Premium
Promotive Effect of Bicarbonate Ion on Two‐Electron Water Oxidation to Form H 2 O 2 Catalyzed by Aluminum Porphyrins
Author(s) -
Kuttassery Fazalurahman,
Sebastian Abin,
Mathew Siby,
Tachibana Hiroshi,
Inoue Haruo
Publication year - 2019
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201900560
Subject(s) - catalysis , bicarbonate , inorganic chemistry , ion , chemistry , aluminium , photochemistry , organic chemistry
Two‐electron water oxidation initiated by one‐electron oxidation of aluminum porphyrins (AlTMPyP) is an alternative water oxidation to the conventional four‐electron pathway and could help to avoid the bottleneck subject of photon‐flux density in artificial photosynthesis. Here, a dramatic enhancement of the reactivity by bicarbonate ion in the two‐electron water oxidation to form H 2 O 2 is reported. An addition of sodium carbonate (Na 2 CO 3 ) controlled both catalytic current and product selectivity of the two‐electron water oxidation to enhance the activity of AlTMPyP at pH≈10–11. Controlled potential electrolysis experiments at different concentrations of Na 2 CO 3 (10–100 m m ) showed that peroxide selectivity was improved up to approximately 73 % by the increase of [Na 2 CO 3 ] added to the system. The promotion of the reaction cycle was induced by an enhanced dynamic capturing of H 2 O 2 from the hydroperoxy complex of AlTMPyP through an attack of a bicarbonate ion. The detailed electrochemical studies and product selectivity indicated that the bicarbonate ion served as a good cofactor for producing H 2 O 2 from water. At stronger alkaline conditions (pH 12.5), however, a retardative effect of the addition of Na 2 CO 3 on the catalytic reactivity was observed.