自催化生长MnCr2O4纳米线及其对ORR/OER的抑制效应

Self-catalyzed Growth of MnCr2O4 Nano wires and Their Inhibitory Effect on ORR/OER

还原性气氛下在商品化导电不锈钢网筛的表面上合成了具有尖晶石单晶结构的MnCr2O4纳米线.在Ar/H2混合气体中,1100~1200℃条件下,对这些不锈钢网筛衬底进行热退火.电子显微镜研究表明,通过控制温度和生长时间,这些纳米线的直径在50~100 nm范围内,长度为1~10μm.文章提出一种可能的自催化机制来解释这些MnCr2O4纳米线的生长,并研究了这些纳米线负载在不锈钢网筛上对非水锂空气电池的氧还原(ORR)和氧析出(OER)反应的影响,发现其对ORR/OER反应具有抑制作用.该抑制作用与不同热退火温度导致的不同表面积相关.研究结果有助于帮助了解作为锂空气电池的空气电极导电衬底上的表面纳米结构与其电化学性能之间的关系.

This paper describes a vapor-phase approach to the facial synthesis of spinel single-crystalline MnCr2O4 nanowires supported on the surfaces of commercial conducting stainless steel mesh substrates under a reducing atmosphere.A typical procedure simply included the thermal annealing of these substrates in Ar/H2 mixed gas and within the temperature range from 1100 to 1200℃.Electron microscopic studies indicated that these nanowires have a diameter within the range of 50-100 nm and lengths of 1-10μm by varying the temperature and growth time.A possible self-catalyzed mechanism was proposed to account for the growth of these MnCr2O4 nanowires.The effect of these nanowires supported on stainless steel mesh on non-aqueous Li-air batteries was also studied.The effect was found to be dependent on surface areas,which resulted from annealing temperatures.The results of this work help us understand the relationship between the surface nanostructures on conducting substrates as air electrode of Li-air batteries and their electrochemical performances.