Prussian blue analogue-derived Mn–Fe oxide nanocubes with controllable crystal structure and crystallinity as highly efficient OER electrocatalysts

• Published in: Journal of alloys and compounds 2020-04, Vol.820, p.153438, Article 153438
• Main Authors: Ma, Quanyin, Dong, Rui, Liu, Heng, Zhu, Anquan, Qiao, Lulu, Ma, Yongjin, Wang, Juan, Xie, Jianping, Pan, Jun
• Format: Article
• Language: English
• Subjects: Bimetals; Catalysts; Crystal structure; Crystallinity; Electrocatalyst; Electrocatalysts; Iron oxides; Manganese; Mn–Fe oxides; Morphology; Oxidation; Oxides; Oxygen evolution reaction; Oxygen evolution reactions; Pigments; Precursors; Prussian blue analogous; Pyrolysis; Synergistic effect; Water splitting
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.153438

A series of ternary manganese iron oxides with different crystal structures, oxidation states and crystallinities were successfully fabricated by modulating the calcination conditions of Mn–Fe Prussian blue analogue (PBA) precursor (Mn3 [Fe(CN)6]2·nH2O). The obtained Mn–Fe oxides retained the nanocubic morphology of the PBA precursor, and a mesoporous structure was acquired as a result of gas molecule release during the pyrolysis process. Electrochemical oxygen evolution reaction (OER) activity of the as-prepared catalysts was tested, and among the bimetallic oxides, the catalyst that had a crystal structure similar to cubic bixbyite Mn1.2Fe0.8O3 (space group: Ia-3) with low crystallinity exhibited the most advanced OER activity. An overpotential of only 245 mV was required to achieve a current density of 10 mA cm−2, and the Tafel slope value was only 38 mV dec−1. The excellent OER activity is likely due to the hollow porous morphology of the samples, the synergistic effect of Mn and Fe, the defect-rich low crystallinity of the catalyst, and the cubic Mn1.2Fe0.8O3 structure (space group: Ia-3), which has an intrinsic activity superior to that of spinel Mn1.8Fe1.2O4. Mn-Fe PBA were used as precursor to obtain Mn-Fe ternary oxides with controllable crystal structure and crystallinity for oxygen evolution. [Display omitted] •Mn–Fe ternary oxide nanocubes were obtained via thermal decomposition of Mn–Fe Prussian blue analogue precursor.•Catalysts with different crystal structure and crystallinity could be obtained through modulating of calcination conditions.•Mn–Fe Prussian blue analogue precursor could be transformed to bimetallic oxides with cubic bixbyite structure.•Bixbyite Mn1.2Fe0.8O3 samples showed superior oxygen evolution reaction activity than spinel Mn1.8Fe1.2O4 structure samples.•Bimetallic Mn1.2Fe0.8O3 catalyst with low crystallinity shows the best electrocatalytic activity towards water oxidation.