电池, 双层催化层, 膜电极, 阴极, 铂纳米线

Abstract:

The sluggish oxygen reduction reaction (ORR) on the cathode of the proton exchange membrane fuel cell (PEMFC) has always been one of the key factors limiting its commercialization. The optimization of the cathode catalytic layer structure plays an important role in improving fuel cell performance and reducing production costs. In this paper, two different catalysts (platinum nanoparticles (Pt-NPs) and platinum nanowires (Pt-NWs)) were prepared by using catalyst coated substrate (CCS) method. By constructing a double-layer catalytic layer structure, we analyzed the effect of different catalytic layer structures by performing a single cell test. The results showed that the dense platinum particle structure in the Pt-rich layer near the proton exchange membrane could promote the ORR rate, while the Pt-poor layer near the gas diffusion layer had higher porosity and average pore size, which is beneficial to the reaction gas transmission and diffusion. When the platinum loading ratio of the rich to poor platinum layer was 1:2, the best single cell performance was achieved. The current density at 0.6 V reached 1.05A·cm^-2, and the maximum power density was 0.69 W·cm^-2. Compared with the single-layer structure, the peak power density was increased by 21%. When growing Pt-NWs on the Pt-NPs base layer, the presence of Pt particles promoted the reduction of platinum precursors and provided deposition sites for newly formed Pt atoms, and the grown Pt-NWs had a more uniform distribution as well as a denser pile structure. The current density of the optimized Pt-NWs catalytic layer structure at 0.6 V increased by 21%. The MEA fabricated by double-catalytic layer method had a higher catalyst utilization rate and a guiding significance for the optimization of the cathode catalytic layer structure. The high activity shown by the platinum nanowires provides a new idea for the preparation of efficient catalysts.

Key words: proton exchange membrane fuel cell, double-layer catalytic layer, membrane electrode assembly, cathode, platinum nanowires

王睿卿, 隋升. PEMFC阴极催化层结构分析[J]. 电化学（中英文）, 2021, 27(6): 595-604.

Rui-Qing Wang, Sheng Sui. Structure Analysis of PEMFC Cathode Catalyst Layer[J]. Journal of Electrochemistry, 2021, 27(6): 595-604.

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MEA No.	Pt poor layer			Pt rich layer
MEA No.	Pt loading/(mg·cm^-2)	Pt content	Method	Pt loading/(mg·cm^-2)	Pt content	Method
MEA#1	0.2	40%	Pt-NPs	-	-	-
MEA#2	0.2	67%	Pt-NWs	-	-	-
MEA#3	0.05	40%	Pt-NPs	0.15	60%	Pt-NPs
MEA#4	0.1	40%	Pt-NPs	0.1	60%	Pt-NPs
MEA#5	0.15	40%	Pt-NPs	0.05	60%	Pt-NPs
MEA#6	0.07	40%	Pt-NPs	0.13	60%	Pt-NPs
MEA#7	0.04	40%	Pt-NPs	0.16	60%	Pt-NPs
MEA#8	0.07	58%	Pt-NWs	0.13	72%	Pt-NWs
MEA#9	0.05	40%	Pt-NPs	0.15	75%	Pt-NWs

Method	Design loading/μg	Real loading/μg	Pt mass loss/%
Pt-NPs	400	281.4	30
Pt-NWs	200	182.5	8.75