现场紫外-可见吸收光谱研究电解二氧化锰的还原过程

Study on Reduction Process of Electrolyic Manganese Dioxide in Situ by Ultraviolet-visible Absorption Spectroscopy

应用现场紫外 可见吸收光谱研究碱性溶液中电解MnO2(EMD)放电机理.结果表明,对EMD电极的放电还原,包括两个单电子过程,其第1电子还原又分为3步:①还原MnO2颗粒表面和阳离子空位附近的Mn4+离子,②还原斜方锰矿中的Mn4+离子,③还原软锰矿中的Mn4+离子.第2电子还原是将溶解的Mn3+还原成Mn2+,进一步转化成Mn(OH)2和Mn3O4.

The concentrationsof soluble Mn(Ⅲ) species,during the reduction ofelectrolytic MnO_(2) (EMD)in alkaline solution,have been monitored in situ by UV-visible spectroscopy. The concentration of Mn(Ⅲ) ion in solution changes with discharge time.The first electron discharge process of EMD can be described by three different steps: 1) the reduction of Mn^(4+)ions on the surface of EMD particles and the structural defect regions within the EMD,2) the reduction of Mn^(4+)ions in ramsdellite,3)the reduction of Mn^(4+)ions in pyrolusite. During the second electron discharge of EMD, the soluble Mn(Ⅲ) is reduced to Mn(Ⅱ) , then Mn(OH)_(2)and Mn_(3)O_(4)are formed.