文章標(biāo)題：

Intercalation and delamination of layered carbides and carbonitrides

DOI:?10.1038/ncomms2664

1.?“Ti3C2(OH)xOyFz”

“It is important to note at the outset that the 2D MXene surfaces are not M-terminated, but covered with oxygen-containing groups, such as OH, and fluorine (F) introduced after etching with aqueous hydrofluoric acid (HF). The chemistry of exfoliated MXene produced by HF etching of Ti3AlC2?is much closer to Ti3C2(OH)xOyFz?than to the idealized structure of a pure carbide layer Ti3C2. Henceforth, and for brevity’s sake, f-Ti3C2?will be used instead of the more cumbersome Ti3C2(OH)xOyFz.?”

“首先要注意的是，二維MXene表面不是M端，而是覆蓋著含氧基團(tuán)，如OH，以及用氫氟酸水溶液（HF）蝕刻后引入的氟（F）。通過HF蝕刻Ti3AlC2而產(chǎn)生的剝落MXene的化學(xué)性質(zhì)要比純碳化物層Ti3C2(OH)xOyFz的理想化結(jié)構(gòu)更接近于Ti3C2。因此，為了簡潔起見，將使用f-Ti3C2而不是更麻煩的Ti3C2（OH）xOyFz。”

2. 插層劑的發(fā)現(xiàn)?

“The original aim of this work was to reduce the f-Ti3C2?surfaces to create Ti-terminated surfaces that theory predicts would be magnetic.?A perusal of the graphene literature made it clear that hydrazine monohydrate N2H4·H2O (HM) dissolved in?N,N-dimethylformamide (DMF) is the reactant of choice. Since in our case, HM was found to primarily act as an intercalant rather than a reducing agent, the research objectives were redirected towards intercalation and delamination of MXenes. Furthermore, as the layered structures of the MXenes retain some similarities to clays, we reviewed the intercalation chemistries of the latter. Numerous compounds, such as formamide and its derivatives, dimethyl sulphoxide (DMSO), urea and long-chain alkylamines, among others have been shown to intercalate clays. For clays, HM is probably the most common intercalant; its intercalation results in the increase of kaolinite’s?c-lattice parameter (c-LP) from 7.2 to 10.3–10.4???”

“這項(xiàng)工作的最初目的是減少f-Ti3C2的表面，以創(chuàng)造理論預(yù)測的Ti端面，使之具有磁性。仔細(xì)閱讀石墨烯文獻(xiàn)后，發(fā)現(xiàn)溶解在N,N-二甲基甲酰胺（DMF）中的一水肼N2H4-H2O（HM）是首選的反應(yīng)劑。由于在我們的案例中，HM被發(fā)現(xiàn)主要作為插層劑而不是還原劑，研究目標(biāo)被重新定向到MXenes的插層和分層。此外，由于MXenes的層狀結(jié)構(gòu)與粘土有一些相似之處，我們審查了后者的插層化學(xué)。許多化合物，如甲酰胺及其衍生物、二甲基亞砜（DMSO）、尿素和長鏈烷基胺等已被證明可以使粘土插層。對于粘土，HM可能是最常見的插層劑；它的插層導(dǎo)致高嶺土的c-lattice參數(shù)（c-LP）從7.2增加到10.3-10.4 ??”

3. 插層前后電阻率變化?

“In addition, the electrical resistivities of non-intercalated MXenes and MXenes treated with HM were measured. The resistivity values of all intercalated samples were higher than those of non-intercalated MXenes presumably owing to the increase of their?c-LPs after intercalation?. The differences in the magnitudes of the resistivity increases for different intercalated MXenes, at relatively the same expansion, can be partially explained by the different number of MXene atomic layers. In case of M3X2?(five atomic layers), the resistivity increases by an order of magnitude, whereas an increase by two orders is observed for the M2C (three atomic layers) compounds.”

“此外，還測量了非插層MXenes和用HM處理的MXenes的電阻率。所有插層樣品的電阻率值都高于非插層MXenes，這可能是由于插層后其c-LPs的增加（補(bǔ)充表S1）。在相對相同的膨脹下，不同的插層MXenes的電阻率增加的幅度不同，可以部分地解釋為MXene原子層的數(shù)量不同。在M3X2（五個原子層）的情況下，電阻率增加了一個數(shù)量級，而M2C（三個原子層）的化合物則增加了兩個數(shù)量級?！?/p>

4. MXene分層?

“We also tried to intercalate thiophene, ethanol, acetone, tetrahydrofuran, formaldehyde, chloroform, toluene, hexane, DMF, DMSO and urea into f-Ti3C2?at room temperature. Of these, only DMSO and urea resulted in an increase in the?c-LPs from 19.5±0.1?? to 35.04±0.02?? and 25.00±0.02??, respectively .?”

“我們還嘗試在室溫下將噻吩、乙醇、丙酮、四氫呋喃、甲醛、氯仿、甲苯、正己烷、DMF、DMSO和尿素插進(jìn)f-Ti3C2。其中，只有DMSO和尿素導(dǎo)致c-LPs從19.5±0.1 ?分別增加到35.04±0.02 ?和25.00±0.02 ?（補(bǔ)充圖S5）。由此可見，DMF只在有HM的情況下插進(jìn)f-Ti3C2。不管是不是巧合，在上述的有機(jī)化合物列表中，只有DMSO和尿素插層成功。”

5. 分層MXene的儲能應(yīng)用?

“To date, our Li-ion work was carried out on stacked multilayer particles. The breakthrough presented herein, however, allowed us to measure Li-ion uptake on d-Ti3C2?‘paper’.?As shown in?Fig. 4d, the capacity of the latter is a factor of 4 higher than that of as-synthesized f-MXene.”

“到目前為止，我們的鋰離子工作是在堆疊的多層顆粒上進(jìn)行的。然而，本文提出的突破使我們能夠測量d-Ti3C2 "紙 "上的鋰離子吸收量。如圖4d所示，后者的容量比合成的f-MXene的容量高4倍?！?/p>

6. 插層方法?

“To intercalate f-MXene with HM, the f-MXene powders were suspended either in HM or a 1:3 mixture of HM and DMF, and magnetically stirred for 24?h , either at room temperature (RT) or at 80?°C. In all cases, the weight ratio of HM:MXene was 10:1. When the treatment involved only HM, the suspensions were filtered and washed with ethanol. In case of intercalation with HM/DMF mixture, DMF was used for washing instead of ethanol. The powders were then dried in a desiccator under vacuum (<10?Torr) at RT for 24?h or in the vacuum oven (~10?2?Torr) at 120?°C for 24?h.

Intercalation of other organic compounds was attempted. Those included DMSO, urea, DMF, acetone, ethyl alcohol, tetrahydrofuran, chloroform, toluene, thiophene and formaldehyde. In all cases, the intercalation procedure was the same: (i) 0.3?g of f-Ti3C2 were mixed with 5?ml of each of the organic compounds listed above (excluding urea), then magnetically stirred for 24?h at RT; (ii) in the case of urea, 5?ml of 50?wt.% aqueous solution of urea was added to 0.3?g of f-Ti3C2 and stirred for 24?h at 60?°C. Later, the resulting colloidal solutions were filtered and dried in a desiccator under vacuum (<10?Torr) at RT. A detailed experimental section (materials used, techniques of material preparation and de-intercalation of MXenes) can be found in the Supplementary Methods.?”

“為了使f-MXene與HM插層，將f-MXene粉末懸浮在HM或HM與DMF的1:3混合物中，并在室溫（RT）或80℃下磁力攪拌24小時。在所有情況下，HM：MXene的重量比為10：1。當(dāng)處理只涉及HM時，懸浮液被過濾并用乙醇洗滌。在用HM/DMF混合物進(jìn)行插層的情況下，用DMF代替乙醇進(jìn)行洗滌。然后將粉末在真空（<10 Torr）下的干燥器中干燥24小時，或在120℃的真空爐（~10-2 Torr）中干燥24小時。

還嘗試了其他有機(jī)化合物的夾層。這些包括DMSO、尿素、DMF、丙酮、乙醇、四氫呋喃、氯仿、甲苯、噻吩和甲醛。在所有情況下，插層程序是相同的：（i）將0.3克f-Ti3C2與上述每種有機(jī)化合物（不包括尿素）的5毫升混合，然后在RT磁力攪拌24小時；（ii）在尿素的情況下，將5毫升50重量％的尿素水溶液加入0.3克f-Ti3C2中，在60℃攪拌24小時。之后，將得到的膠體溶液過濾，并在RT的真空（<10托）下在干燥器中進(jìn)行干燥。詳細(xì)的實(shí)驗(yàn)部分（所用材料、材料制備技術(shù)和MXenes的去插層）可以在補(bǔ)充方法Microsoft Word - Intercalation and Delamination Supporting info - clean copy[3].docx (springer.com)中找到?！?/p>