MnO_2动态催化氧还原的研究

为了提高MnO2催化氧还原效率,采用B i改性MnO2经350℃高温处理后作为氧还原的催化剂,草酸铵造孔剂及MWNTs为复合电催化剂,氧电极可获得50 mA/cm2的工作电流密度(-200 mV)。B i改性MnO2的微观形貌分析表明,其晶体颗粒尺度约100 nm,且粒径分布较均匀,呈自然团聚外貌,团聚物直径在2~8μm。B i改性MnO2催化氧还原机理为:在放电过程中,由于B i改性的MnO2具有良好的可逆性能,因此O2在MnO2上发生的电子得失过程是瞬间过程,而不是MnO2的晶格转变,仅仅是质子-电子的传递。当缺氧时,MnO2发生还原反应,才会发生晶格转变。

Study on oxygen reduction with MnO2 dynamic catalyze

A new compound catalyst was used to improve the efficiency of oxygen electroreduction on the MnO_2 electrode,this compound catalyst mainly consisted MnO_2 modified with Bi after treating with 350℃,and(NH_4)_2Ac as pore-forming agent and MWNTs as assistant catalyst,the working current density on oxygen electrode was 50 mA/cm~2(-200 mV).The microcosmic morphology of MnO_2 modified with Bi was studied by SEM.The results found out that the scale of the MnO_2 grains has a size about 100 nm,the grains had a narrow size distribution and reunited,particle clusters has a size between 2 μm and 8 μm.The mechanism of the electrochemical reduction of oxygen on the MnO_2 modified with Bi was concluded.In a discharging process,because of MnO_2 modified with Bi having a high reversibility,the charge transfer step of O_2 on MnO_2 was a stage of proton-electron transfer,which was a transient step,but not a step of MnO_2 lattice transformation.The MnO_2 lattice transformation only occurred in a reduction process of MnO_2 under the condition of oxygen lack.