SCI论文写作之Experimental Section（二）

前期内容链接：

前言：

之前跟大家介绍过Experimental section里面的Characterizations部分，今天接着来讲讲Experimental里面最核心的一个部分——实验过程，包括Materials synthesis和Activity measurement等。为什么说这一部分是Experimental里面最核心的部分呢？因为如果别人对你的论文感兴趣，需要重复你的论文，所能参考的最主要的就是这个部分。而你的实验过程写得是不是清晰，是不是详细，很大程度上能够体现出你的科研素养。这里鼓励大家将实验细节写得尽可能清楚，因为真正的科研工作者从来不是因为在论文中隐瞒关键技术而牛逼的！

评价实验过程是不是写得清楚的唯一标准是：别人能够按着你所写的步骤完全重复你的实验！

实例分析：

参考文献：J. Am.Chem. Soc. 2014, 136, 6744−6753,来自University of Oregon的Shannon Boettcher group.

Film deposition. Prior to film deposition, substrates were cycled three times in 1 M KOH from 0.0−0.8 V vsHg/HgO. Substrates were rinsed with 18.2 MΩ·cm H₂O before being transferred to the deposition solution. Films of Ni(OH)₂ were cathodically deposited from unstirred solutions of 0.1 M Ni(NO₃)₂·6H₂O (Sigma Aldrich, 99.999% trace metals basis) in 18.2 MΩ·cm H₂O. As deposited Ni(OH)₂ films showed no XPS signal for Fe (see discussion below). For films containing codeposited Fe, the total metal content in the deposition solutionwas held at 0.1 M, and FeCl₂·4H₂O (Sigma Aldrich,>98%) was added. The solutions were purged with N₂ gas for at least 20 min before adding FeCl₂·4H₂O to prevent precipitation of insoluble FeOOH. Typical depositions at −0.1 mA cm⁻² for 120 s gave effective film thicknesses of ∼40 nm (see Figure S1 in the Supporting Information for a typical deposition profile and QCM frequency measurement). After deposition, films were rinsed by dipping in H₂O before being transferred to the electrochemical cell. The Fe/Ni ratio in the films was higher than that in the deposition solutions; however, any given Fe content insolution consistently produced films with the same Fe content (< ± 4%) asdetermined by XPS. All film Fe contents reported here are those measured by XPS.

逐句分析：

第一句：

    Prior to film deposition, substrates were cycled three times in 1 M KOH from 0.0−0.8 V vs Hg/HgO.这一句话交代了制备电极前载体是如何处理的，请注意红色标记的文字，特别是数字。这些文字指明了处理次数，溶液（包括浓度），循环伏安处理的电压范围。

注意：数字是Experimental section里面最重要的内容，要特别注意。

    同样的内容，如果很粗糙的写的话，有人可能会写成这样：

    All substrates were cycled in KOH solutionprior to film deposition.

    这句话有问题么？实际上也没什么问题，不过将数字剔除之后，别人再来重复你的实验，所采用的条件可能就会与你的真实实验条件有比较大的差异。

第二句：

    Substrates were rinsed with 18.2 MΩ·cm H₂Obefore being transferred to the deposition solution.这句话交代了substrate转移到电沉积溶液之前的处理过程。如果粗糙一些，这句话可不可以删除呢？其实好像问题也不大，不过从严谨的科研态度以及对读者负责任的角度来说，作者有义务提醒读者注意这些操作细节方面的问题。

第三句：

    Films of Ni(OH)₂ were cathodically deposited from unstirred solutions of 0.1 M Ni(NO₃)₂·6H₂O (Sigma Aldrich, 99.999% trace metals basis) in 18.2 MΩ·cm H₂O.这一句简单地交代了一下电化学沉积的方法，还是提醒大家注意下红色文字。数值，细节值得关注！

    备注：在Experimental section里面，对试剂出处的交代有两种方法，一种是像这里列出来的一样，在第一次出现这个试剂的时候注明厂家，纯度等关键信息；还有一种方式，以加一个Reagents部分，将本文中所有用到的试剂统一交代，注明厂家，纯度以及有无特殊处理等等。

第四句：

    As deposited Ni(OH)₂ films showed no XPS signal for Fe (see discussion below). 这句话对制备的Ni(OH)₂样品进行了简单的说明。这句话可以不写，因为在正文中还会讨论，不过加上会让读者读起来更加容易一些。

第五句：

For films containing codeposited Fe, the total metal content in the deposition solution was held at 0.1M, and FeCl₂·4H₂O(Sigma Aldrich, >98%) was added. 这句话特别交代了NiFeOOH样品的制备条件，还是提醒大家注意红色字体部分。

第六句：

The solutions were purged with N₂ gas for at least 20 min before adding FeCl₂·4H₂O to prevent precipitation of insoluble FeOOH.这一句话很重要，因为这是实验操作中很重要的一个细节，在溶解FeCl₂之前一定要充氮气，而且最好要充20 min来赶跑溶解的O₂，否则FeCl₂很有可能被氧化成FeOOH，进而影响电化学沉积的效果。再次提醒：基于对读者负责任的角度，实验中重要的细节一定要交代，不要藏着掖着。请记住：你对科研的贡献不是你会而别人不会，而是有一天你能教会大家之前所不会的。

第七句：

Typical depositions at −0.1 mA cm⁻² for 120 s gave effective film thicknesses of ∼40 nm (see Figure S1 in the Supporting Information for a typical deposition profile and QCM frequency measurement).这句话对具体的电化学沉积条件进行了说明。数字！！！

第八句：

After deposition, films were rinsed by dippingin H₂O before being transferred to the electrochemical cell.第八句跟第四句一样，还是提醒读者注意一些细节。如果在转移之前不润洗的话，电极上残余的FeCl2溶液就会跟1 M KOH在电解池中反应，影响测试结果。

第九句：

The Fe/Ni ratio in the films was higher than that in the deposition solutions; however, any given Fe content insolution consistently produced films with the same Fe content (< ± 4%) as determined by XPS. All film Fe contents reported here are those measured by XPS.这句话告诉读者结果中可能会存在的一些细节问题。写到这，我只能说Shannon太贴心了，真是手把手教读者做实验，任何在实验中可能会出现的细节问题都有交代。鼓励大家向Boettcher group学习，尽量让实验过程具体一点（具体跟啰嗦是两回事哈，语言还是要紧凑，废话不要写）。

后记：

做一个严谨和负责任的科研工作者，从Experimental section开始！共勉，我的朋友们！

鸟语虫声总是传心之诀，花英草色无非见道之文！

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