如何改变和优化离聚物在催化剂表面分布状态？相关内容：
不同炭黑载体中铂和离聚物分布状态对燃料电池性能和电位循环耐久性的影响
不同铂含量在炭黑内外表面分布状态对燃料电池性能和耐久性的影响：不同失效机理解读
还有其他的因素么？我们继续：
Improvement of Cell Performance inLow-Pt-Loading PEFC Cathode Catalyst Layers Prepared by the Electrospray Method
Kento Takahashi
Katsuyoshi Kakinuma
Makoto Uchida
Abstract
The reduction of Pt loading in cathodecatalysts is an important subject for developing polymer electrolyte fuelcells. In order to solve this problem without sacrificing performance, weprepared a uniform catalyst-coated membrane (CCM) by an electrospray (ES) method with a low Pt loading, 0.05 mg Pt cm−2, whichis one-tenth of the typical cathode Pt loading. The ES process has severaladvantages for the fabrication of thin catalyst layers (CLs), such as smaller droplets and accurate positioncontrol, compared with the pulse-swirl-spray (PSS，脉冲旋涡喷涂?) method. Highly uniform CLs wereevaluated by use of a standard evaluation cell (area 29.2 cm2). The ES methodmakes it possible to control precisely the coating area and reduce the lossesof the catalyst ink. CLs cross sections prepared by focused ion beam millingindicated that the total occupationfraction of the pores in the CLs prepared by the ES method was about twice aslarge as that for the PSS method. TheES method improved the ionomer coverage, led to increased electrochemicallyactive surface area, and constructed more porous CLs. The highly porous CLsprepared by the ES method contributed to the improvement of the cellperformance.
Figure 1. (a) Schematic drawing ofelectrospray (ES) process. (b) Steps of microparticle and nanoparticleproduction by ES.
Figure 2. (a) Mode changes of Taylor coneas a function of the nozzle-substrate distance and the applied voltage (A:drip-mode, B: cone-jet mode and C: multi-jet mode). (b) Relationships betweenthe applied voltage and the electric field for various nozzle-substratedistances.
Figure 3. Photographs of CLs on themembrane prepared by PSS method (a) and by ES method (b). Photographic imagesof droplets on the membrane prepared by the PSS method (c) and by ES method(d). The white dotted-line squares indicate the geometric area of the electrodes(29.2 cm2) in (a) and (b).
怎么说呢，这个对比例有点不厚道，都1cm多的平面偏差了就不能加个掩模么？
Thedroplet shapes also differed significantly and indicated that the PSS dropletswere wet, while the ES droplets were dry.
Figure 4. SEM cross-sectional images ofcathode CLs prepared by PSS method (a) and ES method (b), magnified images ofthe cathode CLs by PSS method (c) and ES method (d).
Figure 5. Relationship between cumulativepore volume and pore diameter of the carbon black.
Figure 6. (a) Cathode cyclic voltamogramsof ES-cathode-cell and PSS-cathode-cell at 80°C, 100% RH, and (b) Humiditydependence of the ECA of ES-cathode-cell and PSS-cathode-cell at 80°C.
Figure 7. Morphologies of the ionomercovered on carbon-supported Pt catalysts in the PSS electrode (a) and ESelectrode (b). The dashed line indicates the carbon surface, and the solid lineindicates the ionomer surface.
说是炭黑，这个电镜图像挺有特色，读了一下制备过程，空气测试用的是graphitized carbon black: TEC10EA30E
Suchan acceleration of the drying might have an effect on the ionomer coverage.
Figure 8. IR-free polarization curves forthe ES-cathode-cell and PSS-cathode-cell at 80°C, 80% RH, air/H2, ambientpressure.
Figure 9. Humidity dependence of massactivity at 0.85 V (IR-free), 80°C, air/H2, ambient pressure.
Figure 10. Humidity dependence of thecurrent density and the ohmic residence at 0.7 V (IR-free), 80°C, air/H2,ambient pressure.
Figure 11. Relationships between the O2gain and the current density under various humidity conditions, at 80°C,ambient pressure.
The O2 gains for both cells, which wereobtained under pure O2 and air feed, are shown in Fig. 11
Conclusions
We prepared and evaluated cathode CLs byuse of the ES method from Pt nanoparticle catalysts supported on CB. Byoptimizing the various preparationconditions, i.e., distance between the nozzle and membrane, the appliedvoltage, and the nozzle diameter, etc., we were able to obtain a stableejection of the submicrometer ink droplets. CLs with highly uniformcharacteristics were obtained. The ES method enabled us to precisely controlthe coated area and to reduce the loss of catalyst ink. The ES method also led to improved ionomer coverage, increased ECAvalues, and more highly porous CLs. The highly porous CL prepared by the ESmethod contributed to the improvement of the MA and the cell performance due tothe increased efficiency of gas mass transport at current densities below 0.5 Acm−2 at 80–100% RH. We propose that the new method using ES method for thepreparation of thin CLs with very Pt low loading might be attractive in orderto improve the performance and reduce costs for PEFCs.
