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One Electron‐Initiated Two‐Electron Oxidation of Water by Aluminum Porphyrins with Earth's Most Abundant Metal
Author(s) -
Kuttassery Fazalurahman,
Mathew Siby,
Sagawa Shogo,
Remello Sebastian Nybin,
Thomas Arun,
Yamamoto Daisuke,
Onuki Satomi,
Nabetani Yu,
Tachibana Hiroshi,
Inoue Haruo
Publication year - 2017
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.201700322
Subject(s) - chemistry , electron transfer , catalysis , inorganic chemistry , hydrogen peroxide , photochemistry , hydroxide , porphyrin , metal , peroxide , organic chemistry
Abstract We report herein a new molecular catalyst for efficient water splitting, aluminum porphyrins (tetra‐methylpyridiniumylporphyrinatealuminum: AlTMPyP), containing earth's most abundant metal as the central ion. One‐electron oxidation of the aluminum porphyrin initiates the two‐electron oxidation of water to form hydrogen peroxide as the primary reaction product with the lowest known overpotential (97 mV). The aluminum‐peroxo complex was detected by a cold‐spray ionization mass‐spectrometry in high‐resolution MS (HRMS) mode and the structure of the intermediate species was further confirmed using laser Raman spectroscopy, indicating the hydroperoxy complex of AlTMPyP to be the key intermediate in the reaction. The two‐electron oxidation of water to form hydrogen peroxide was essentially quantitative, with a Faradaic efficiency of 99 %. The catalytic reaction was found to be highly efficient, with a turnover frequency up to ∼2×10 4 s −1 . A reaction mechanism is proposed involving oxygen–oxygen bond formation by the attack of a hydroxide ion on the oxyl‐radical‐like axial ligand oxygen atom in the one‐electron‐oxidized form of AlTMPyP(O − ) 2 , followed by a second electron transfer to the electrode.