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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Polymer Electrolyte Membranes Incorporated with Nanometer-Size Particles of Pt and/or Metal-Oxides: Experimental Analysis of the Self-Humidification and Suppression of Gas-Crossover in Fuel Cells
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Polymer Electrolyte Membranes Incorporated with Nanometer-Size Particles of Pt and/or Metal-Oxides: Experimental Analysis of the Self-Humidification and Suppression of Gas-Crossover in Fuel Cells

机译：铂和/或金属氧化物纳米尺寸的聚合物电解质膜的结合：燃料电池中自加湿和抑制气体穿越的实验分析

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Self-humidification behaviors of polymer electrolyte membranes (PEMs) were clarified experimentally in polymer electrolyte fuel cells (PEFCs) operated with dry H↓(2) and O↓(2). New PEMs (Pt-PEM, TiO↓(2)-PEM, Pt-TiO↓(2)-PEM) were prepared by dispersing small amounts of Pt (1-2 nm in diameter) and/or metal-oxides such as TiO↓(2) (5 nm in diameter) in Nation 112 or a recasted Nation film (normal-PEM, ca. 50 μm in thickness). Distribution profiles of the specific resistances (ρ) in thickness direction were measured with monitoring Pt-probes inserted into the PEMs. In normal-PEM, the p increases with increase of current density at the anode side and vice versa at the cathode side, and this was pronounced at high current density. However, it was found that the ρ decreased monotonically at every portion in Pt-PEM with increase of current density, although the ρ of anode side is larger than that of cathode side. Further uniform p distribution was achieved in Pt-TiO↓(2)-PEM, i.e., #20 Ω cm at a practically operational current density. The mechanisms of such a distinctive self-humidification and a suppression of crossover of reactant gases in the new PEMs were clarified by monitoring consumed H↓(2) and O↓(2) and produced water in exhausting gases from PEFCs in comparison with normal-PEM. In Pt-TiO↓(2)-PEMs, crossover H↓(2) and O↓(2) were recombined on Pt particles and all of the water generated inside the PEMs was exhausted from the anode. The TiO↓(2) particles enhanced the back-diffusion of water produced by faradic reaction at the cathode by the hygroscopic property, resulting in very efficient humidification of the PEM of the anode side dried by the electroosmotic drag. It was also found that the new PEMs improve the cathode potential distinctively, which was ascribed to elimination of the short-circuit reaction of crossover gases in the cathode catalyst layer, resulting in a small non-faradic consumption of H↓(2) and no disturbance of reactant O↓(2) diffusion by the produced water vapor.
机译：实验证明了在干H↓（2）和O↓（2）下运行的聚合物电解质燃料电池（PEFC）中聚合物电解质膜（PEM）的自增湿行为。通过分散少量的Pt（直径1-2 nm）和/或金属氧化物（例如TiO）制备新的PEM（Pt-PEM，TiO↓（2）-PEM，Pt-TiO↓（2）-PEM） ↓（2）（直径5 nm）位于Nation 112或重铸的Nation膜（普通PEM，厚度约为50μm）中。通过监测插入PEM中的Pt探针，测量了厚度方向上的电阻率（ρ）的分布曲线。在普通的PEM中，p随着阳极侧电流密度的增加而增加，反之亦然，随着阴极侧电流密度的增加而增加，这在高电流密度下尤为明显。然而，发现尽管阳极侧的ρ大于阴极侧的ρ，Pt-PEM中的每个部分的ρ随着电流密度的增加而单调降低。在实际工作电流密度下，在Pt-TiO↓（2）-PEM中获得了更均匀的p分布，即＃20Ωcm。通过监测PEFC排放的H↓（2）和O↓（2）以及与普通PFC相比排放的废气中产生的水，阐明了这种独特的自加湿和抑制新的PEM中反应气体交叉的机理。 PEM。在Pt-TiO↓（2）-PEM中，交叉点H↓（2）和O↓（2）在Pt颗粒上重新结合，PEM内部产生的所有水都从阳极排出。 TiO↓（2）颗粒通过吸湿特性增强了法拉第反应在阴极上产生的水的反扩散，从而使通过电渗阻力干燥的阳极侧的PEM非常有效地加湿。还发现，新的PEMs显着提高了阴极电势，这归因于消除了阴极催化剂层中交叉气体的短路反应，从而导致了少量的非自由基消耗H↓（2），并且没有产生的水蒸气对反应物O↓（2）扩散的干扰。

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