本研究以硝酸鈷為前驅物，氫氧化鈉為沉澱劑，空氣為氧化劑，
採用沉澱-氧化法搭配水熱程序製備不同氧化態的氧化鈷(CoOX)系
列產物，並以X光繞射、程溫還原、熱重分析、電子顯微鏡等技術
分析樣品的性質。更進一步地將所合成的CoOOH應用在金屬氧化物
半導體型CO氣體感測器上當感測材料。
從實驗結果可得知，CoOX的氧化態可藉由沉澱溶液的pH值來加以
控制；當pH＜9時，CoOX主要成份是Co3O4；9＜pH＜14時，主要成
份則是CoOOH；但是當pH＞14時，Co3O4及Co(OH)2變成CoOX的主體。
以製備CoOOH當半導體式CO氣體感測器的感測材料，其對CO的靈
敏度以80℃為最高(S = 5.6)，其響應時間(response time)約為1
分鐘。和Co3O4相比較，CoOOH有較佳的靈敏度，且可偵測的最低濃
度約為1 ppm(S/N＝12)。CoOOH有不錯的CO選擇性(Sco/SH2~4)，不
易受到其他干擾性的氣體影響。與文獻上之其它金屬氧化物相比較
，CoOOH有較低的操作溫度(~80℃)。

Cobalt oxides (CoOx) of different oxidation states were prepared from Co(NO3)2 solution through a precipitation with NaOH and oxidation by air. The prepared samples were characterized with techniques of X-ray diffraction (XRD), temperature-programmed reduction (TPR), thermal analysis (TG) and electron microscopy. Furthermore, we applied CoOOH for sensing materials of SCS CO sensors.

From experimental results, we can find that : The oxidation state of cobalt oxides(CoOX) can be controlled by pH value . Co3O4 was the main product at pH < 9. CoOOH dominated at 9 < pH < 14, but the product became Co3O4 and Co(OH)2 at pH > 14.

In SCS, the optimum working temperature of CO detection was about 80 oC (S = 5.6). The response time SCS based on CoOOH was short (~1 min). CoOOH has better sensitivity than Co3O4 and can detect low CO down to 1 ppm(S/N＝12). CoOOH has a high selectivity of CO relative to H2(Sco/SH2~4). The optimum working temperature(~80 oC) of CoOOH is lower than other semiconductor oxides on reviews.

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