用氧化物的晶体多态体对水进行光化学氧化:对催化物的结构要求
David M Robinson1, Yong Bok Go, Michelle Mui
1Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States.
Journal of the American Chemical Society
|February 9, 2013
概括
具有特定立方晶体结构的氧化物,特别是含有Mn(III的氧化物,显示出对水的氧化有催化作用. 其他结构,包括大多数MnO2多态,都不表现出任何活动,这突显了原子排列的重要性.
科学领域:
- 材料科学 材料科学 材料科学
- 催化剂是一种催化剂.
- 无机化学 无机化学 有机化学
背景情况:
- 氧化存在于许多晶体结构中,为研究结构-活性关系提供了一个独特的平台.
- 水的氧化是人工光合作用和能量转化中的关键过程.
研究的目的:
- 系统地研究氧化物原子位置和晶体结构对其对氧化水的催化效率的影响.
- 为了比较八个合成氧化结构的活性,专注于MnO2多态.
主要方法:
- 合成纯氧化多态的合成.
- 使用粉末X射线衍射,传输电子显微镜 (TEM) 和扫描电子显微镜 (SEM) 的表征.
- 通过氧化演变通过染料光氧化系统测量水的氧化率,并通过X射线光电子光谱 (XPS) 和能量分散式X射线光谱 (EDX) 分析催化剂表面.
主要成果:
- 对水氧化的催化活性仅在扭曲的立方相中观察到:Mn2O3 (bixbyite),Mn3O4 (hausmannite) 和λ-MnO2 (spinel).
- 这些活性相含有具有较长Mn-O键的Mn (III) 并且表现出Jahn-Teller扭曲.
- 大多数MnO2多态和LiMn2O4没有催化活性,与之前的一些报告形成鲜明对比.
结论:
- 氧化物在水氧化中的催化效率高度依赖于它们的特定晶体结构和Mn (III) 离子的存在.
- 雅恩-泰勒扭曲立方相对于水氧化催化非常重要,可能是由于结构灵活性提高.
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