Mesoporous oxides as efficient catalysts for the electrocatalytic oxygen evolution reaction (OER)

Hydrogen is considered an important energy carrier and feedstock for industrial applications. The generation of hydrogen can be realised by electrocatalytic water splitting. However, the efficiency of water electrolysers is limited by the slow kinetics of oxygen evolution reaction (OER). An increase in mass based OER activity is mandatory for a lower capital cost of electrolyser cells. In this thesis, synthesis routes are presented for new mesoporous metal oxide films used as catalytic layers for OER in alkaline or acidic media. The catalytic layers contain different metal oxides, such as NiO, IrO2 and IrO2/TiO2. The synthesis of metal oxide coatings with high accessible ordered mesopore structure was achieved via evaporation induced self assembly. The synthesis succeeds by utilizing PEO-b-PB-b-PEO triblock copolymers as a pore template, a suitable metal oxide precursor, and a final heat treatment under air. The synthesis conditions and corresponding physicochemical characterisations are shown in the discussion. Correlation of structure and OER activity was used to deduce structure-activity relationships. These relationships were then used to identify the most significant OER-controlling parameters. All identified OER-controlling parameters were combined in order to develop an OER-model describing which structural properties benefit OER activity the most. Furthermore, the influence on kinetic parameters such as Tafel slope was investigated. High OER-activities and low Tafel slopes were found for materials with low crystallinity, high surface area, high conductivity and electrocatalytic measurements conducted at moderate overpotentials (ca. η < 0,35 V). In order to demonstrate the commercial relevance of the catalytic layers synthesised in this work, their OER activity was compared with commercial reference catalysts. It was shown that oxide layers of this work exhibit a 11 to 24 times higher iridium mass based OER activity compared to commercial reference catalysts.

Author dc:creator

• Bernicke, Michael

Advisor dc:contributor.advisor

• Krähnert, Ralph

Licence dc:rights.uri

• https://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

en

Identifier URI

http://dx.doi.org/10.14279/depositonce-5500

OAI identifier oai:identifier

oai:depositonce.tu-berlin.de:11303/5907