无机材料学报

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暖等离子体合成过渡金属掺杂氧化锰析氧电催化剂

李家琪1, 李小松1, 李煊赫1, 朱晓兵1,2, 朱爱民1   

  1. 1. 大连理工大学 等离子体物理化学实验室,大连 116024;
    2. 大连理工大学 氢能与环境催化中心,大连 116024
  • 收稿日期:2023-11-24 修回日期:2024-02-06
  • 作者简介:李家琪(1999-), 女, 硕士研究生. LI Jiaqi (1999-), female, Master candidate.
  • 基金资助:
    国家自然科学基金(22278052) National Natural Science Foundation of China (22278052)

Transition Metal-doped Manganese Oxide: Synthesis by Warm Plasma and Electrocatalytic Performance for Oxygen Evolution Reaction

LI Jiaqi1, LI Xiaosong1, LI Xuanhe1, ZHU Xiaobing1,2, ZHU Aimin1   

  1. 1. Laboratory of Plasma Physical Chemistry, Dalian University of Technology, Dalian 116024, China;
    2. Center for Hydrogen Energy and Environmental Catalysis, Dalian University of Technology, Dalian 116024, China
  • Received:2023-11-24 Revised:2024-02-06

摘要: 可再生能源发电与质子交换膜水电解结合产生“绿色氢”,其速控步骤是析氧反应。从稳定性、活性和成本角度考虑,本研究采用滑动弧暖等离子体一步合成了氧化锰(MnOx)及过渡金属掺杂(Fe-MnOx,Co-MnOx,Ni-MnOx)的析氧电催化剂,并对其晶体结构、形貌尺寸、元素组成和表面价态进行了表征。氧化锰主要由晶相Mn2O3和无定形Mn3O4组成。与之相比,掺杂的氧化锰尽管晶相组成基本不变,但其粒径明显变小、比表面积增大。掺杂Co促使氧化锰的表面电子增多。氧化锰基催化剂在(酸性电解液)循环伏安测试中表现出独特的电流阶跃现象(低电势Ⅰ-Ⅱ区: 1.4-1.8-2.4 V; 高电势Ⅲ区: 2.4-2.7 V)。该电流阶跃过程与Bulter-Volmer简化方程的电极动力学参照曲线相吻合,属于多价锰参与的电催化行为。低电势区Fe-MnOx的电化学活性最优,而高电势区Co-MnOx表现最优。Co-MnOx的起始电位较MnOx低160 mV,且在恒电位电解中其末端电流是MnOx的3倍。与其活性趋势一致,Fe-MnOx、Co-MnOx分别在低电势区、高电势区更具稳定性。本研究通过掺杂过渡金属优化氧化锰的颗粒尺寸、比表面积和电子结构,从而显著提高析氧反应活性及稳定性。

关键词: MnOx, 过渡金属掺杂, 电流阶跃现象, 析氧反应, 滑动弧等离子体

Abstract: Using renewable electricity proton exchange membrane (PEM) water electrolysis can produce “green hydrogen”, for which the rate-determining step is oxygen evolution reaction. Considering the problems of stability, activity and cost, manganese oxides (MnOx) doped with transition metals as electrocatalysts (Fe-MnOx, Co-MnOx, Ni-MnOx) were one-step synthesized using warm plasma of gliding arc. Complementary characterizations of the crystal structure, morphology, element composition, and surface valence state on the synthetic catalysts were conducted. MnOx mostly consists of crystalline Mn2O3 and amorphous Mn3O4. Although the transition metal doped catalysts possess the very approximate crystalline compositions to MnOx, a remarkable decrease in particle size and an increase in surface area relative to MnOx were detected. Introducing Co (of Co-MnOx) promoted an increase in surface density of electrons compared to MnOx. This work identified a unique current step on MnOx-based catalysts in acidic medium, which appeared at three consecutive potential regions (low Ⅰ-Ⅱ: 1.4-1.8-2.4 V; high Ⅲ: 2.4-2.7 V) for cyclic voltammetry (CV) measurements. This current step process is quite consistent with the electrode dynamics curve (as reference) using a simplified version of Bulter-Volmer equation, and the electrocatalytic behavior involves in the manganese of multi-valence states. At low potential regions Fe-MnOx

Key words: MnOx, transition metal doping, current step, oxygen evolution reaction, gliding arc plasma

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