氧化釕薄膜之連續式離子層吸附與反應法製備及其鑑測與電化學應用

Abstract

本篇論文主要目的在於探討以連續式離子層吸附與反應法製備具電化學偵測能力之氧化釕薄膜。連續式離子層吸附與反應法已被廣泛地應用於過渡金屬的VI A族化合物製備，特別是硫化物和氧化物薄膜的製備。通常製備時，基材表面循環交替浸泡於陽離子溶液和陰離子溶液中，以形成無機金屬化合物的薄膜。並透過增加循環的次數，來控制薄膜的厚度。此方法最大的優點就是製備過程簡易，可藉由控制反應次數調整薄膜厚度，且所製得之薄膜較不受基材面積限制。本篇論文特別選擇釕的氧化物做為連續式離子層吸附與反應法的製備對象。由於二氧化釕在常溫常壓下相當穩定，其導電性優於一般的金屬氧化物，且對特定氧化反應具催化活性，所以在鹼氯工業上常被用為陽極鍍膜，以製備氯氣。此外，二氧化釕也常被用為電容材料或半導體工業的電極材料等。 本論文研究的主要方向，乃藉由控制熱、雙氧水、鹼等反應條件，來改變陰離子前驅液的組成，並改變基材，以探討其對所製得之氧化釕薄膜的化學組成、表面型態、電化學偵測的影響。其中，化學組成的研究，主要是利用X光電子能譜儀以及二次離子質譜儀做定性的分析；表面形態的研究，主要是利用場發射掃描式電子顯微鏡，觀察各種條件對於薄膜表面形態的影響。在電化學偵測上，本論文研究主要選用維生素C、對乙醯氨基酚、多巴胺為標的分析物，利用在不同條件下所製得之氧化釕薄膜的修飾電極，於定電位的模式下分別建立穩定電流值對分析物濃度的檢量線，以了解不同電極對各標的分析物的偵測能力，並透過X光電子能譜儀以及二次離子質譜儀鑑定該電極偵測前後其表面之變化，以探討偵測能力變化之化學成因。

Successive ionic layer adsorption and reaction (SILAR) method has been widely used in the synthesis of group VIA compounds of metals, such as oxides, sulfides, and selenides. It involves cycles of alternate dipping of a substrate into two separate solutions, which are made of a cation precursor and an anion precursor, respectively, and results in the formation of thin films for the intended compound. The thickness of the film formed can be controlled through adjusting the number of reaction cycles. The film synthesized is not limited by the macroscopic area of the substrate. The SILAR method is easy to control, simple, less expensive, and uses less organic solvents. In this thesis research, we studied the chemistry involved in the SILAR synthesis of ruthenium oxide (RO) films on silicon and indium tin oxide (ITO) substrates. The driving forces that determine the formation of RO films are known to include the presences of moderate oxidizing agent and hydroxide ion in the solution as well as heat. In the study, the cation precursor was ruthenium (III) chloride and the anion precursor was generated in the solution via manipulating the driving forces mentioned above. The RO thin films synthesized were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). The XPS spectra revealed that a stronger oxidizing condition favored the formation of RO films having higher oxidation states of ruthenium and a basic condition caused a hydroxide phase to become dominate.

The use in electrochemical sensing of the ITO substrates that were modified by RO films (termed RO/ITO herein) was investigated by using RO/ITO as the working electrode in a three-electrode system for detection of some molecules, such as vitamin C, acetaminophen, and dopamine, in 0.1 M phosphate buffer solutions of pH 7.0. Cyclic voltammograms, chronoamperograms, and the calibration curves for sensing these molecules were established. The RO/ITO electrode prepared under the condition of 1％ H2O2 solution gave the best sensitivity for vitamin C detection, the one made at 60℃ in DI water displayed the largest sensitivity for acetaminophen detection, whereas the electrode fabricated under sodium hydroxide solution of pH 12 offered the greatest sensitivity for dopamine detection. All RO/ITO electrodes made under different oxidizing agent/pH/heat conditions showed a better sensitivity for the detection of dopamine than that of vitamin C and acetaminophen.