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Oxygen Evolution Catalysts Based on Ir–Ti Mixed Oxides with Templated Mesopore Structure: Impact of Ir on Activity and Conductivity
Author(s) -
Bernsmeier Denis,
Bernicke Michael,
Schmack Roman,
Sachse René,
Paul Benjamin,
Bergmann Arno,
Strasser Peter,
Ortel Erik,
Kraehnert Ralph
Publication year - 2018
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.201800932
Subject(s) - catalysis , oxygen evolution , oxide , materials science , mesoporous material , chemical engineering , water splitting , crystallinity , electrolysis of water , inorganic chemistry , iridium , electrolysis , electrochemistry , nanotechnology , photocatalysis , chemistry , organic chemistry , electrode , composite material , electrolyte , engineering , metallurgy
The efficient generation of hydrogen via water electrolysis requires highly active oxygen evolution catalysts. Among the active metals, iridium oxide provides the best compromise in terms of activity and stability. The limited availability and usage in other applications demands an efficient utilization of this precious metal. Forming mixed oxides with titania promises improved Ir utilization, but often at the cost of a low catalyst surface area. Moreover, the role of Ir in establishing a sufficiently conductive mixed oxide has not been elucidated so far. We report a new approach for the synthesis of Ir/TiO x mixed‐oxide catalysts with defined template‐controlled mesoporous structure, low crystallinity, and superior oxygen evolution reaction (OER) activity. The highly accessible pore system provides excellent Ir dispersion and avoids transport limitations. A controlled variation of the oxides Ir content reveals the importance of the catalysts electrical conductivity: at least 0.1 S m −1 are required to avoid limitations owing to slow electron transport. For sufficiently conductive oxides a clear linear correlation between Ir surface sites and OER currents can be established, where all accessible Ir sites equally contribute to the reaction. The optimized catalysts outperform Ir/TiO x materials reported in literature by about a factor of at least four.