Tunable Bifunctional Activity of Mnx Co3-x O4 Nanocrystals Decorated on Carbon Nanotubes for Oxygen Electrocatalysis.,ChemSusChem

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Tunable Bifunctional Activity of Mnx Co3-x O4 Nanocrystals Decorated on Carbon Nanotubes for Oxygen Electrocatalysis.
ChemSusChem ( IF 7.5 ) Pub Date : 2018-03-26 , DOI: 10.1002/cssc.201800049
Tingting Zhao ₁ , Srinivas Gadipelli ₁ , Guanjie He ₁ , Matthew J Ward ₂ , David Do ₃ , Peng Zhang ₃ , Zhengxiao Guo ₁

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Noble-metal-free electrocatalysts are attractive for cathodic oxygen catalysis in alkaline membrane fuel cells, metal-air batteries, and electrolyzers. However, much of the structure-activity relationship is poorly understood. Herein, the comprehensive development of manganese cobalt oxide/nitrogen-doped multiwalled carbon nanotube hybrids (Mnx Co3-x O4 @NCNTs) is reported for highly reversible oxygen reduction and evolution reactions (ORR and OER, respectively). The hybrid structures are rationally designed by fine control of surface chemistry and synthesis conditions, including tuning of functional groups at surfaces, congruent growth of nanocrystals with controllable phases and particle sizes, and ensuring strong coupling across catalyst-support interfaces. Electrochemical tests reveal distinctly different oxygen catalytic activities among the hybrids, Mnx Co3-x O4 @NCNTs. Nanocrystalline MnCo2 O4 @NCNTs (MCO@NCNTs) hybrids show superior ORR activity, with a favorable potential to reach 3 mA cm-2 and a high current density response, equivalent to that of the commercial Pt/C standard. Moreover, the hybrid structure exhibits tunable and durable catalytic activities for both ORR and OER, with a lowest overall potential of 0.93 V. It is clear that the long-term electrochemical activities can be ensured by rational design of hybrid structures from the nanoscale.

中文翻译：

碳纳米管修饰的 Mnx Co3-x O4 纳米晶体用于氧电催化的可调节双功能活性。

不含贵金属的电催化剂对于碱性膜燃料电池、金属空气电池和电解槽中的阴极氧催化具有吸引力。然而，人们对许多结构-活性关系知之甚少。在此，报道了锰钴氧化物/氮掺杂多壁碳纳米管杂化物（Mnx Co3-x O4 @NCNTs）的综合开发，用于高度可逆的氧还原和析出反应（分别为ORR和OER）。通过精细控制表面化学和合成条件，合理设计杂化结构，包括表面官能团的调节、相和粒径可控的纳米晶体的一致生长，以及确保催化剂-载体界面之间的强耦合。电化学测试揭示了混合材料 Mnx Co3-x O4 @NCNT 之间明显不同的氧催化活性。纳米晶 MnCo2 O4 @NCNTs (MCO@NCNTs) 杂化物表现出优异的 ORR 活性，具有达到 3 mA cm-2 的良好潜力和高电流密度响应，相当于商业 Pt/C 标准。此外，该杂化结构对 ORR 和 OER 均表现出可调且持久的催化活性，最低总电势为 0.93 V。很明显，通过从纳米尺度合理设计杂化结构可以确保长期电化学活性。

更新日期：2018-03-26

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