由聚苯胺氧化還原催化特性所感應生成之鈍性氧化層Fe2O3在氣體感測上之應用研究

本文的研究主軸是透過導電高分子聚苯胺（Polyaniline, PANI）的「可逆氧化還原」能力將鐵片表面氧化以形成一緻密的鈍性氧化層（γ-Fe2O3/Fe3O4），並利用「磁性的差異」將γ-Fe2O3分離出來並進行後續高溫處理（550°C煅燒 6小時），將晶格轉換成α-Fe2O3。接著，對所製備的γ-Fe2O3及α-Fe2O3兩種不同晶型的材料進行氣體感測元件的應用研究。本篇內容可細分為三個部分，第一部分：以傳統的氧化聚合法合成PANI，之後將其溶解在有機溶劑NMP中（濃度：1 wt%）並將其塗佈在鐵片上，於通風櫥中利用加熱器（加熱溫度至50°C）以去除溶劑，之後於室溫下靜置大約為30天。在PANI塗料及金屬鐵接觸的界面，具可逆氧化還原能力的PANI在30天的時間內可將鐵片「氧化」形成緻密的鈍性氧化層，而PANI本身會被「還原」。鐵片的被氧化及PANI的被還原可個別的經由X射線光電子能譜（XPS）及紅外光譜（FTIR）加以確定。第二部分：首先利用溶劑NMP將PANI塗層自鈍性氧化層上去除，之後並將鈍性氧化層（γ-Fe2O3/Fe3O4）自鐵片上刮下，並進一步將其研磨成粉末狀，接著利用磁鐵將「具有磁性」的Fe3O4及「不具磁性」的γ-Fe2O3進行分離。所分離出的γ-Fe2O3經過高溫煅燒處理將其晶格結構轉換成α-Fe2O3，然後以X光繞射儀（XRD）鑑定煅燒後α-Fe2O3的晶格結構，並且以化學分析電子能譜儀（XPS）檢測其元素成分。最後的第三部分：將煅燒前、後的γ-Fe2O3及α-Fe2O3應用在氣體感測元件比較性檢測，並研究其靈敏度、重複性、穩定性及選擇性數據。從研究結果顯示：由此方法所製備的γ-Fe2O3無法直接應用在氣體感測元件上。而經過高溫鍛燒處理過的α-Fe2O3 則可應用在硫化氫氣體感測元件上。

關鍵字

聚苯胺；可逆氧化還原；鈍性氧化層； α-Fe2O3 ；氣體感測；硫化氫

並列摘要

The main research focus of this paper is to oxidize the surface of the iron sheet to form a dense passive oxide layer (γ-Fe2O3/Fe3O4) through the "reversible redox" ability of the conductive polymer polyaniline (PANI). The as-prepared γ-Fe2O3 performs subsequent high temperature treatment (calcination at 550°C for 6 hours) to convert the lattice into α-Fe2O3. Next, the application research of gas sensing element is carried out on the prepared materials of γ-Fe2O3 and α-Fe2O3 with two different crystal forms. The content of this article can be subdivided into three parts, the first part: Synthesis of PANI by traditional oxidative polymerization method, then dissolving it in organic solvent NMP (concentration: 1 wt%) and coating it on iron sheet, in ventilation a heater (heating temperature ~ 50°C) was used in the cabinet to remove the solvent and then left to stand at room temperature for about 30 days. At the interface between PANI coating and metallic iron, PANI with reversible redox ability can "oxidize" iron sheets to form a dense passive oxide layer within 30 days, while PANI itself will be "reduced". The oxidation of iron flakes and the reduction of PANI can be determined by X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR), respectively. Part II: First, the PANI coating was removed from the passive oxide layer using solvent NMP, then the passive oxide layer (γ-Fe2O3/Fe3O4) was scraped off the iron sheet, and further ground into powder, then the "magnetic" Fe3O4 and the "non-magnetic" γ-Fe2O3 are separated by a magnet. The isolated γ-Fe2O3 was calcined at high temperature to convert its lattice structure into α-Fe2O3, and then the lattice structure of α-Fe2O3 after calcination was identified by X-ray diffraction (XRD), and the electronic energy spectrum was analyzed by chemical analysis instrument (XPS) to detect its elemental composition. Finally, the third part: γ-Fe2O3 and α-Fe2O3 before and after calcination were applied in the comparative detection of gas sensing elements, and their sensitivity, repeatability, stability and selectivity were studied. The research results show that the γ-Fe2O3 prepared by this method cannot be directly applied to the gas sensing devices. The α-Fe2O3 that has been calcined at high temperature can be applied to the H2S gas sensing element.

並列關鍵字

Polyaniline ； Reversible redox ； Passive oxide laye ； α-Fe2O3 ； Gas sensing ； Hydrogen sulfide

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