於此我們的實驗，選用快速又簡單的微波水熱的方式來合成二氧化錳，前驅物使用過錳酸鉀作為錳金屬來源，使其水熱於酸性溶液中(氯化氫)作化學反應，主要改變水熱之(1)溫度及(2)升溫速率兩者來控制二氧化錳之相與形貌，全部的實驗水熱時間皆為5分鐘的反應。材料特性部分，在溫度變因中是使用140 o C至200 o C做反應，由結果發現於低溫的140 o C會傾向形成δ相，形貌為花狀表面的微米顆粒，並參雜著些許奈米的棒狀；高溫於160oC -200oC則傾向形成α相之二氧化錳，形貌為奈米棒狀，並隨溫度的升高棒狀直徑增加，。在升溫速率變因於140 o C之樣品，形成的二氧化錳可被分為兩種，樣品5 及20 o C /min為較差結晶度的δ相二氧化錳，形貌為花狀顆粒與奈米棒狀，擁有比表面積分別為210.4 m2/g及114.9m2/g；樣品10 及40 o C /min為結晶度較佳的δ相二氧化錳，形貌為純花狀顆粒，比表面積分別為129.4 m2/g及114.3 m2/g；在升溫速率變因固定於200 o C之樣品，皆形成了α相的棒狀物，隨著升溫速率的增加棒狀物的直徑增加、長度縮短；棒狀的比表面積較低，皆介於25-30 m2/g。
電化學部分，取合成後之二氧化錳材料作為超級電容之電極材料，做循環伏安法、電化學電阻、循環壽命之電化學測試；條件為使用1M Na2SO4水溶液作為電解質，電位窗為-0.1-0.9V。溫度變因之樣品以140oC的δ-MnO2為最佳擁有175.5F/g電容值，其餘的α-MnO2 皆介於40-60F/g的低電容值，由於在花狀顆粒擁有明顯較高的比表面積。升溫速率變因於140 o C之 5 、 20 o C /min樣品，擁有最好的比電容值表現分別為201.7F/g 及175.5F/g，是由於較高的比表面積、較多的孔洞分布體積、較少的K離子比例於二氧化錳主體中。升溫速率於200 o C，由於棒狀α-MnO2其近乎無中孔洞的結構且比表面積相似而並無特殊表現。

Nanostructured MnO2 was synthesized using a simple and rapid (5min)microwave-assisted hydrothermal technique through the decomposition of KMnO4 in various hydrochloric acid conditions. The hydrothermal solution consisted of KMnO4
and HCl. The effects of hydrothermal temperature and ramp rate were addressed. The temperature was varied from 140 to 200 o C at a ramp rate of 20 o C /min. It was found
that a lower temperature favors the formation of flower-like δ-MnO2 while a higher temperature favors alfa-MnO2 nanorod. The flower-like δ-MnO2 has a higher specific surface area of 114.9 m2/g than the alfa-MnO2 nanorods (25-30 m2/g). The flower-like δ-MnO2 has a larger pore size of 2.13 nm than the alfa-MnO2 nanorods. At a fixed temperature of 140 o C, the ramp rate was varied from 5 to 40 o C /min and found two kinds of characteristic, 5 and 20 o C /min samples have poor crystallinity the morphology is flower and few whiskers. Samples 10 and 40 o C /min which have good crystallinity the
morphology is pure flower without whiskers. At a fixed temperature of 200 o C, the ramp rate was varied from 7 to 40 o C /min and found that the length and diameter of the MnO2 nanorod become shorter and larger with the raising ramp rate. The obtained MnO2 was made into electrodes for use in supercapacitors. The supercapacitors were evaluated using
cyclic voltammetry and electrochemical impedance spectroscopy in 1M Na2SO4 within potential window -0.1~0.9V. The samples at fixed temperature 140 o C, 5 and 20 o C /min
ramp rate which have flower and whiskers morphology obtain the best specific capacitance performance (201.7F/g and 175.5F/g) due to their high surface area, much more pore
volume structure, low K+ ion exist in matrix and even may be the poor crystallinity cause more water adsorption. The other effects of characteristics on the capacitance performance will also be addressed.

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