Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA.
J Am Chem Soc. 2010 Aug 25;132(33):11467-9. doi: 10.1021/ja1055615.
Nanocrystalline spinel LiMn(2)O(4) has been prepared and treatment of LiMn(2)O(4) with dilute nitric acid solution resulted in the delithiation of the framework, while maintaining the spinel structure, lambda-MnO(2). LiMn(2)O(4) is not a catalyst for water oxidation. Upon removal of the lithium, the cubical Mn(4)O(4) cores become active sites for oxidizing water to molecular oxygen, which was investigated with the photochemical [Ru(2+)(2,2'-bpy)(3)]/persulfate system at pH 5.8. The nanosize lambda-MnO(2) obtained from the nanocrystalline LiMn(2)O(4), 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).
纳米晶尖晶石 LiMn(2)O(4)已被制备，并用稀硝酸溶液处理 LiMn(2)O(4)导致框架脱锂，同时保持尖晶石结构 λ-MnO(2)。LiMn(2)O(4)不是水氧化的催化剂。除去锂后，立方 Mn(4)O(4)核成为将水氧化为氧气的活性位点，这是在 pH 5.8 下用光化学 [Ru(2+)(2,2'-bpy)(3)]/过硫酸盐体系进行研究的。通过柠檬酸途径合成的纳米晶 LiMn(2)O(4) 得到的纳米 λ-MnO(2)，其水氧化催化活性（ turnover frequency：3 x 10(-5) mol O(2)/s/mol Mn）显著高于通过固态反应获得的微米级和不规则颗粒尺寸的 λ-MnO(2)（ turnover frequency：5 x 10(-6) mol O(2)/s/mol Mn）。
