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Composition‐Dependent Effect of the Calcination of Cobalt‐, Nickel‐, and Gallium‐Based Layered Double Hydroxides to Mixed Metal Oxides in the Oxygen Evolution Reaction
Author(s) -
Chakrapani Kalapu,
Özcan Fatih,
Ortega Klaus Friedel,
Machowski Thomas,
Behrens Malte
Publication year - 2018
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201700936
Subject(s) - calcination , overpotential , cobalt , nickel , layered double hydroxides , inorganic chemistry , catalysis , oxygen evolution , coprecipitation , transition metal , chemistry , metal , materials science , hydroxide , electrochemistry , organic chemistry , electrode
Mixed cobalt and nickel based layered double hydroxides (LDHs) with Ga as the third cation and the mixed metal oxides (MMOs) resulting from their thermal decomposition were synthesized in various compositions through constant pH co‐precipitation and calcination. The structural and textural properties of the catalysts with variable Co/Ni ratios were assessed by N 2 physisorption, powder X‐ray diffraction, and electron microscopy. The obtained materials exhibit electrocatalytic activity for the oxygen evolution reaction in alkaline solution. The highest activity was found for catalysts containing both transition‐metal cations, Co and Ni. However, comparison of the LDH precursors and the calcined MMOs revealed a composition‐dependent effect of calcination. Co‐rich LDH tends to lose activity when calcined, whereas Ni‐rich LDH gains activity. The optimal cation composition of the LDH was Co 1.5 Ni 0.5 Ga with an overpotential of 382 mV. The highest performance among the MMOs, on the other hand, has been encountered for the Co 0.5 Ni 1.5 Ga composition, reaching a similar overpotential.