Synthesizing Li-Al layered double hydroxide film on aluminum substrate by electrochemical deposition method in ambient atmosphere


本研究在常溫壓下將1050鋁基材(陰極)與不鏽鋼片(陽極)浸入含有鋁離子與鋰離子的鹼性水溶液中(pH 12.3),並於兩極間施加直流電壓(2 V DC),目標在1050鋁箔基材上迅速成長鋰鋁層狀雙氫氧化物(Li-Al-CO3 LDH)薄膜。鋁金屬是兩性的,在鹼性溶液中易受腐蝕。在本研究之電沉積法中,因為鋁材受到陰極保護的關係,基材表面因水解所導致的腐蝕現象及氫氣泡將不會發生。另外,因為本製程中並未使用金屬鹽類的關係,薄膜成品不需要水洗。傅立葉轉換紅外光譜儀(FT-IR)分析不同製程時間的樣品,發現經30秒表面處理的試片,其O-H in gibbsite layers (~3470 cm-1)訊號劇增;經100秒表面處理後,層間區域之H2O-CO32- (~3040 cm-1)訊號出現。在製程75秒至100秒間,非晶型的CO32-訊號由插層型的CO32-訊號取代;相似地,在製程10秒至100秒間,非晶型的OH groups訊號由結晶型的OH groups訊號取代。經過200秒電沉積處理後,所有典型代表Li-Al-CO3 LDH的訊號峰皆已出現。以上資訊說明,電沉積成長Li-Al-CO3 LDH薄膜概略的成長機構是:先成長帶正電的前驅物,隨後為正電層的發展,最後是負電層的發展。另外,FT-IR分析結果顯示LDH前驅物有隨時間轉變為結晶型LDH的現象。實驗結果指出,水是影響LDH前驅物轉變為結晶型LDH的主要因素。ABSTRACT (in Chinese) Ⅰ ABSTRACT (in English) Ⅱ LIST OF CONTENTS Ⅲ LIST OF TABLES Ⅳ LIST OF FIGURES Ⅴ CHAPTER 1 Introduction 1 CHAPTER 2 Experimental 5 2.1. Substrate material 5 2.2. Al3+- and Li+-containing electrolyte aqueous 5 2.3. Electrically driving the growth of LDH precursor and its transformation to crystalline film on Al substrate 6 2.4. LDH precursor film transforming to crystalline LDH film under different atmosphere 7 CHAPTER 3 Results and discussion 8 3.1. Li-Al-CO3 LDH thin film on Al substrate 8 3.2. The growth mechanism of the Li-Al-CO3 LDH thin film prepared by electrodeposition method 10 3.3. Examine the transformation of LDH precursor in four different atmosphere conditions 14 CHAPTER 4 Conclusions 18 REFERENCES 4

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