二元层状钴掺杂锰氧化物的制备及电催化性能研究

Preparation and Electrocatalytic Performance of Binary Layered Cobalt-Doped Manganese Oxide

摘要: 锰在地球上的储量丰富、毒性低，且其层状结构具有强可调性，具备巨大的应用潜力。然而不恰当的电子结构和较低的导带水平阻碍了其在电催化水裂解中的应用，缺陷工程是提高MnO电子电导率和电化学性能的重要策略。本文以层状二氧化锰为基体，通过固相烧结掺杂不同比例钴元素制备了一系列二元锰钴氧化物，作为非贵金属OER催化剂。其中Mn_0.5Co_0.5O₂二元层状锰钴氧化物材料在10 mA∙cm⁻²处表现出最佳性能，过电势降低至380 mV，Tafel斜率低至55 mV∙dec⁻¹，优于锰钴单金属氧化物催化剂以及其他二元层状锰钴氧化物。外源元素掺杂提高了本征电子电导率，增加氧化还原活性中心浓度，加速离子扩散和电荷存储转移，从而达到降低过电位的目的。

Abstract: Manganese is abundant on the earth, because of its low toxicity and strong adjustable layer struc-ture; it has huge application potential. However, improper electronic structure and low conduction band level hinder its application in electrocatalytic water splitting. Defect engineering is an important strategy to improve the electronic conductivity and electrochemical performance of MnO₂. In this paper, a series of binary manganese cobalt oxides were prepared by solid-phase sintering doped with different proportion of cobalt on layered manganese dioxide as non-noble metal OER catalyst. The Mn_0.5Co_0.5O₂ binary layered manganese cobalt oxide material shows the best performance at 10 mA∙cm⁻², with overpotential reduced to 380 mV and Tafel slope as low as 55 mV∙dec⁻¹, which is better than the single metal oxide catalyst and other binary layered oxides. Exogenous element doping improves the intrinsic electronic conductivity, increases the concentration of redox active centers, accelerates ion diffusion and charge transfer, and thus achieves low overpotential.