δ-MnO2-Mn3O4 Nanocomposite for Photochemical Water Oxidation: Active Structure Stabilized in the Interface
δ-MnO2-Mn3O4 Nanocomposite for Photochemical Water Oxidation: Active Structure Stabilized in the Interface
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DOI：
10.1021/acsami.6b09984
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发表时间：
2016-10-19
影响因子：
9.5
通讯作者：
Feng, Shouhua
中科院分区：
文献类型：
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作者：
Geng, Zhibin;Wang, Yanxiang;Feng, Shouhua
纯相锰氧化物作为水氧化催化剂已被广泛研究，但进一步提高其活性具有很大的挑战性。在此，我们报告了一种通过制备具有活性界面的 Mn3O4 和 δ-MnO2 纳米复合材料来提高水氧化活性的有效方法。该纳米复合材料是通过部分还原方法实现的，该方法诱导 Mn3O4 纳米颗粒从 δ-MnO2 纳米片表面原位生长。通过X射线光电子能谱(XPS)和X射线吸收光谱(XAS)证实，最佳成分为38%Mn3O4和62%δ-MnO2。 (δ-MnO2-Mn3O4纳米复合材料是一种高活性的水氧化催化剂，其转换频率(TOP)为0.93 s(-1)，远高于δ-MnO2和Mn3O4的彩虹组分。我们认为，水氧化活性的增强可以通过两种组分之间的活性界面来解释。在相界面处，黑锰矿相向相转变过程中，由于晶格无序，引入了弱Mn-O键。水钠锰矿相，为水氧化催化提供活性位点。我们的研究阐明了提高锰氧化物水氧化活性的新观点。
Pure phase manganese oxides have been widely studied as water oxidation catalysts, but further improvement of their activities is much challenging. Herein, we report an effective method to improve the water oxidation activity by fabricating a nanocomposite of Mn3O4 and delta-MnO2 with an active interface. The nanocomposite was achieved by a partial reduction approach which induced an in situ growth of Mn3O4 nanoparticles from the surface of delta-MnO2 nanosheets. The optimum composition was determined to be 38% Mn3O4 and 62% delta-MnO2 as confirmed by X-ray photoelectron spectra (XPS) and X-ray absorption spectra (XAS). The (delta-MnO2-Mn3O4 nanocomposite is a highly active water oxidation catalyst with a turnover frequency (TOP) of 0.93 s(-1), which is much higher than the iridividUal components Of delta-MnO2 and Mn3O4. We consider that the enhanced water oxidation activity could be explained by the active interface between two components. At the phase interface, weak Mn-O bonds are introduced by lattice disorder in the transition of hausmannite phase to birnessite phase, which provides active sites for water oxidation CatalysisiOur study illustrates a new view to improve water oxidation activity of manganese oxides.