忌水性布羅氏酸型離子液體內探討銅的電化學研究及電沉積銅與銅合金應用於硝酸根還原與葡萄糖氧化

Electrochemical Study and Electrodeposition of Copper and Copper Alloy from Hydrophobic Br??nsted Acidic Ionic Liquid and Applications to Nitrate Reduction and Glucose Oxidation

邵毅安(Yi-An Shao)

指導教授 ： 陳泊余

高雄醫學大學/生命科學院/醫藥暨應用化學系碩士班/碩士(2018年)

摘要

本研究在質子化雙三氟甲基磺醯亞胺甜菜鹼(protonated betaine bis(trifluoromethylsulfonyl)imide)及水的混合電解液(Hbet-TFSI/H2O)中探討Cu(II)以及Cu(II)/Pb(II)的電化學行為。Cu(II)與Pb(II)的來源分別是氧化銅(CuO)、氧化亞銅(Cu2O)與氧化鉛(PbO)。當CuO與Cu2O分別溶解於Hbet-TFSI/H2O時，根據紫外-可見光譜所示，兩種銅來源在電解液中確實會產生相同的Cu(II)物種，這表示Cu(I)會被空氣氧化成Cu(II)。由NMR光譜則可以發現Cu2+會跟[bet]兩性離子和水分子共同配位而不是與[TFSI]陰離子配位。使用玻璃碳電極(GCE)和不鏽鋼電極(SSE)在不同溫度下進行循環伏安實驗。在GCE所掃描的伏安圖顯示出Cu(II)物種會經過Cu(I)狀態再還原成Cu(0)，且Cu(I)會發生不對稱反應"2Cu(I)→Cu(0)+Cu(II)" 。氧化方向則可觀察到"Cu(0)→Cu(II)+" 〖"2e" 〗^"-" 的氧化剝除峰。接著將CuO和PbO共同溶解於Hbet-TFSI/H2O中並探討Cu(II)/Pb(II)的電化學行為。從伏安圖中可以觀察到銅和鉛各別的氧化還原訊號，並在銅和鉛的還原訊號之間發現到鉛在銅上的欠電位沉積(UPD)現象。
使用SSE當作基材在不同溫度以及不同沉積電位下電沉積出銅與銅鉛合金，並藉由掃描式電子顯微鏡(SEM)和元素半定量分析(EDX)觀察其鍍層的表面型態與組成比例。可藉由含有Cu(II)的電解液在SSE上電沉積出高純度的銅。也可從含有Cu(II)與Pb(II)的混合液中電沉積出銅鉛合金。銅沉積物的表面型態為樹枝狀，而鉛銅合金則為花簇狀。銅沉積物的粉末XRD繞射圖顯示出比較傾向於(111)的晶格面。鉛銅合金則呈現非晶體結構，僅於40°C下且於較負沉積電位所得之鉛銅合金才顯現各自的銅、鉛晶體訊號。
最後將銅沉積物與銅鉛合金分別在pH 5 PBS緩衝溶液和0.1 M NaOH(aq）中應用於硝酸根還原以及葡萄糖氧化實驗。在硝酸根還原以及葡萄糖氧化實驗中，SSE/Cu86Pb14(-0.12V,40°C)顯示出大的反應電流密度、好的催化活性以及在30分鐘內有良好的穩定性。

關鍵字

離子液體 ； 氧化銅 ； 電沉積 ； 硝酸根還原 ； 葡萄糖氧化

並列摘要

In this study, the electrochemical behavior of Cu(II) and Cu(II)/Pb(II) were investigated in protonated betaine bis(trifluoromethylsulfonyl)imide/water electrolyte (Hbet-TFSI/H2O).
The sources of Cu(II) and Pb(II) were cupric oxide (CuO), cuprous oxide (Cu2O) and lead oxide (PbO), respectively. When CuO and Cu2O were dissolved in Hbet-TFSI/H2O, the same Cu(II) species were produced, which were confirmed by the UV-Vis spectroscopic studies indicating that Cu(I) was oxidized by air to be Cu(II). The NMR spectra indicated that the [bet] zwitterions and H2O molecules rather than the [TFSI] anions simultaneously coordinated with Cu2+. Cyclic voltammetry was performed at different temperatures using glass-carbon (GCE) and stainless steel (SSE) working electrodes in the solutions with two different copper sources. However, the same electrochemical behavior of copper was observed. The cyclic voltammograms recorded at GCE indicated that the Cu(II) species was reduced to Cu(0) through a Cu(I) state in which a disproportionation reaction of "2Cu(I)→Cu(0)+Cu(II)" occurred. A single oxidative stripping peak of "Cu→Cu(II)+" 〖"2e" 〗^"-" was observed in the anodic scan.
Cupric oxide and lead oxide were co-dissolved in Hbet-TFSI/H2O and the voltammetric behavior of Cu(II)/Pb(II) was studied. The corresponding cyclic voltammograms showed that separated redox couples of copper and lead could be observed, and the underpotential deposition (UPD) wave of lead on copper surface could be observed in front of the bulk deposition wave of lead.
Cu and CuPb alloys were electrodeposited at various deposition potentials with various temperatures using SSE as the substrate, and the surface morphology and compositions of the electrodeposits on SSE were observed by using scanning electron microscopy (SEM) and elemental semi-quantitative analysis (EDX), respectively. Highly pure Cu(s) was obtained by using electrodeposition on SSE. CuPb alloys were also successfully obtained by using electrodeposition from the solution containing copper and lead. The morphologies of the electrodeposited copper were likely dendritic, and those of CuPb alloys were flower cluster. Powder X-ray diffraction (XRD) patterns of the copper electrodeposits showed the presence of crystalline Cu with (111) favorable facet. The XRD patterns of CuPb alloys showed amorphous characteristics but copper and lead crystal signals could be observed individually when the co-deposits were obtained at relatively negative potential under 40°C.
The electrodeposited Cu and CuPb alloys were subjected to electrocatalytic studies towards the reduction of nitrate and the oxidation of glucose in pH 5 PBS and in 0.1 M NaOH(aq), respectively. To both reactions, SSE/Cu86Pb14(-0.12V,40°C) showed the highest current density, catalytic activity and stability.

並列關鍵字

ionic liquid ； copper oxide ； electrodeposition ； nitrate reduction ； glucose oxidation

參考文獻

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