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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。
In order to improve the catalytic reduction efficiency of MnO2, B i modified MnO2 was treated as a catalyst for oxygen reduction at 350 ℃, ammonium oxalate pore former and MWNTs as composite electrocatalyst. The working current density was 50 mA / cm2 (-200 mV). The microscopic morphological analysis of B i modified MnO2 showed that the crystal particle size was about 100 nm, and the particle size distribution was more uniform with a natural agglomeration appearance. The diameter of the agglomerate was in the range of 2-8 μm. The mechanism of oxygen reduction by B i -modified MnO2 is as follows: during the discharge process, due to the good reversible property of BO2-modified MnO2, the electronic gain-loss process of O2 on MnO2 is an instantaneous process rather than the lattice shift of MnO2 , Just proton-electron transfer. When hypoxia, MnO2 reduction reaction occurs before the lattice transformation.