纳米MnO2溶氧电极催化剂制备研究

纳米材料具有特殊的物理化学性能,发展迅速。具有催化功能的纳米二氧化锰材料更是在电催化领域应用广泛。文中采用通过溶胶-乳状液-凝胶法制备了纳米MnO2,探讨了不同的表面活性剂、凝胶剂(三乙胺)的用量对纳米MnO2形貌、粒径和分散性能的影响。随后,研究了不同催化剂含量对空气电极阴极性能的影响进行了研究,探讨了催化层的最佳工艺条件。研究表明:采用溶胶-乳状液-凝胶体系,在油∶溶胶为4∶1,乳状液∶三乙胺体积比为8∶3的条件下制备的纳米二氧化锰,其粒度基本在200 nm以下;采用该二氧化锰制备的空气电极,电极催化层的最佳工艺条件为:催化层中催化剂、活性炭、60%PTFE乳液、助剂的比例为3.0∶2.0∶6.82∶0.05.配合使用80目导电镍网骨架用,合适的防水透气层,在7 mol/L的KOH电解液中,氧还原电流密度最大,可达197.4 mA/cm2,可以形成最大的生氧量68.3 mL/min,性能稳定的溶氧制氧电极。

Synthesis of nano-manganese dioxide catalyst for oxygen diffusion electrode application

Nano-materials with special physical and chemical performance are developed rapidly during the past decades. Among numerous nano-materials, manganese dioxide （ MnO2 ） in nano-scale is widely applied in electrocata!ysis area. In this work, nano-MnO2 is prepared based on a Sol-emulsion-gel system. The influence of surfactant and gel（triethylamine） on the morphology, particle size and dispersity were investigated. Subsequently, the performance dependence of the air cathode electrode on the MnO2 catalyst fabrication processes and the catalyst content is studied, and the process conditions of catalyst layer are optimized. The results show that the size of prepared nano-MnO2 particles is mostly below 200 nm under the conditions of Sol-emulsion-gel system in the oil：Sol of4：1 and emulsion triethylamine volume ratio of 8： 3. The optimum fabrication conditions of electrode catalyst layer, using nano-MnO2 as air electrode,is fixing the ratio of the catalyst, activated carbon, 60% PTFE emulsion, and accessory in- gredient in the catalyst layer at 3.0： 2.0： 6.82： 0.05. Cooperated with 80 heads conductive nickel as network, suitable waterproof-breathable layer, the highest oxygen reduction current density of 197.4 mA/cm2 could be achieved in 7 mol/L of KOH solution as electrolyte. The electrode with stable performance could reach the maximum oxygen generating speed of 68.3 mL/min.