Electrodeposition of manganese and molybdenum mixed oxide thin films and their charge storage properties
Electrodeposition of manganese and molybdenum mixed oxide thin films and their charge storage properties
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DOI：
10.1021/la050114u
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发表时间：
2005-06-21
期刊：
影响因子：
3.9
通讯作者：
Ogura, K
中科院分区：
文献类型：
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作者：
Nakayama, M;Tanaka, A;Ogura, K
通过在含有钼酸根阴离子 (MoO42-) 的锰 (II) 水溶液中，将电极电势相对于 Ag/AgCl 在 0 至 +1.0 V 之间循环，将薄膜形式的锰和钼混合氧化物阳极沉积在铂基底上。成膜的可能机制如下。首先，Mn2+离子与H2O发生电氧化，产生Mn氧化物和质子。然后，在电极表面附近积累的质子与MoO42-反应，通过脱水缩合反应（通过质子化和脱水）形成多钼氧酸盐。缩合物与Mn氧化物共沉淀。 Mn/Mo 氧化物薄膜涂覆的电极在 0.5 M Na2SO4 水溶液中的循环伏安法显示出赝电容行为，与类似制备的纯 Mn 氧化物相比，具有更高的电容和更好的倍率性能，很可能是由于薄膜电导率增加的结果。电化学石英晶体微天平和X射线光电子能谱清楚地表明，观察到的赝电容行为是由于水合质子的可逆提取/插入以平衡薄膜中Mn3+/Mn4+氧化/还原时的电荷所致。
Manganese and molybdenum mixed oxides in a thin film form were deposited anodically on a platinum substrate by cycling the electrode potential between 0 and +1.0 V vs Ag/AgCl in aqueous manganese(II) solutions containing molybdate anion (MoO42-). A possible mechanism for the film formation is as follows. First, electrooxidation of Mn2+ ions with H2O Yields Mn oxide and protons. Then, the protons being accumulated near the electrode surface react with MoO42- to form polyoxomolybdate through a dehydrated condensation reaction (by protonation and dehydration). The condensed product coprecipitates with the Mn oxide. Cyclic voltammetry of the Mn/Mo oxide film-coated electrode in aqueous 0.5 M Na2SO4 solution exhibited a pseudocapacitive behavior with higher capacitance and better rate capability than that of the pure Mn oxide prepared similarly, most likely as a result of an increase in electrical conductivity of the film. Electrochemical quartz crystal microbalance and X-ray photoelectron spectroscopy clearly demonstrated that the observed pseudocapacitive behavior results from reversible extraction/insertion of hydrated protons to balance the charge upon oxidation/reduction of Mn3+/Mn4+ in the film.