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Low-temperature synthesis of ultrasmall spinel Mn Co3-O4 nanoparticles for efficient oxygen reduction
Chinese Journal of Catalysis ( IF 16.5 ) Pub Date : 2020-12-01 , DOI: 10.1016/s1872-2067(20)63624-5
Chengxiang Shi , Sana Ullah , Ke Li , Wei Wang , Rongrong Zhang , Lun Pan , Xiangwen Zhang , Ji-Jun Zou

Abstract Spinel-type manganese-cobalt oxides have been regarded as important class of electrocatalysts for oxygen reduction reaction (ORR). However, they are usually synthesized through oxidation-precipitation under aqueous ammonia and then crystallization at high temperature (150–180 °C), which not only increases the energy consumption but also induces the growth of particles that is unfavorable for ORR. Herein, through a facile precipitation-dehydration method, ultrasmall spinel manganese-cobalt oxide nanoparticles (~5 nm) homogeneously dispersed on conductive carbon black (MnxCo3-xO4/C) were fabricated at low temperature (60 °C). And the bimetallic composite oxide (Mn1.5Co1.5O4/C) with cubic spinel structure and high Mn content exhibits remarkable enhancement of ORR activity and stability compared with single metal oxide (both Mn3O4/C and Co3O4/C). The essential reason for the enhancement of activity can be attributed to the presence of the mixed Mn3+ and Mn4+ cations in Mn1.5Co1.5O4/C. Moreover, the ORR activity of Mn1.5Co1.5O4/C is comparable to that of commercial 20 wt% Pt/C, and the relative current density only decreases 1.4% after 12 h test, exceeding that of Pt/C and most reported manganese-cobalt oxide electrocatalysts.

中文翻译:

超小尖晶石Mn Co3-O4纳米颗粒的低温合成用于高效氧还原

摘要 尖晶石型锰钴氧化物被认为是一类重要的氧还原反应(ORR)电催化剂。然而,它们通常通过在氨水下氧化沉淀合成,然后在高温(150-180°C)下结晶,这不仅增加了能量消耗,而且诱导了不利于ORR的颗粒生长。在此,通过简便的沉淀-脱水方法,在低温 (60 °C) 下制备了均匀分散在导电炭黑 (MnxCo3-xO4/C) 上的超小型尖晶石锰钴氧化物纳米粒子 (~5 nm)。和双金属复合氧化物(Mn1.5Co1. 与单一金属氧化物(Mn3O4/C 和 Co3O4/C)相比,具有立方尖晶石结构和高 Mn 含量的 5O4/C)表现出显着增强的 ORR 活性和稳定性。提高活性的根本原因可归因于Mn1.5Co1.5O4/C 中混合Mn3+ 和Mn4+ 阳离子的存在。此外,Mn1.5Co1.5O4/C 的 ORR 活性与商业 20 wt% Pt/C 相当,并且在 12 小时测试后相对电流密度仅下降 1.4%,超过 Pt/C 和大多数报道的锰- 氧化钴电催化剂。
更新日期:2020-12-01
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