文章构思和结论很有趣，但论证过程和证据有瑕疵和错误。不要迷信文献，读完全文，看看你是否赞同我对文章中错误的看法。

Effect of the CeO2 nanoparticles in microporous layers on the durability of proton exchange membrane fuel cells

Pengtao Wang

Chao Cai

Jinting Tan

Mu Pan

Abstract

In this work， the effect of the CeO2 in the microporous layer （MPL） on the durability of proton exchange membrane （PEM） fuel cells is investigated． The 400 h dry－wet accelerated stress test （AST） and the open－circuit voltage （OCV） holding testing were used to identify the function of CeO2 in the microporous layer （MPL） on the durability and performance of MEA． The results show that the performance decay of the sample with CeO2 is much smaller than the sample without CeO2 （e．g．， 24 mV vs． 140 mV＠ 1200 mA cm−2）． More importantly， the OCV decrease rate for sample without CeO2 is as high as 7．250μV／cycle， which is 9．6 times as the value of 0．752μV／cycle for sample with CeO2． And it is interesting that the addition of CeO2 in MPL does not increase the inner resistance in the cell． Therefore， the addition of CeO2 to the MPL not only can significantly improve the cell durability but also can effectively alleviate the negative impact of Ce ions on the proton conductivity in proton exchange membrane．

Fig． 1 Schematic of the diffusion of CeO2 doped in MPL．

MPL两侧均添加了CeO2。

至于为什么阳极多阴极少，从图1可以看到，文章的解释是

When the concentration of Ce ions in anode MPL is higher than that in
cathode， Ce ions will diffuse with acidic water from anode
through PEM to cathode catalytic layer to inhibit the radicals．

这个量是刻意控制的，但并没有说是实际添加的还是添加完测量到的。而且文章中没有说对这个参数的敏感性实验，只是为了对比。

Some commercial CeO2 （99．95％， ＜50 nm， Aladdin） were
taken into isopropyl alcohol and dispersed for 1－3 h with an
ultrasonic cleaner Then， the CeO2 dispersion was mixed into
carbon particles （Vulcan XC－72） and PTFE emulsion in
appropriate proportions． Subsequently， the above mixture
was stirred with an electric blender for about 2 h and then
dispersed with an ultrasonic cleaner for 1－3 h to prepare the MPL slurry． Followed by， amount of slurry was screenprinted
to a commercial gas diffusion base （SGL） and then
sintered in a tube furnace at 350 C for 0．5 h to prepare a gas
diffusion layer （GDL）． The total carbon loading in each sample
was fixed at 1．5 mg cm2 with 20 wt％ PTFE content．

催化层、碳纸主体和膜内没有添加铈，只在MPL中添加了铈。

但是文章漏说了一件事，

The MEA consisted of a sandwiched CCM with clamping GDLs
on both sides． 25 cm2－CCMs （catalyst coated membranes）
were provided by Wuhan university of technology New Energy
Company．

使用的电解质膜中有没有铈？

Fig． 2 Dry－wet AST． COCV法，没有联用HFR测试在一个干湿工况里的变化结果。

Fig． 3  Polarization curves at 0 h and 400 h of T2／T1．

400hr后T1的OCV出现问题。

Fig． 4   OCV degradation of a single cell for T2／T1 during
20，000 cycles．

工况共20000＊75s＝416hr

Fig． 5  Crossover current of T2／T1 during 20，000 cycles．

我以为我看错了，加了铈以后的T2应该是优等生才对。

又看了看原文，

The change of hydrogen crossover current density for T2 and
T1 during 400－h dry－wet AST is shown in Fig． 5． For T2， there
are no significant changes in hydrogen crossover during the
400 h AST， and the value is basically stable at 2．5 mA cm2．

这么明显的错误审稿人都没有看出来。我读的是article in press文档，也可能正式的文稿中改正了。

Fig． 6  Total F－ concentration in the drain water of cathode and anode （a） and cumulative F－ release amount （b） of T2／T1 during 400 h．

我看到图6的时候会看了一下实验部分感觉文章是有问题的。

F concentration of anode and cathode drain water was
measured every 24 h using a fluoride ion－selective electrode
（DIONEX AQUION）．

GB／T 7484－1987 水质  氟化物的测定  离子选择电极法 标准状态：现行

检测限是0．05mg／L＝50ug／L（50ppb），文章竟然准确测量2ug／L的数据。问题出在这篇文章的局部是模板套用的语句。DIONEX AQUION根本不是离子选择电极，而是Thermo Scientific离子色谱系统。

GB／T 31197－2014 无机化工产品 杂质阴离子的测定 离子色谱法未提及检测下限。

Thermo Scientific公开了一个文档，表格中说明了Limit of detection （LOD） and limit of quantitation （LOQ），氟离子的定量下限44ug／L（44ppb），和离子选择电极并无太大差异。

虽然不排除为了分析进行了产物浓缩，但是文章把离子选择电极和离子色谱系统放在一起应该是个明显错误。

和燃料电池膜电极加速测试中的元素成分迁移对比氟离子释放速度，T2样品1000ug／cm2／400hr＝2．5ug／cm2／hr，相对来说氟离子释放较快。

Fig． 7 e Cross－section of MEA before （a） and after （c） AST， CCM before （e） and after （g） AST， distribution of Ce element before
（b） and （d） after AST in MEA， Ce element before （f） and （h） after AST in CCM．

我读的是article in press文档，没有找到文中有egfh四张图，也可能正式的文稿中改正了。很遗憾没有看到ccm中铈的分布是什么样的。

常规膜中∼6．0 μg／cm2 ion－exchanged cerium。而在MPL中添加了60－106μg／cm2的铈，大了1个数量级。让人好奇更少量的添加，比如和膜中铈一样的水平是否有效果？

图中没有做归一化，看不到膜中的铈不知道是否和EDX的分辨有关。

Fig． 8 e （a） Impedance spectra before and after AST， and （b） cell internal resistance during the AST．

Conclusion

To improve the durability of the fuel cell through CeO2， and
meanwhile alleviate the negative impact of cerium ions on the
proton conductivity in the fuel cell， in this work， CeO2 nanoparticles
were mixed into the MPL． The 400－h dry－wet AST was
used to age the sample with CeO2 （T2） and sample without
CeO2 （T1）， the results have shown as below．

1） The performance decay of T2 is much smaller than T1 （e．g．，
24 mV vs． 140 mV＠ 1200 mA cm2）．
2） The OCV decrease rate is as high as 7．250mV／cycle for T1．
However， the value is only 0．752mV／cycle （9．6 times lower）
for T2．
3） The hydrogen crossover current increased from
2．6mAcm2 to 5．0mAcm2 （～2 times） for T1． However， the
value for T2 is basically unchanged．

这个渗氢电流不算很明显，但是对OCV却造成很大影响。这不好理解，极化曲线在高电密的衰减和膜有关，但并非本质关联。膜会降解，催化层的离聚物难道就不会降解么？
4） The cumulative F loss of T1 is about 2．8 times that of T2
after the AST．
5） EIS results have suggested that the internal resistance of T2
is lower than that of T1 （about 10％－20％） whether before or
after the AST． This indicates that the addition of CeO2 in
MPL will not cause obvious negative effects on the proton
conductivity in the cell．

In summary， the direct addition of CeO2 to the MPL can not
only significantly improve the durability of the PEM but also
can effectively alleviate the negative impact of cerium ions on
the proton conductivity in the fuel cell． All the results are
crucial for further development of long－life PEM fuel cell．