消毒溶液的使用相當廣泛，在醫院與食品工業上尤其重要，因此為符合環保標準，對於在消毒液使用後的排放監測就顯得相當重要，本研究嘗試多種方式製備具有寬電化學電位窗和低背景電流等優越電化學特性的類鑽碳，作為工作電極，以研發電流式消毒液感測器。主要以消毒液成份之一的醋酸作為示範偵測物，因醋酸反應力較弱，若電極可偵測醋酸，則偵測其它消毒物質的可行性也大增。醋酸之外，已可成功偵測應用於醫院之多種消毒劑如酒精、甲醛、過氧化氫、過氧醋酸等，還具有精確、快速、經濟、可微小化、簡單等優點，極具發展潛力。
　　實驗於檸檬酸鈉水溶液進行，以濺鍍法製備類鑽碳，並對製備條件與感測作探討，尋求最佳感測之製備條件。在工作電極施予所需之還原電位下，醋酸會在電極表面產生還原反應，使電流發生變化而獲得感測訊號，而感測電流與濃度成正比關係，實驗結果發現最佳濺鍍參數為70W濺鍍功率、-100V或以上之基材偏壓，靈敏度可達4.488A/cm2-ppmHAc。若對電極作低溫鍛燒處理，可有效提高電極靈敏度，最佳鍛燒溫度為200oC下處理一小時，對70W功率與-100V偏壓之類鑽碳來說，靈敏度可提昇至6.74A/cm2-ppmHAc，線性度維持良好，迴歸之R2大於0.99。濺鍍類鑽碳電極可偵測12～300ppm之醋酸，平均應答時間5秒，攪拌速率在60rpm可有最平穩背景電流與最佳應答電流，在連續使用超過18小時後，電極開始不穩定，感測電流會有忽大忽小的情形發生。
濺鍍類鑽碳電極以拉曼光譜分析結構發現，靈敏度佳的電極其ID/IG比值小，比值在1左右，比值越小表示sp3含量越多，而相對地sp2含量越少，本實驗類鑽碳之sp3含量最高可達11.5%。而ID/IG強度比較小者，G band位置同時往低處偏移，最低降至1577cm-1，且D band與G band之間也隨sp3含量，由最大231間距縮小至216 cm-1，兩峰互相靠近的情形表示混成結構增加，使類鑽碳特性越趨明顯，研究結果顯示，電極靈敏度與sp3含量息息相關。
　　除了濺鍍法外，還使用熱解方法，以高分子溶液製備類鑽碳，以700oC熱解的類鑽碳靈敏度最佳，在60～5000ppm醋酸的範圍內，平均靈敏度為4.423 A/cm2-ppmHAc。熱解溫度低於500oC的厚膜使導電度極差，無法作感測，但熱解溫度高於700oC則會使高子中的氧原子攜帶碳而逸出，使白金基材參與作用，拉曼光譜圖的二峰距與強度比也確定，當熱解溫度提高，會給予碳原子重排的能量，使其規則排列，即石墨化。
　　另外嘗試以電鍍法製備類鑽碳，但附著力差，無法作電化學使用，其拉曼光譜圖亦顯示其以石墨結構為主導。
　　在反應控制系統，對類鑽碳工作電極而言，由理論求得應答電流與醋酸濃度的關係式為：
(I-1)
　　其中，K5、K6、K10、為常數，當CG遠大於CA時，應答電流可視為線性。
　　而在擴散控制系統方面，當攪拌速率在100 rpm以下時，由理論推導出感測電流與醋酸濃度關係式為：
(I-2)
　　其中n、F、A、D0均為常數，由實驗值可求擴散係數為2.1410-9 m2/s。攪拌速率超過150rpm，靈敏度降低，因速率決定步驟已非醋酸的擴散。

　Disinfectants and sterilants are widely used, especially needed in hospital and food industry. In order to make effluents environmentally benign, the monitor of disinfectant effluent is quite essential. This study is focusing on amperometric sensor for disinfectant detection at diamond-like carbon working electrode, which has been scientifically proved to possess outstanding electrochemical behavior such as extraordinary wide electrochemical potential window and extremely low background current. Acetic acid was set as model analyte, for it is less reactive on a reduction and oxidation basis. The probability of detecting other disinfectants prospers if the electrode is sensible to acetic acid. It has been achieved in this study that apart from acetic acid, the electrode works, too, on such hospital disinfectants as alcohol, formaldehyde, hydrogen peroxide, and peracetic acid. Among all analytical methods, direct electrochemical analysis makes the accurate, the most convenient, the simplest and the fastest response possible, and miniaturization as well.
　The best preparing conditions and best sensing behavior of sputtered DLC were the major issue in this study. In sodium citrate aqueous solution, Acetic acid reduced on the surface of the DLC working electrode at a specific applied potential. The reduction of acetic acid generated a sensing current in positive proportion to the concentration of acetic acid. It turned out that the best sputtering power was 70W and substrate applied voltage above -100V. The sensitivity of DLC with this fabrication condition was 4.488A/cm2-ppmHAc. Processing with one-hour annealing was found to effectively improve electrode performance. The best annealing temperature was 200oC. For example, the sensibility of a 70W-sputtered and -100V-biased DLC was elevated to 6.74A/cm2-ppmHAc and still had excellent linearity R2 value larger than 0.99. A sensing range from 12 to 300ppm acetic acid had been carried out on sputtered DLC with an average response time of 5 seconds. Stirring rate had better be kept at 60 rpm to reach the steadiest background current and best response current. Long-term stability test showed that this electrode started to act unsteadily and uncontrollably after 18 hours continuous sensing.
　Inspecting the electrode structure by Raman spectroscopy, the one with the best sensitivity had the smallest ID over IG ratio of values very close to 1, which represented a major content of sp3 structure as highest as 11.5% and thus a least content of sp2 structure. Where there was smaller ID over IG ratio, there was a down shift of G band as lowest as 1577 cm-1 and hence resulted in a shrink of band difference from 231 to 216 cm-1. The closer the two peaks, the more hybridized the DLC was, which featured more diamond-like. It was shown clearly that electrode sensitivity was unbelievably closely related to its sp3 content, viz. ID/IG intensity ratio.
　Other than sputtering, the second fabrication method was pyrolysis where DLC was sintered out of PVA polymer solution. A 700oC pyrolytic DLC brought forth the best sensitivity of 4.423 A/cm2-ppmHAc within the acetic acid range of 0 ~ 5000 ppm. Pyrolytic temperature less than 500oC contributed to scanty conductivity and accordingly to detect electrochemically meet difficulty. The O in the polymer escaped along with C at pyrolytic temperature higher than 700oC and consequently Pt conducting substrate participated in the sensing process. Raman spectroscopy affirmed, by intensity ratio and band difference, that temperature upgrade provided energy for carbon atoms to re-arrange towards graphitization.
　Still, there was one more method to fabricate DLC, a new method in an electrochemical way called electolysis, a.k.a. electroplating. Such DLC showed poor adhesion bonding to substrate so that it could not be electrochemically utilized any further. Its Raman spectrum reported that the main structure of electrolytic DLC was actually sp2 graphite structure.
　For sputtered DLC working electrode in a reaction-controlled system, the theoretical relation between response current and acetic acid concentration can be expressed as:
(I-1)
　where K5, K6, K10, and  are constants. Supposing CG is far larger than CA, the response current can be considered as linear to analyte concentration.
　On the other hand, for sputtered DLC working electrode in a diffusion-controlled system, which was considered possible when stirred at less than 100rpm, the theoretical relation between response current and acetic acid concentration can now be expressed as:
(I-2)
　where n, F, A, D0 are constants.
　Putting experimental results into the above function comes to the diffusion coefficient of 2.1410-9 m2/s. At stirring rate larger than 150rpm, raising stirring rate did not increase sensitivity any longer since the rate determining step was no longer the diffusion of acetic acid.

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