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Optimization of Active Sites via Crystal Phase, Composition, and Morphology for Efficient Low‐Iridium Oxygen Evolution Catalysts
Author(s) -
Chen Hui,
Shi Lei,
Liang Xiao,
Wang Lina,
Asefa Tewodros,
Zou Xiaoxin
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202006756
Subject(s) - iridium , catalysis , morphology (biology) , oxygen evolution , phase (matter) , active oxygen , composition (language) , oxygen , chemical engineering , materials science , chemistry , biology , organic chemistry , zoology , engineering , art , electrode , electrochemistry , literature
Reducing the amount of iridium in oxygen evolution electrocatalysts without compromising their catalytic performances is one of the major requirements in proton‐exchange‐membrane water electrolyzers. Herein, with the help of theoretical studies, we show that anatase‐type TiO 2 ‐IrO 2 solid solutions possess more active iridium catalytic sites for the oxygen evolution reaction (OER) than IrO 2 , the benchmark OER catalyst. Note that the same is not observed for their rutile‐type counterparts. However, owing to their thermodynamic metastability, anatase‐type TiO 2 ‐IrO 2 solid solutions are generally hard to synthesize. Our theoretical studies demonstrate that such catalytically active anatase‐type solid‐solution phases can be created in situ on the surfaces of readily available SrTiO 3 ‐SrIrO 3 solid solutions during electrocatalysis in acidic solution as the solution can etch away Sr atoms. We experimentally show this with porous SrTiO 3 ‐SrIrO 3 solid‐solution nanotubes synthesized by a facile synthetic route that contain 56 % less iridium than IrO 2 yet show an order of magnitude higher apparent catalytic activity for OER in acidic solution.