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Preparation of Polyoxometalate-based Photo-responsive Membranes for the Photo-activation of Manganese Oxide Catalysts
Published on: August 7, 2018
Water oxidation by lambda-MnO2: catalysis by the cubical Mn4O4 subcluster obtained by delithiation of spinel LiMn2O4
David M Robinson1, Yong Bok Go, Martha Greenblatt
1Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA.
Abstract:
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).
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