Water Oxidation by λ-MnO2: Catalysis by the Cubical Mn4O4 Subcluster Obtained by Delithiation of Spinel LiMn2O4
Water Oxidation by λ-MnO2: Catalysis by the Cubical Mn4O4 Subcluster Obtained by Delithiation of Spinel LiMn2O4
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DOI：
10.1021/ja1055615
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发表时间：
2010-08-25
影响因子：
15
通讯作者：
Dismukes, G. Charles
中科院分区：
文献类型：
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作者：
Robinson, David M.;Go, Yong Bok;Dismukes, G. Charles
制备了纳米尖晶石LiMn_2O_4，用稀硝酸溶液处理LiMn_2O_4，在保持尖晶石结构的同时，使其骨架脱锂，以MnO_2为中心的LiMn_2O_4对水的氧化没有催化作用。在pH5.8条件下，用[Ru ~（2+）（2，2 '-bpy）（3）]/过硫酸盐体系研究了Mn ~（4+）的光化学反应.由柠檬酸盐路线合成的纳米晶LiMn_2 O_4得到的纳米尺寸的LiMn_2O_2显示出比通过微米和不规则颗粒尺寸的固相反应得到的纳米尺寸的LiMn_2O_4（转换频率：5 × 10（-6）mol O_2/s/mol Mn）显著更高的水氧化催化活性（转换频率：3 × 10（-5）mol O_2/s/mol Mn）。
Nanocrystalline spinel LiMn2O4 has been prepared and treatment of LiMn2O4 with dilute nitric acid solution resulted in the delithiation of the framework, while maintaining the spinel structure, lambda-MnO2 center dot LiMn2O4 is not a catalyst for water oxidation. Upon removal of the lithium, the cubical Mn4O4 cores become active sites for oxidizing water to molecular oxygen, which was investigated with the photochemical [Ru2+(2,2'-bpy)(3)]/persulfate system at pH 5.8. The nanosize lambda-MnO2 obtained from the nanocrystalline LiMn2O4, which was synthesized by the citrate route, shows a significantly higher water oxidation catalytic activity (Turnover Frequency: 3 x 10(-5) MOl O-2/s/mol Mn) than that obtained via solid state reaction with micrometer and irregular particle sizes (Turnover Frequency: 5 x 10(-6) mol O-2/s/mol Mn).