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Colloidal Fe III , Mn III , Co III , and Cu II Hydroxides Stabilized by Starch as Catalysts of Water Oxidation Reaction with One Electron Oxidant Ru(bpy) 3 3+
Author(s) -
Chikunov Andrei S.,
Taran Oxana P.,
Pyshnaya Inna A.,
Parmon Valentin N.
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201800957
Subject(s) - catalysis , chemistry , oxidizing agent , hydroxide , inorganic chemistry , colloid , redox , organic chemistry
Abstract Colloidal catalysts for oxidation of water to dioxygen, which are stable on storage and under the reaction conditions, are synthesized based on Co III , Mn III , Fe III and Cu II hydroxides. Stabilization of the colloids with dextrated starch allows the process of hydroxide ageing to be stopped at the stage of the formation of primary nuclei (ca. 2–3 nm from transmission electron microscopy data). Molecular mechanics and dynamic light scattering studies indicate a core‐shell type structure of the catalysts, where the hydroxide core is stabilized by the molecular starch network (ca. 5–7 nm). The colloidal catalysts are highly efficient in oxidizing water with one electron oxidant Ru(bpy) 3 3+ at pH 7 to 10. The influence of pH, catalyst concentration, and buffer nature on the oxygen yield is studied. The maximal yields are 72, 53, and 78 % over Fe‐, Mn‐ and Co‐containing catalysts, respectively, and turnover numbers are 7.8; 54 and 360, respectively. The Cu‐containing catalyst is poorly effective to the water oxidation (the maximal yield is 28 % O 2 ). The synthesized catalysts are of interest for stopped‐flow kinetic studies of the mechanism of the water oxidation and as precursors for anchoring nanosized hydroxides onto various supports in order to develop biomimetic systems for artificial photosynthesis.